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PUBLIC HEALTH ASSESSMENT

ICG ISELIN RAILROAD YARD
JACKSON, MADISON COUNTY, TENNESSEE

ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

In order to determine what environmental contaminants may be a concern, ATSDR has evaluated all of the available environmental monitoring data. Environmental data was taken from references 1-5. Screening values were used as a basis for evaluation of the data and to determine which contaminants should be looked at more closely. Environmental screening values are health-based estimates of concentrations in environmental media below which no known or anticipated adverse effect on the health of persons should occur. The values allow an adequate margin of safety. Appendix B and the Public Health Implications section of this document contain a list and descriptions of the screening values used in this public health assessment.

A contaminant is selected for further evaluation if the contaminant in a valid environmental sample exceeds environmental screening values. The presence of a contaminant on the list in the Appendix B Tables does not mean that either exposure to the contaminant or adverse health effects has occurred or will occur. Inclusion in the lists indicates only that the potential for human exposures to the selected contaminants and the potential for adverse human health effects as a result of any exposures to the selected contaminants will be discussed in more detail in later sections of this public health assessment.

Appendix B, Tables 1-13 list the contaminants detected above health comparison values in the various waste materials and environmental media (soil, groundwater, surface water, and sediments) found on and off the ICG Iselin Railroad Yard NPL site. In addition, these tables list contaminants for which ATSDR does not have comparison values. Those contaminants which are known carcinogens whose maximum concentration exceeded its cancer risk evaluation guide (CREG) and those contaminants which are known carcinogens but do not have a CREG are also included in the tables of Appendix B. In addition to comparing the detected concentrations of organics and inorganics found in surface soils (0-3 inches below the surface), sub-surface soils (greater than three inches below the surface) and sediment to health-based comparison values, it is also prudent to compare the detected levels to background or normal soil/sediment levels. This type of comparison helps identify which of the contaminants detected are above background levels and may be site-related.

A. On-Site Contamination

The environmental investigations conducted by the Tennessee Department of Environment and Conservation (TDEC) and RMT, Inc. have identified various contaminants in waste materials and other on-site media. This part of the ICG Iselin Railroad Yard public health assessment will identify what contaminants were detected above health comparison values in the waste materials and environmental media (i.e. groundwater, soil, surface water, etc.). Missing and inconsistent data will be discussed in the data gaps subsection.

1. Groundwater (Monitoring Wells, Appendix B, Table 1)

During the Phase I Remedial Investigation (RI) two rounds of sampling [RI(1) and RI(2)] were conducted to collect groundwater samples from 10 monitoring wells. Though both filtered and unfiltered samples were collected for metal analysis, only unfiltered sample data were used to assess groundwater quality. The filtered samples were used for comparison only. Benzene (0.002J milligrams per liter (mg/l)), arsenic (0.0249 mg/l), and cyanide (0.401 mg/l), were detected at concentration levels in excess of ATSDR's environmental screening values. Dibenzofuran, 1,1-dichloroethane (DCA), 2-methylnaphthalene, carbazole, iron, and sodium were also detected. ATSDR does not have screening values for these chemicals. The overall frequency of detection of organic contaminants was low and most compounds were detected in the same monitoring well (MW02). Monitoring well 02 is a shallow well (approximately 17 feet deep), located near the metal building with its screen placed near the water table surface.

Monitoring well 07 (MW07) is located east of the maintenance building. This well was found to be contaminated with benzene (0.001 mg/l), arsenic (0.024 mg/l) and manganese (2.25 mg/l). These concentrations equaled or exceeded ATSDR's environmental screening values. Arsenic and manganese are naturally occurring in the soils associated with the Site. The suspected carcinogen 1,4-dichlorobenzene was also detected in the monitoring well.

During the SRI (November and December 1994) groundwater samples were collected from temporary wells (TW) to characterize groundwater quality, using direct push or similar technology. The direct push technology advances a water sampling device through the soil to a selected depth below the water table without drilling a borehole or generating drill cuttings. The samples were analyzed for VOCs included on the target compound list (TCL). Trichloroethene (TCE) was detected above ATSDR's screening values for carcinogenic effects in a well located in the area of the former blow house. TW5 was developed in 1995, approximately 190 feet south southeast of the southeast corner of the locomotive maintenance building, using a submersible pump and a surge block. Analysis of samples found the water to be contaminated with bromodichloromethane and dibromochloromethane at concentrations above ATSDR's environmental screening values for carcinogenic effects. DCA and 2-propanol was also detected, however, ATSDR does not have screening values for these contaminants.

After evaluating the data collected from the temporary well samples, it was decided that additional samples needed to be taken in order to better characterize on-site groundwater quality. Groundwater samples were taken from wells in 13 locations. These samples were taken at three different depths (4-9, 30, and 40 feet below the surface). Some of the samples taken at depths of 30 feet or greater were found to be contaminated with 1,1-dichloroethene (DCE); TCE; and vinyl chloride at concentrations above ATSDR's screening values. Some of the highest concentrations of VOCs were found on the east side of the site, down-gradient of the municipal landfill which is located near the Site.

2. Soils

For the purposes of this public health assessment, ATSDR defines surface soil as the top 0" - 3" of soil. Samples taken at a depth greater than three inches but less than or equal to six inches is considered unspecific soil. Samples taken at a depth greater than six inches is considered subsurface soils.

Unspecific Soils (Appendix B, Table 2)

During the RI (June 1992), soil samples were collected on-site from a depth of 0"-6" below the surface in 17 areas of potential sources to see if releases had occurred. In the area of the Norfolk-Southern Rail Tie Pile/Dump (SS17A), carcinogenic polycyclic aromatic hydrocarbons (PAHs) were found at a maximum concentration of 6.45 milligrams PAH per kilogram soil (6.45 mg/kg). This value exceeded ATSDR's environmental screening value for benzo(a)pyrene. Carbazole (0.34 mg/kg estimated) was also found in area of the rail tie pile. ATSDR has not developed an environmental screening value for carbazole. In the tank car loading/unloading area dibenzofuran, 2-hexanone, naphthalene, and 2-methylnaphthalene were detected. ATSDR does not have screening values for these chemicals in soil. Dieldrin was found in the battery storage area at concentrations exceeding ATSDR's environmental screening value for possible carcinogenic effects. Several metals including antimony, arsenic, and chromium were found at concentrations above ATSDR screening values at other site locations.

In December 1995, soil samples were collected from the area of the former septic tank and southeast of the locomotive maintenance building. 2-Methylnaphthalene was found in the soils in the are of the former septic tank. ATSDR does not have screening values for 2-methylnaphthalene in soil.

During the SRI, a composite sample was taken in the fenced area between the locomotive maintenance building and the former power plant. The sample was analyzed for polychlorinated biphenyls (PCBs). The PCBs were not detected above the method detection limit. The method detection limit was below ATSDR's environmental screening values for PCBs in soil.

Sub-surface Soil (Appendix B, Table 3)

Subsurface soil boring (>6") samples were collected in June 1992, December 1994, and December 1995. The resulting concentration from most of the analyses was below the quantitation limit. Carcinogenic PAHs and arsenic were detected in samples at concentrations exceeding ATSDR's environmental screening values. Lead, other metals, pesticide compounds, and VOCs for which ATSDR does not have environmental screening values were also detected. Most were collected in the area of the fueling shed and rail tie pile.

Surface Soil (Appendix B, Table 4)

During the SRI 13 surface soil samples (0"-3") were collected from four different areas on the site [rail tie pile (4 samples), old battery storage area (3 samples), vicinity of the former roundhouse area (3 samples) and northeast of the locomotive maintenance building (3 samples)]. The samples taken in the area of the rail tie pile were composited to make one sample to evaluate the lateral extent of metals detected in a sample collected during the RI. Several metals were detected in the composited sample. The concentrations of most of the metals did not exceed the background level for each of the contaminants in the soil of the eastern United States (12). Arsenic exceeded ATSDR's screening values for noncarcinogenic and carcinogenic effects in soil. The concentration of chromium did not exceed ATSDR's screening value for noncarcinogenic effects, however, chromium in the hexavalent state is carcinogenic via inhalation. Since the valence level of the chromium was not given it was assumed to be hexavalent. Samples taken northeast of the locomotive maintenance building contained lead ranging in concentrations from 8.1-2020 mg/kg. ATSDR does not have an environmental screening value for lead in soil. Samples collected in the former roundhouse area were found to be contaminated with the insecticide dieldrin, above ATSDR's environmental screening values. Other pesticide compounds were also found including carbazole, and 2-methylnaphthalene. ATSDR does not have environmental screening values for these contaminants. The concentrations of carcinogenic PAHs were converted to their relative potency as compared to benzo(a)pyrene and the calculated concentrations were then compared to the screening values for benzo(a)pyrene. The estimated values for carcinogenic PAHs exceeded ATSDR's screening values for benzo(a)pyrene.

3. Air (Appendix B, Table 5)

Air samples were collected on May 19, 1992 to determine the presence and concentration of airborne metals, VOCs, and PAHs. Various Occupational Safety and Health Administration and National Institute for Occupational Safety and Health methods were used to analyze the samples. Samples were taken upwind (on-site), near the metal building, and downwind (off-site). The wind direction was determined at the time the samples were collected. Although the level of methylene chloride detected on-site did not exceed ATSDR's environmental screening value for carcinogenic effects, the level upwind did exceed the screening value. Iron and phosphorous were also detected in the air samples. ATSDR does not have air screening values for these contaminants.

Air was sampled on December 14, 1994, to evaluate if airborne constituents were present at the site. The upwind samples were taken south of the main site, between two groups of railroad tracks. None of the contaminants were above ATSDR's environmental screening values. The on-site sample was collected in the middle of the main site, northwest of the tankcar loading/unloading area, southwest of MW-2. Arsenic, chromium, inorganic mercury, and nickel were detected above ATSDR's environmental screening values. The downwind sample was collected north of the site, on the terrace. Iron was detected in the sample, however, ATSDR does not have an environmental screening value for iron.

4. Surface Water (Appendix B, Table 6)

During the initial remedial investigation filtered and unfiltered surface water samples were collected in the area of the wastewater treatment lagoon and the drainage ways bordering the eastern part of the site. SW01 served as the on-site background indicator. The concentration of manganese within that sample and other samples exceeded ATSDR's screening value. Sampling point SW04 is located in the intermittent tributary near a discharge point into Jones Creek. The sample was contaminated with 2-hexanone and 4-methyl-2-pentanone. ATSDR does not have screening values for these contaminants. Chromium and lead were detected in waters from the wastewater lagoon at concentrations above ATSDR's screening values for drinking water. These values are used as an initial screen. ATSDR is aware that the surface water impoundments on site do not serve as a potable water source.

5. Sediment (Appendix B, Table 7)

In June 1992, sediment samples were collected in the wastewater treatment lagoon and the drainage ways bordering the eastern part of the site using the Wildco sediment sampler or stainless steel scoops. Grab samples for VOCs were collected first, followed by other sampling fractions. Pebbles larger than five millimeters in diameter were removed from the sampler prior to placing the sample in the sample container. Dieldrin (0.06 mg/kg), arsenic (39.8 mg/kg), antimony (29.7 mg/kg), and manganese (9290 mg/kg) collected from the drainage way near the southeast corner of the locomotive maintenance building downstream of the lye vat (where the old floor drain system is believed to have been located) exceeded ATSDR's environmental screening values. Cadmium, while not exceeding ATSDR's screening values, was also detected in the sample and is a carcinogen. Analytical results of sediment samples from Jones Creek and its confluence with the unnamed tributary near the southern portion of the site indicate that in the area immediately downstream of the former discharge point for the wastewater lagoon, high concentrations of chromium (1950 mg/kg) are present. DCA was found in the wastewater lagoon sediments.

Samples taken from a ditch that flows in a southeast direction from the east side of the locomotive maintenance building, was shown to be contaminated with elevated levels of carcinogenic PAHs, pesticides, and heavy metals. Lead was detected in the wastewater lagoon sediments.

6. Waste Material (Appendix B, Table 8)

A sample of waste sludge containing many organic and inorganic constituents was collected from the neutralization tank during the Phase I remedial investigation. Several VOCs, semi-VOCs, and metals exceeded ATSDR's environmental screening values. According to the Toxicity Characteristic Leaching Procedure (TCLP) analysis, the waste is characteristically nonhazardous.

7. Data Gaps

Many organic compounds were detected in surface soils and then later invalidated following EPA's validation protocol. Two single day air sampling events occurred. Based upon data reviewed to date there may be some concern about inhalation exposures occurring in the vicinity of the wastewater treatment facility and rail tie pile/dump. No air and soil gas sampling occurred at these locations. In order for ATSDR to make a more accurate evaluation of the possible extent of air contamination, more sampling events under varying environmental conditions would have been needed.

B. Off-Site Contamination

The environmental investigations conducted by TDEC and RMT, Inc. have identified various contaminants in off-site groundwater, surface water, sediments and soils. This part of the public health assessment will identify what contaminants were detected above environmental screening values in the various environmental media. Missing and inconsistent data will be discussed in the data gaps subsection.

1. Groundwater

Monitoring Wells (Appendix B, Table 9)

Monitoring wells were installed off-site to provide data regarding groundwater flow and quality. MW01 and MW01A were established upgradient of site related groundwater flow to provide data on background water quality. These wells which are located on the Washington-Douglas Elementary School property were found to be contaminated with several heavy metals. However, the contaminants appear to be related to the landfill that is located near the site. Contaminants (VOCs) from the landfill have been determined to be migrating onto the ICG Iselin Railroad Yard site.

Municipal Wells (Appendix B, Table 10)

The Jackson Utility District wells JUD06, JUD07, and JUD08 (south well field) were sampled as part of the Phase I RI. Benzene was detected in JUD07 at 0.001 mg/l. This estimated concentration is equal to the ATSDR screening value. Tetrachloroethene (PCE) was detected in JUD06 twice at 0.003 mg/l, and 0.004 mg/l. Trichloroethene (TCE) was detected once in JUD06 at an estimated concentration of 0.003 mg/l and in both sampling events in well JUD08 at an estimated concentration of 0.005 mg/l and 0.004 mg/l respectively. Both PCE and TCE are heavier than water and tend to sink. Although these concentrations exceed ATSDR's environmental screening values, ATSDR requires more data and information to determine whether or not the contamination is related to the ICG Iselin Railroad Yard NPL site. Based upon site sampling data reviewed by ATSDR to date, PCE is not likely a site-related contaminant. JUD06 was not in use at the time that the sampling occurred. The well now yields about 87,000 gallons of water per hour. In addition, according to JUD officials, JUD07 is not used because it has a damaged well screen and JUD08 is not used because of high levels of manganese and iron (2).

2. Surface Water (Appendix B, Table 11)

Surface water samples were collected from Jones Creek upstream (SW5) of the site, from Jones Creek downstream of a former municipal landfill (SW6), and on-site (SW1) during the initial RI. These samples served as background indicators. Arsenic was found in the samples at concentrations less than the instrument detection limit, however, the instrument detection limit exceeds ATSDR's environmental screening value for carcinogenic effects. Manganese was found in SW05 at a maximum concentration of 0.366 mg/l.

During the SRI surface water samples (filtered and unfiltered) were collected from two locations in Jones Creek downstream of its confluence with the unnamed tributary from the southern portion of the site. The samples were analyzed for acetone, carbon disulfide, diethylphthalate, and inorganic parameters on the TAL. Only manganese (0.389 mg/l) was detected at concentrations above ATSDR's environmental screening values.

3. Sediment (Appendix B, Table 12)

Sediment samples were collected during the RI from Jones Creek upstream (SD5) of the site, from Jones Creek downstream of the former municipal landfill (SD6), and on-site (SD1). The off-site background samples were contaminated with high concentrations of heavy metals including: aluminum, iron, and manganese. Copper and manganese concentrations were elevated in samples taken from Jones Creek downstream of the unnamed tributary that receives surface water run-off from the site.

4. Unspecific Soils (Appendix B, Table 13)

In June 1992, soil samples were taken from the terrace above the site in the vicinity of the Washington-Douglas Elementary School. The samples were shown to be contaminated with elevated levels of metals including: aluminum, arsenic, iron, and lead.

5. Data Gaps

Although a residential area and the Washington-Douglas Elementary School border the site to the north, surface soil samples (0"-3") were not collected from residential yards and the school property. Since the level of various heavy metals were elevated in the unspecific soil samples (0"-6") taken in the vicinity of the school, surface soil data (as defined by ATSDR) would be needed to determine if children attending the school are exposed to the contaminants at levels of public health concern. ATSDR can not make a determination regarding possible links between site contaminants and the contamination found in the municipal wells located near the site. More information and data are needed to determine the impact of the wells during operation on the flow of groundwater in the area.

C. Quality Assurance and Quality Control

In preparing this public health assessment, ATSDR relies on the information provided in the referenced documents. We assume that adequate quality assurance and quality control measures were followed regarding chain of custody, laboratory procedures, and data reporting. The analyses, conclusions, and recommendations in this health assessment are valid only if the referenced documents are complete and reliable.

D. Physical Hazards

ATSDR is not aware of any physical hazards other than those normally associated with railroad yard sites to be present at this site.

E. Review of Toxic Chemical Release Inventory (TRI) Data (10-11)

To identify other possible facilities that could contribute to the contamination at the ICG Iselin Railroad Yard NPL site or the discharges from such facilities that could increase an individual's exposure to site-related contaminants, ATSDR searched the 1987 to 1992 files of the TRI databases. TRI was developed by the EPA from chemical release information (air, water, and soil) provided by certain industries.

Several limitations of TRI data should be noted. The air release data in TRI may be estimates or actual measurements. Many of the reported data are estimates based on conservative (overestimated) scenarios. Consequently, the levels of emissions recorded in TRI are often biased on the high side. In addition, reporting is restricted to specific chemicals that are used or releases above specified amounts. Finally, it is believed that there have been and still are industries that do not report releases. Smaller industries may not be aware that reporting requirements exist or that they are responsible for such reports.

The search of the TRI revealed that various potentially toxic chemicals were released by industries in Jackson, TN. However, it cannot be determined from the TRI information whether these releases have contributed to contamination at the site or whether persons in the site area have been exposed to contaminants from these releases. Therefore, the results from the TRI search are not considered further in this public health assessment.

PATHWAYS ANALYSIS

In this section of the public health assessment, the possible environmental exposure pathways are evaluated to help determine whether individuals have been, are being, or will be exposed to site-related contaminants. The pathway analysis consists of five elements:

  1. Identifying contaminants of concern possibly related to the site;

  2. Determining that contaminants have been/are being/will be transported through an environmental medium;

  3. Identifying a point of exposure (i.e., a place or situation where people might be exposed to the contaminated media);

  4. Determining that there is a plausible route of human exposure (i.e., can the contaminant enter the body?); and

  5. Identifying an exposed population (i.e., how many people, if any are at the point of exposure?).

An environmental exposure pathway is considered complete when there is good evidence that all five elements exist (12). The presence of a completed pathway indicates that human exposure to contaminants has occurred in the past, is occurring, or will occur in the future. When one or more of the five elements of an exposure pathway are missing, that pathway is considered potential. The presence of a potential exposure pathway indicates that human exposure to contaminants could have occurred in the past, could be occurring, or could occur in the future. An exposure pathway can be eliminated from consideration if at least one of the five elements is missing and will never be present. Although it is considered a conservative approach, if there is uncertainty about the site-relatedness of the contaminants of concern in an exposure pathway, the pathway will be evaluated as if the contaminants were site-related.

A. Completed Environmental Exposure Pathways (Appendix C, Table 1)

There is evidence based on site history, site data, and interviews with former on-site workers and community members, that people at and near the ICG Iselin Railroad Yard NPL site were likely exposed on an intermittent basis to contaminated air (via inhalation), on-site surface soil (via incidental ingestion, dermal contact, and possibly via inhalation), surface water and sediments in the intermittent tributary and Jones Creek (via inhalation, incidental ingestion, and dermal contact), and off-site soils (via inhalation, incidental ingestion, and dermal contact).

1. On-site Surface Soil

Persons working in the area of the locomotive maintenance building and others (trespassers) may have been exposed to concentrations of lead in surface soil via incidental ingestion, direct contact, and/or inhalation. Assuming that the maximum concentration of the contaminants found in surface soil samples taken during the RI was in the top 0"-3" of soil, workers could have been exposed to those contaminants detected in soil samples. On-site workers and others were likely exposed to carcinogenic PAHs and carbazole in the former roundhouse area and in the area of the rail tie pile dump; pesticide compounds in the area of the former roundhouse; various metals in the area of the air brake maintenance building, the fueling shed, and the office storage building; dibenzofuran and VOCs in the tankcar loading/unloading area; and dieldrin in the battery storage area. Arsenic, above environmental screening values, was detected in the soils near the rail tie pile/dump.

Children have been reported to have played on the site. Soil ingestion is an important route of exposure for children who played on-site, particularly for children younger than 6 years (13). Neither the tie pile or the contaminated soils have been removed from the site. Therefore, current on-site workers and others may continue to be exposed to the contaminants in the pile/dump. Because of limited air sampling it is not known if inhalation exposure is occurring or will occur in the vicinity of the rail tie pile dump.

2. Air

Persons on-site and residents in the vicinity of the site were likely exposed to constituents in air. Various ambient air contaminants, most noticeably methylene chloride, arsenic, and chromium were detected during the two sampling events. Some of the contaminants may have been introduced into the breathing zone by activities which disturbed the soil. Other contaminants may have resulted from outside emissions not associated with the ICG Iselin Railroad Yard NPL site. Contaminants released to the ambient air are dispersed by the winds. Any contaminants emitting from the site and the surrounding area will mix and disperse throughout the area. Off-site sampling data indicated the presence of methylene chloride and phosphorous at higher concentrations upwind than on-site and downwind. Regardless of the sources, measurements of air flow through the site indicate that workers and others in the vicinity of the site have been and are being exposed via inhalation. Since the site continues to be used for various purposes and contaminated surface soils have not been removed, future exposure will likely occur.

3. On-Site and Off-Site Surface Water and Sediment

Based on reports from area residents, children played in on-site waterbodies. Based upon what is currently known about the site, these water bodies were mostly the on-site portions of the Intermittent Tributary (stream) and Jones Creek. In addition, the off-site portions of Jones Creek are used for recreational purposes.

Wastewater from site operations entered the settling basin via the drainage ways. From the basin it entered the wastewater treatment lagoon. Water from the wastewater treatment lagoon (which currently only receives water from surface water runoff into the lagoon and precipitation) was discharged to a drainage ditch and entered the intermittent tributary. The tributary flows southeast for approximately 150 feet into Jones Creek. Analyses of on-site and off-site surface water and sediment from the drainage ways, intermittent tributary and Jones Creek indicate that dieldrin, carcinogenic PAHs, arsenic, cadmium, iron, mercury, zinc, and copper (sediment only); 2-hexanone and 4-methyl-2-pentanone (surface water only); lead, chromium, and manganese were occasionally above screening values (or were present but ATSDR does not have a screening value for the contaminant in these media). Children and others in the past were exposed via dermal contact and inhalation while wading in the drainage ways and intermittent tributary. People were also exposed while engaging in recreational activities such as swimming and wading in Jones Creek.

4. Off-Site Soils on Terrace Above Site

Although the contamination has not been shown to be site-related, based upon data reviewed by ATSDR, the soils in the vicinity of the Washington-Douglas Elementary School are contaminated with various heavy metals. The soil samples were taken from the top six inches in order to get background estimates for comparison with contaminant levels at the site. Analysis of the samples revealed than contaminant concentrations in excess of ATSDR's screening levels exists for antimony, arsenic, barium, manganese, and vanadium. In addition, aluminum, iron, and lead were detected. Assuming that the maximum concentration of these contaminants is present in the top three inches of the soil then it is likely that people were exposed to the contaminants via incidental ingestion, inhalation, and dermal contact. These possible exposures are of importance because the school is now used to house a headstart program. Any children who play in the soil and exhibit pica behavior would be at greater risk of exposure. It should also be noted that arsenic, iron, and manganese are naturally-occurring elements found in most every soil type.

B. Possible Environmental Exposure Pathway (Appendix C, Table 2)

1. On-Site Groundwater

Analyses of groundwater samples from on-site monitoring wells indicate that the groundwater on the site is contaminated with various VOCs and metals. Most of the contaminants above ATSDR environmental screening values were found in wells located near the metals and locomotive maintenance buildings. It is possible that current and former site operations are not the sole source of this contamination. The groundwater from a well located east of the locomotive maintenance building was found to be contaminated with benzene, 1,4-dichlorobenzene, arsenic, and manganese. A monitoring well to the north of the site which was used to determine background concentrations of chemicals in groundwater was found to be contaminated with various metals at concentrations above ATSDR environmental screening values. On-site groundwater is not used as a potable water source. The direction of groundwater flow in the area of the site is reportedly south-southwest. If someone were to drill a well into the contaminated groundwater for a primary water source exposure would occur via ingestion, inhalation, and dermal contact. Due to the contaminated groundwater beneath the Site, TDEC would not allow a water supply well to be installed at the Site.

2. Sludge

Prior to the installation of the pollution abatement system in the 1970s, waste and wastewater from the lye vat used to degrease locomotive parts was drained into the on-site drainage ditch. On-site workers and others could have come into contact with the contaminated wastes in the drainage ditch.

3. On-Site Soils Greater than 3" Below Surface

Based upon data from the RI and SRI, subsurface soils are contaminated with VOCs, semi-VOCs, pesticide compounds, and metals. It is possible for on-site workers and others to be/have been exposed to the contaminants in this medium via inhalation of fugitive dusts, incidental ingestion, or dermal contact during excavation activities or any other activity which may have resulted in disturbing soil greater than three inches below the surface. If such exposures occurred, the areas of greater concern would have been the fueling shed, the rail tie pile/dump, and the area immediately surrounding the locomotive maintenance building.

4. Off-Site Groundwater

Groundwater monitoring data indicate that metals have been detected in the groundwater. The monitoring well in which the metals were found was used during the remedial investigation to indicate background groundwater quality. It is unlikely that the contamination is site-related. Area residents are currently supplied potable water by the JUD. Anyone using water from a well supplied by the contaminated aquifer (non-potable purposes) would be exposed to the contaminants via inhalation, incidental ingestion, and dermal contact.

5. Municipal Water

The JUD supplies drinking water to approximately 60,000 persons from 10 of its wells located within four miles of the site. The south well field which is located within ½ mile of the site may be producing up to 10 million gallons of water per day by the year 2005. Water in the wells are blended and no single well provides more than 40% of the system demand.

The wells receive their water from the alluvial/fluvial/lower combined Claiborne and Wilcox aquifer. Contaminants from the site have the potential enter this aquifer, and therefore be transported to the nearby wells. Analyses of samples from the closest well to the site being used to produce water, (JUD06), indicates that it has been contaminated with tetrachloroethene (PCE). The PCE does not appear to be site-related. Other potential sources of the contamination include the municipal landfill and nearby dry-cleaning facilities. It is possible that in the past, prior to discovery of contamination, people were exposed to the PCE. To determine the level of PCE that may have actually entered the home (if any), ATSDR would have needed data from the potable water source (tap water samples) to evaluate.

C. Non-Apparent Environmental Exposure Pathway (Appendix C, Table 3)

1. Sludge Pathway

During the ICG Iselin operations the lye vat was used to degrease larger locomotive parts. Prior to the installation of the pollution abatement system in the 1970s, waste was drained from the lye vat into the on-site drainage ditch whenever it became necessary to make a new batch of lye. With the installation of the pollution abatement system waste from the lye vat was drained into an unlined underground neutralization tank composed of 10 inch thick concrete walls. Based upon results of waste (sludge) samples taken from the neutralization tank during the initial remedial investigation, the tank is contaminated with various metals and volatile organic compounds. Since this is an underground tank it is highly unlikely that people would come into contact with the contaminated sludge.

2. On-site Groundwater

There are no wells for potable purposes known to be or have been receiving their supply from the contaminated groundwater. On-site groundwater is not used for human consumption. Exposure to this medium is unlikely.

3. Wastewater Lagoon Surface Water and Sediment

Samples taken from the on-site wastewater treatment facility (lagoon) indicate that chromium and lead are above health screening values. 1,1-Dichloroethane was also found. The lagoon currently only receives water from surface water runoff into the lagoon and precipitation. The lagoon is fenced. Although the fence is not always locked it is believed that direct exposure to the contaminants in these media is no longer occurring.

4. Municipal Water

Because water is blended prior to distribution and PCE is a VOC, the concentration of the contaminant would be reduced by at least 60%. Therefore, it is very unlikely that people using the water, presently and in the future, at its exit point (the tap) would be exposed to any significant amount of the contaminant and experience adverse health effects.

PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

Introduction

The contaminants of concern released into the environment at the ICG Iselin Railroad Yard site have the potential to cause adverse health effects. However, for adverse health effects to occur the pathway for exposure must be completed. A release does not always result in exposure. A person can only be exposed to a contaminant if they come in contact with the contaminant. Health effects resulting from the interaction of an individual with a hazardous substance in the environment depend on several factors. One is the route of exposure: that is, whether the chemical is breathed, consumed with food, soil, or water, or whether it contacts the skin. Another factor is the dose to which a person is exposed, and the amount of the exposure dose that is actually absorbed. Mechanisms by which chemicals are altered in the environment or inside the body, as well as the combination (types) of chemicals are also important. Once exposure occurs, characteristics such as age, sex, nutritional status, genetics, life style, and health status of the exposed individual influence how the contaminants are absorbed, distributed, metabolized, and excreted. Together those factors and characteristics determine the health effects that may occur as a result of exposure to a contaminant. Much variation in those mechanisms exists among individuals. For example; all children mouth or ingest nonfood items to some extent. The degree of pica behavior varies widely in the population, and is influenced by nutritional status and the quality of care and supervision (12). Groups that are at increased risk for pica behavior are children aged 1 to 3 years old, children from families of low socioeconomic status, and children with neurologic disorders (e.g., brain damage, epilepsy, and mental retardation).

Health Guidelines

Health guidelines provide a basis for comparing estimated exposures with concentrations of contaminants in different environmental media (soil, air, water, and food) to which people might be exposed.

Non-Cancer Health Effects

ATSDR has developed a Minimal Risk Level (MRL) for contaminants commonly found at hazardous waste sites. The MRL is an estimate of daily exposure to a contaminant below which non-cancer, adverse health effects are unlikely to occur. MRLs are developed for different routes of exposure, like inhalation and ingestion, and for length of exposure, such as acute (less than 14 days), intermediate (15 - 364 days), and chronic (365 days or greater). Oral MRLs are expressed in units of milligrams of contaminant per kilogram of body weight per day (mg/kg/day). Because ATSDR has no methodology to determine amounts of chemicals absorbed through the skin, the Agency has not developed MRLs for dermal exposure. The method for deriving MRLs does not include information about cancer, therefore, an MRL does not imply anything about the presence, absence, or level of cancer risk. If an ATSDR MRL is not available as a health value, then EPA's Reference Dose (RfD) is used. The RfD is an estimate of daily human exposure to a contaminant for a lifetime below which (non-cancer) health effects are unlikely to occur (12).

Cancer Health Effects

The Environmental Protection Agency (EPA) classifies chemicals as Class A, Class B, Class C, Class D, or Class E. This classification defines a specific chemical's ability to cause cancer in humans and animals. According to EPA, Class A chemicals are known human carcinogens, and Class B chemicals are probable human carcinogens. Class B is further subdivided into two groups: Group B1 consists of chemicals for which there is limited evidence of carcinogenicity from epidemiologic studies in humans; and Group B2 consists of chemicals for which there is sufficient evidence of carcinogenicity in animals, but inadequate evidence or no data available from epidemiologic studies in humans. Group C chemicals are possible human carcinogens. Group D chemicals are not classifiable as to human carcinogenicity and Group E chemicals are those for which there is evidence that they are not carcinogenic to humans. For carcinogenic substances, EPA has established the Cancer Slope Factor (CSF) as a guideline. The CSF is used to determine the number of excess cancers resulting from exposure to a contaminant. The National Toxicology Program in its Annual Report on Carcinogens classifies a chemical as a "known human carcinogen" based on sufficient human data. Its classification of a chemical as being "reasonably anticipated to be a carcinogen" (RAC) is based on limited human or sufficient animal data. ATSDR considers the above physical and biological characteristics when developing health guidelines.

Exposure Dose Estimation

To link the site's human exposure potential with health effects that may occur under site-specific conditions, ATSDR estimates human exposure to the site contaminant from ingestion and/or inhalation of different environmental medium (12). The following relationship is used to determine the estimated exposure to the site contaminant:

      ED = (C x IR x EF) / BW

where:

    ED = exposure dose (mg/kg/day)
    C = contaminant concentration
    IR = intake rate
    EF = exposure factor
    BW = body weight

Standard body weights for adults, young children, and toddlers are 70 kg, 16 kg and 10 kg, respectively. The maximum contaminant concentration detected at a site for a specific medium is used to determine the estimated exposure. Use of the maximum concentration will result in the most protective evaluation for human health. For soil the ingestion rates used are 50 mg/day for adults, 200 mg/day for school-aged children off-site exposures, and 100 mg/day for on-site workers and trespassers. Exposure doses for children exhibiting pica behavior were evaluated for soils off-site in the vicinity of the Washington-Douglas Elementary School because the school now houses a headstart program. A small child (aged 1 to 3 years old) may on occasion ingest 5000 mg/day (one teaspoon per day) of contaminated soil. Some exposures are intermittent or irregularly timed. For those exposures, an exposure factor (EF) is calculated which averages the dose over the exposed period. When unknown the biological absorption from the environmental media (soil, water) is assumed to be 100%.

How Risk Estimates are Made

Non-Cancer Risks

For noncarcinogenic health risks, the contaminant intake was estimated using exposure assumptions for the site conditions. This dose was then compared to a risk reference dose (estimated daily intake of a chemical that is likely to be without an appreciable risk of health effects) developed by ATSDR or EPA.

Noncarcinogenic effects unlike carcinogenic effects are believed to have a threshold, that is, a dose below which adverse effects will not occur. As a result, the current practice is to identify, usually from animal toxicology experiments, a no-observed-adverse-effect-level (NOAEL), This is the experimental exposure level in animals at which no adverse toxic effect is observed. The NOAEL is then divided by an uncertainty factor (UF) to yield a risk reference dose. The UF is a number which reflects the degree of uncertainty that exists when experimental animal data are extrapolated to the general human population. The magnitude of the UF takes into consideration various factors such as sensitive sub-populations (for example, children, pregnant women, and the elderly), extrapolation from animals to humans, and the incompleteness of available data. Thus, exposure doses at or below the risk reference dose are not expected to cause adverse health effects because it is selected to be much lower than dosages that do not cause adverse health effects in laboratory animals.

 

The measure used to describe the potential for non-cancer health effects to occur in an individual is expressed as a ratio of estimated contaminant intake to the risk reference dose. If exposure to the contaminant exceeds the risk reference dose, there is concern for potential non-cancer health effects. As a rule, the greater the ratio of the estimated contaminant intake to the risk reference dose, the greater the level of concern. A ratio equal to or less than one is generally considered an insignificant (minimal) increase in risk.

Cancer Risks

Increased cancer risks were estimated by using site-specific information on exposure levels for the contaminant of concern and interpreting them using cancer potency estimates derived for that contaminant by EPA. An increased excess lifetime cancer risk is not a specific estimate of expected cancers. Rather, it is an estimate of the increase in the probability that a person may develop cancer sometime in his or her lifetime following exposure to that contaminant.

There is insufficient knowledge of cancer mechanisms to decide if there exists a level of exposure to a cancer-causing agent below which there is no risk of getting cancer, namely, a threshold level. Therefore, every exposure, no matter how low, to a cancer-causing compound is assumed to be associated with some increased risk. As the dose of a carcinogen decreases, the chance of developing cancer decreases, but each exposure is accompanied by some increased risk.

There is no general consensus within the scientific or regulatory communities on what level of estimated excess cancer risk is acceptable. Some have recommended the use of the relatively conservative excess lifetime cancer risk level of one in one million because of the uncertainties in our scientific knowledge about the mechanism of cancer. Others feel that risks that are lower or higher may be acceptable, depending on scientific, economic and social factors. An increased lifetime cancer risk of one in one million or less is generally considered an insignificant increase in cancer risk.

Sources of Health Guideline Information

ATSDR has prepared toxicological profiles for many substances found at hazardous waste sites. Those documents present data and interpret information on the substances. Health guidelines, such as ATSDR's MRL and EPA's RfD and CSF are included in the toxicological profiles. Those health guidelines are used by ATSDR health professionals in determining the potential for developing adverse non-carcinogenic health effects and/or cancer from exposure to a hazardous substance. Preparers of this public health assessment have reviewed the profiles for the contaminants of concern at the ICG Iselin Railroad Yard site.

How Risks at the ICG Iselin Railroad Yard Site are Estimated

ATSDR has identified both on-site and off-site completed exposure pathways (Appendix D, Tables 1 and 2). Individuals were most likely exposed to multiple contaminants by incidental ingestion, dermal contact, and incidental ingestion of surface soil, surface water, and sediments. People were also exposed to contaminants in ambient air. Data are very limited on the health effects of multiple contaminant exposure. The effects of multiple contaminant exposure can be additive, synergistic (greater than the sum of the single contaminant exposures), or antagonistic (less than the sum of the single contaminant exposures). Also, simultaneous exposure to contaminants that are known or probable human carcinogens could increase the risk of developing cancer. ATSDR's evaluation of exposures in this public health assessment is limited to individual contaminant exposures; multiple exposures have not been evaluated.

The railyard is active and metal fabrication facilities are currently located on the site. Due to these activities, ATSDR considers workers in these operations as well as to trespassers to be likely exposed. Until the contaminated media to which these individuals may become exposed is remediated or removed, these exposures are believed to continue. It should be noted that current concentrations of VOCs in soils is not always indicative of past concentrations in soil and therefore, current exposure is not necessarily indicative of past exposure. Past exposures may not be quantifiable. The completed exposure pathways discussed are our best estimates of possible scenarios based what we know about the history of the site.

Because of uncertainty regarding duration of exposures for most populations, ATSDR is using the following worse case scenario: 1) all exposed populations visited or worked on the site at least five days per week for fifty weeks; 2) the maximum level of contamination in soil samples taken at 0"-6" was accessible to all exposed populations; and 3) 100% of the contaminant could be absorbed. This is a very conservative estimate since the amount of a chemical absorbed depends on many things including the route by which the contaminant comes into contact with the body and the type of chemical. It is also assumed that workers are exposed for a period of thirty years and trespassers/visitors are/were exposed for a period of no more than 25 years on an intermittent basis. This will allow for the greatest protection of public health.

For those contaminants which ATSDR has established health guidelines, no one was exposed to the contaminants above levels of health concern, based upon the estimated exposure doses (even by using the very conservative assumptions detailed above). Contaminants which are carcinogenic and those for which there are no health guidelines available will be discussed further (see Appendix D, Tables 1 and 2). Although the municipal wells are considered a potential pathway, PCE will be discussed because of concerns expressed by regulatory officials.

Discussion of Contaminants of Concern

2-Hexanone (14)

2-Hexanone, also known as methyl n-butyl ketone is a clear, colorless liquid that can easily evaporate into the air as a vapor. It was used in the past in paint and paint thinner, to make other chemical substances, and to dissolve oils and waxes. It is a waste product of wood pulping, coal gasification, and oil shale operations. It is no longer manufactured in the U.S. and most likely breaks down into smaller products within a few days of being released into water, air, or soil.

2-Hexanone has been found in on-site soils and on-site surface waters. The maximum levels were found in the tank car loading area and in the intermittent tributary near the Jones Creek discharge point at concentrations of 0.014 mg/kg and 0.082 mg/l, respectively. ATSDR has not developed any MRLs and EPA has not developed an RfD for 2-hexanone. The inhalation lowest observed adverse effect level (LOAEL) for humans breathing the contaminant for less than one year is 9 parts per million (ppm). 2-Hexanone was not detected above detection limits in the air samples collected during the remedial investigation. The oral and dermal LOAEL (100 mg/kg/day) is based on a study with hens exposed for a period of less than one year. This dose is many orders of magnitude higher than the estimated exposure dose. Therefore adverse health effects due to exposure are not expected to have occurred in any of the target populations.

It is not known if 2-hexanone causes cancer in animals and humans. No population unusually susceptible to the toxic effects of 2-hexanone exposure have been identified.

2-Methylnaphthalene and Naphthalene (15)

Naphthalene is a solid white substance that smells like tar or mothballs. It evaporates easily and when mixed with air also burns easily. Naphthalene does not readily stay in soils or sediments. In soil, naphthalene is either destroyed by bacteria or it evaporates into the air within a few hours or days. Naphthalene is a natural component of coal and petroleum. While it is used for making dyes, resins, carbaryl, and leather tanning agents; the most common household products made from naphthalene are mothballs and toilet deodorant blocks. Very little information is known about 2-methylnaphthalene. It is solid at room temperature and is used to make other chemicals and to make pesticides. Both are present in asphalt, cigarette smoke, tar, and wood smoke.

Naphthalene, which may not have an unpleasant smell, can be detected in air at a concentration of 0.084 ppm and in water at a concentration of 0.021 mg/l. A related compound, 2-methylnaphthalene can be detected in air and water at concentrations of 0.010 ppm and mg/l, respectively. According to studies, the typical average indoor air concentration for these contaminants is less than 0.001 ppm. It is unlikely that a person would come into contact with the contaminants from food brought from a store.

Naphthalene and 2-methylnaphthalene were detected in soils at the tank car loading area at maximum concentrations of 32 mg/kg and 94 mg/kg, respectively. The concentration of naphthalene is nearly twice the concentration found in soil from a former tar-oil refinery. The most common way to be exposed to these chemicals is via inhalation or ingestion. The inhalation MRL for naphthalene is 0.002 ppm. Neither naphthalene nor 2-methylnaphthalene were part of the parameters for which the air samples reviewed to date were analyzed. The intermediate oral MRL for naphthalene is 0.02 mg/kg/day. The estimated exposure dose using the worse case scenarios is 100,000 times lower than the MRL. No adverse non-carcinogenic health effects are expected to have occurred from incidental ingestion of this contaminant.

ATSDR has no MRLs and EPA has no RfD for 2-methylnaphthalene. In addition, no studies were located which thoroughly examined the adverse health effects resulting from long-term exposure via dermal contact, inhalation, or ingestion to 2-methylnaphthalene.

The cancer effect level (CEL) is the lowest dose of a chemical in a study, or group of studies that produces significant increases in the incidence of cancer (or tumors) between the exposed population and its appropriate control population. The CEL for naphthalene via inhalation is 30 ppm and was based upon a mouse study. The female mice experienced pulmonary alveolar adenomas, a type of respiratory cancer. However, EPA has determined that naphthalene is not classifiable as to its carcinogenicity to humans. Although naphthalene was not one of the parameters tested during air sampling, based upon the levels in the soil, ATSDR does not believe that cancer is a possible outcome from exposure via inhalation.

Human infants appear to be more sensitive to the effects of naphthalene than adult humans. This may be due to limited mobility and less-developed metabolic conjugation pathways. Since the contaminant was found in on-site soil, ATSDR does not believe that infants would be exposed to the contaminant. The hemolytic response to naphthalene is enhanced by the presence of inherited erythrocyte G6PD deficiency. Although any human may experience acute hemolysis if exposed to sufficiently high doses of naphthalene, this enzyme deficiency may cause some persons to be unusually sensitive. The incidence of the deficiency among Caucasians of European origin is relatively low, while there is a higher incidence among certain groups of Asians and Middle Eastern populations. A study of hemolytic anemia in African-American children with G6PD deficiency suggested that this is a population that may be susceptible to the hemolytic effects of naphthalene exposure.

Data indicating whether or not there are any populations with high susceptibility to the effects of 2-methylnaphthalene exposure were not located.

4-Methyl-2-pentanone (16)

4-Methyl-2-pentanone (MIBK), also known as methyl isobutyl ketone is a colorless liquid with a pleasant, camphor-like odor. MIBK is used as a denaturant for rubbing alcohol and as a solvent for paint and varnishes. It is also used in manufacturing dry-cleaning preparations and the extraction of uranium from fission products. MIBK is released into the environment via effluent and emissions from facilities that use and produce it, in exhaust gas from vehicles, via leaching, and from land or ocean disposal of consumer products and industrial wastes.

MIBK was detected in the surface waters of the intermittent tributary near its discharge point to Jones Creek at a maximum concentration of 0.026 mg/l. The most probable routes of MIBK exposure are via inhalation and dermal contact. The compound was not detected during the limited air sampling that was conducted during the initial remedial investigation. Incidental ingestion may also occur. ATSDR has not developed MRLs and EPA has not developed an RfD for MIBK. ATSDR does not have a toxicological profile for MIBK, therefore, a literature search was done to locate relevant studies. The studies reviewed examined exposure to MIBK at higher levels than the concentration detected. Most of these studies showed MIBK to be neurotoxic. However, based upon the reviewed studies, it appears that noncarcinogenic health effects should not occur in persons exposed intermittently at the maximum concentration detected.

4-Methyl-2-pentanone has not been tested for its ability to cause cancer in animals and unusually sensitive populations were not identified.

Carbazole (16)

Carbazole also known as dibenzo(b,d)pyrrole (a heterocyclic, polyaromatic hydrocarbon ) that is naturally contained in coal, petroleum, and peat. It is an important dye intermediate for making photographic plates sensitive to ultraviolet light. It is used as an odor inhibitor in detergents and in the manufacturing of insecticides and lubricants. Carbazole is released into the environment via combustion of rubber, petroleum, coal, and wood; and emissions from waste incineration, tobacco smoke, and aluminum manufacturing.

Carbazole has been identified in cigarette smoke at a concentration of 1 microgram per cigarette. Most human exposure (non-occupational) occurs through the smoking of cigarettes and the inhalation of contaminated air. Carbazole also can be found in foods as a result of char-broiling.

Carbazole was found in the soils near the rail tie pile at an estimated maximum concentration of 0.34 mg/kg. Carbazole usually has low mobility in soil. ATSDR has no MRLs and EPA has no RfD for this compound. ATSDR does not have a toxicological profile for carbazole. A literature search did not reveal any relevant information. Therefore, it is not possible to determine whether any adverse health effects are/were likely for exposure to the carbazole in the contaminated soil at the estimated exposure doses.

Dibenzofuran (16)

Dibenzofuran is an organic compound that contains two benzene rings fused to a central furan ring. It is a white, crystalline powder derived from coal tar and is used to make other chemicals and as an insecticide. It is released into the environment in atmospheric emissions involved with the combustion of biomass, refuse, and diesel fuels. The incomplete combustion of propane has been found to form dibenzofuran.

Dibenzofuran was detected in the soils of the tank car loading/unloading area at a maximum concentration of 3.5 mg/kg. ATSDR has no MRLs and EPA has no RfD for this compound. ATSDR has not developed a toxicological profile for dibenzofuran. Epidemiological and experimental data are needed in order for ATSDR to determine whether adverse health effects may have occurred from exposure to dibenzofuran at the maximum concentration detected.

Dibenzofuran has not been tested for its ability to cause cancer in animals. However, it is derived from coal tar which is a substance that causes cancer in humans. It is not known if dibenzofuran itself causes cancer.

Unusually susceptible populations were not identified.

Dieldrin (17)

Dieldrin is a white powder that was once used as an ingredient in insecticides. The chemical is no longer used. From the 1950's until 1970, dieldrin was used extensively as a insecticide on crops such as cotton and corn. The U.S. Department of Agriculture canceled all uses of dieldrin in 1970. In 1972, however, EPA approved for the killing of termites. Use of the chemical to control termites continued until 1987 when the manufacturer voluntarily canceled the registration for its use.

Most dieldrin in the environment is found in soil and animal fat. Background levels of dieldrin in soil are about 0.001 mg/kg. This is about 1000 times higher than background levels in air and water. The estimated daily intake of dieldrin from air is 0.02 nanogram per kilogram of body weight (0.02 ng/kg/day). The 1982-1984 estimated daily intake from food was 10 ng/kg/day for infants and 16 ng/kg/day for young children. The daily food intake for adults was 7-8 ng/kg/day. One nanogram is one million times less than one milligram.

Dieldrin was detected in soils from the battery storage area and sediments in the intermittent stream (downstream of the old floor drainage system discharge point) at a maximum concentration of 0.46 mg/kg and 0.06 mg/kg, respectively. Exposure to dieldrin may have occurred via inhalation or dermal contact because dieldrin is volatile from contaminated surfaces. Dieldrin was not one of the parameters for which air samples taken during the initial remedial investigation were analyzed. Exposure may have also occurred via incidental ingestion of the contaminated medium. ATSDR's chronic, oral MRL for dieldrin is 0.00005 mg/kg/day. The estimated oral exposure doses do not exceed the MRL, therefore, adverse non-carcinogenic health effects are not expected to have occurred due to incidental ingestion of the contaminated media.

EPA has classified dieldrin as a Class B2 probable human carcinogen based upon animal studies. The cancer slope factor for dieldrin is 16 (mg/kg/day)-1 and the CEL based upon animal studies is 0.013 mg/kg/day. The estimated exposure doses are many orders of magnitude lower than the CEL. Therefore, carcinogenic health effects are not expected to occur.

It is suspected that the elderly with declining organ function and the youngest of the population with immature and developing organs will generally be more vulnerable to the toxic effects of dieldrin than healthy adults. Persons with immature hepatic detoxification systems, persons with impaired liver function, and persons with impaired immune function are potentially more likely to demonstrate unusual sensitivity to the effects of exposure to dieldrin. Review of literature regarding toxic effects of dieldrin did not reveal any populations that are known to be unusually sensitive to dieldrin.

Methylene Chloride (18)

Methylene chloride, also known as dichloromethane, is a colorless liquid that has a sweet odor. It is widely used as an industrial solvent and as a paint stripper. It can be found in certain aerosol and pesticide products and is used in the manufacture of photographic film. The chemical may be found in some spray paints, automotive cleaners, and other household products. Methylene chloride does not appear to occur naturally in the environment.

People can smell methylene chloride at about 56 mg/m3 in air. Because people differ in their ability to smell various chemicals, odors may not be helpful in avoiding over-exposure. Methylene chloride has not been shown to cause cancer in humans exposed to vapors in the workplace.

During the SRI methylene chloride was detected in ambient air samples taken upwind of the site at a maximum concentration of 0.023 mg/m3. The NOAEL for humans via inhalation exposure is 280 mg/m3. No adverse non-carcinogenic effects are expected to occur in populations exposed to methylene chloride in ambient air at the maximum concentration detected upwind of the site.

Methylene chloride is classified as a probable human carcinogen based upon animal data by the EPA. Several epidemiological studies have detected no excess risk of death from malignant neoplasms in workers exposed to methylene chloride at levels up to 133 mg/m3.

Tetrachloroethene (19)

Tetrachloroethene (PCE) is a synthetic chemical used for dry cleaning fabrics and metal- degreasing operations. It evaporates in air and has a sharp, sweet odor.

Although it is not believed site-related, PCE was detected in JUD well #06 at a maximum concentration of 0.004 mg/l during the RI. That concentration is less than the MCL of 0.005 mg/l. The sample was taken at the well itself and not from a household tap. The water is mixed with water from uncontaminated wells before reaching the end-user. Even if a person were to ingest 2 liters of water containing the maximum concentration detected on a daily basis, no adverse non-carcinogenic or carcinogenic health effects would be expected to occur.

Carcinogenic Polycyclic Aromatic Hydrocarbons (20)

Polycyclic aromatic hydrocarbons (PAHs) are found ubiquitously in the environment from both man-made and natural sources, as complex mixtures. These products include fossil fuels; cigarette smoke; industrial processes (such as coke production, refinement of crude oil); and exhaust emissions from gasoline engines, oil-fired heating, and burnt coals. PAHs generally exist as colorless, white or green solids. Some are used in medicines and in the production of dyes, plastics, and pesticides.

Polycyclic aromatic hydrocarbons are found in foods, particularly charbroiled, broiled, or pickled food items, and refined fats and oils. The typical U.S. diet contains less than 0.002 mg PAHs/kg food. Levels of PAHs (benzo(a)pyrene) have been detected in cooked (char-broiled) foods as great as 60 mg/kg. This level exceeds the concentration found in the on-site soils. People can be exposed to PAHs via tobacco smoke, smoke from wood fires, and creosote-treated wood products.

Carcinogenic PAHs were found in on-site soils at a maximum concentration of 6.45 mg/kg near the rail tie pile dump and in on-site sediments of the drainage ditch at a maximum concentration of 5.61 mg/kg. PAHs can enter the body via dermal contact, ingestion, and inhalation, however, absorption is generally slow when PAHs are swallowed. These compounds were not part of the parameters for which the air samples taken during the initial remedial investigation were tested. EPA and others have developed a relative potency estimate approach for the PAHs. By using this approach, the cancer potency of the other carcinogenic PAHs can be estimated based upon their relative potency to benzo(a)pyrene (BaP). In order to calculate the exposure dose and evaluate the possible carcinogenic health effects for these PAHs, ATSDR converted the concentrations to BaP equivalents. The equivalents were summed and an exposure dose was calculated. No acute or chronic oral MRLs were derived for PAHs because there are no adequate human or animal dose-response data available that identify threshold levels for appropriate non-cancer effects. An intermediate MRL has been derived. The estimated oral exposure doses for the carcinogenic PAHs were many orders of magnitude less than the health guideline of 0.1 mg/kg/day, therefore, non-carcinogenic adverse health effects are not expected to have occurred due to incidental ingestion of the soils and sediments at these maximum concentrations.

EPA has classified carcinogenic PAHs as Class B2 probable human carcinogens based upon animal studies. Although there are insufficient human studies, evidence exists to indicate that mixture of PAHs are carcinogenic to humans. This evidence comes primarily from occupational case studies of workers exposed to mixtures containing PAHs as a result of their involvement in such processes as coke production, roofing, oil refining, or coal gasification. A quantitative cancer risk estimate has thus far been developed for BaP. The cancer slope factor for BaP is 7.3 (mg/kg/day)-1 and is based on the geometric mean of risk estimates calculated from previous studies. The CEL for PAHs, based on animal studies, is 0.15 mg/kg/day. The estimated exposure doses for both on-site workers and trespassers are many orders of magnitude lower than the CEL. Therefore, carcinogenic health effects are not expected to occur.

Data indicate that specific subsections of the population may be susceptible to the toxic effects produced by exposure to PAHs. People with the genetic ability to induce aryl hydrocarbon hydrolase (AHH), a microsomal enzyme believed to be responsible for the metabolism of BaP, are more susceptible to the carcinogenic effects of exposure to PAHs. People who undergo rapid reduction of body fat may be at risk from increased toxicity because of the systemic release and activation of PAHs that had been stored in fat. Other subsections of the population that may be susceptible to the toxic effects of PAHs are people who smoke, people with a history of excessive sun exposure, people with liver and skin diseases, and women, especially those of child-bearing age.

Aluminum (21)

Aluminum is a silver-white, flexible metal and is found naturally in the earth combined with other elements. It makes up approximately 8% of the earth's surface. Combined with other compounds, it is commonly used in deodorants, antacids, and for the treatment of drinking water. In the metallic form it is used to form appliances, cooking utensils, and building materials.

Aluminum was detected on-site sediment of the drainage ditch on the east side of the site at a maximum concentration of 1870 mg/kg. It was detected off-site in the terrace area soils and in the sediments of Jones Creek at maximum concentrations of 4720 mg/kg and 12200 mg/kg, respectively. At the estimated exposure doses, adverse non-carcinogenic health effects, following long-term exposure to aluminum at the maximum concentrations detected, are not expected to occur.

Aluminum has not been classified for carcinogenicity. No studies were located regarding cancer in humans or animals following chronic exposure via ingestion of or dermal contact with aluminum or its compounds. The studies regarding cancer following inhalation exposure to aluminum or its compounds were inconclusive due to the addition of other variables which could have contributed to the development of the carcinogenic effect. The available information has not shown that aluminum is a potential carcinogen.

Patients on dialysis are subject to two syndromes that may be associated with aluminum, dialysis encephalopathy and renal osteodystrophy. Aluminum is not actually known to cause either one of the syndromes. Patients with Alzheimer's disease may be more vulnerable to the effects of aluminum than other people.

Arsenic (22)

Arsenic is a metal-like material usually found in the environment combined with other elements. Arsenic when combined with carbon and hydrogen is referred to as organic arsenic. Arsenic combined with other elements such as oxygen, chlorine, and sulphur is referred to as inorganic arsenic. The organic forms of arsenic are usually less harmful than the inorganic forms. Inorganic arsenic occurs naturally in many kinds of rocks, especially those containing copper and lead ores. The main use of arsenic is as a wood preservative to make the wood resistant to rotting and decay. Arsenic is also used as an ingredient in insecticides and herbicides. Arsenic is not broken-down or destroyed in the environment, but it will readily change from one valence state to another by natural chemical reactions.

Arsenic occurs naturally in soils in concentrations of approximately 5 mg/kg (the average concentration in soils of the eastern United States (23)). Most arsenic-induced toxicity in humans is due to exposure to inorganic arsenic. In the United States the average adult consumes 0.05 mg/day of arsenic in their diet. Food is usually the largest source of arsenic exposure in humans.

Arsenic was detected in soil samples taken north of the air brakes maintenance building and in sediment samples from the intermittent tributary downstream of the lye vat at maximum concentrations of 84.7 mg/kg and 39.8 mg/kg, respectively. Arsenic was not detected above detection limits during the limited air sampling that occurred during the initial remedial investigation. It was also found in the off-site soils and in off-site sediments at a maximum concentration of 3.2 mg/kg each. The chronic oral MRL for arsenic is 0.0003 mg/kg/day. The estimated exposure doses did not exceed the MRL. Therefore, adverse non-carcinogenic health effects are not expected to have occurred to on-site workers and trespassers nor residents due to these exposures.

Relatively little information is available on adverse health effects due to direct dermal contact with inorganic arsenicals, but several studies indicate that the chief effect is local irritation and dermatitis, with little risk of other adverse effects. The dermal contact rates which cause these effects in humans have not been quantified, but a similar type of irritation was produced on mice exposed to 2.5 mg arsenic/kg as sodium arsenite.

EPA classifies arsenic as a Class A known human carcinogen by the oral and inhalation routes. Epidemiologic studies of people exposed to arsenic in Taiwan indicate that exposure to arsenic is associated with skin cancer. Based on that and other studies, the EPA considers arsenic to be a human carcinogen. The EPA has calculated a cancer unit risk factor, 1.5 (mg/kg/day)-1, which can be used to estimate the probability of excess cancer risk for a lifetime of exposure to arsenic. Cancer risks for exposure were estimated based on the maximum concentration of arsenic in the contaminated media. The CEL for arsenic in humans is 0.009 mg/kg/day. The CEL is over 1000 times greater than the estimated exposure doses. The chance of developing cancer based upon the risk and exposure dose estimations for the target populations is unlikely.

No studies were found regarding unusual susceptibility of any human sub-population to arsenic. Since the degree of arsenic toxicity may be influenced by the rate and extent of its methylation in the liver, it seems likely that some members of the population might be especially susceptible because of the lower than normal methylating capacity. This reduced capacity could result from dietary deficiency of methyl donors such as choline or methionine. Liver disease does not appear to decrease methylation capacity in humans, at least not at low levels of arsenic exposure.

Cadmium (24)

Cadmium (Cd) is a naturally occurring element that is usually found combined with other metals. Cd is currently used for the production of nickel-cadmium (Ni-Cad) batteries and for metal plating. It is also used for pigments, plastics, synthetics, and for alloys.

Foodstuffs are the most important source of Cd exposure for the general population. Low levels of Cd can be found in basic foods such as potatoes, grains, cereals, and leafy vegetables. The amount of Cd absorbed from smoking one pack of cigarettes per day is about 1-3 micrograms of Cd per day (µg/day), roughly the same as in the diet. The Food and Drug Administration (FDA) limits the amount of Cd in food colors to 15 mg/l. In the United States, the average person consumes about 30 µg/day of Cd in their diet.

Cd, a cumulative toxicant, was detected in soil samples taken north of the air brakes maintenance building and in sediments from the intermittent tributary downstream of the old floor drainage system discharge point at maximum concentrations of 5.2 mg/kg and 14.5 mg/kg, respectively. Cd was not detected in air samples taken during the initial remedial investigation. The chronic oral MRL for Cd is 0.007 mg/kg/day. The estimated oral exposure doses did not exceed the MRL. Adverse non-carcinogenic health effects due to ingestion and inhalation are not expected to have occurred. Little information is presently available to judge the potential absorption or toxicity of Cd from dermal exposure.

EPA classifies Cd as a B1 probable human carcinogen via inhalation. There is weak evidence of increased lung cancer in humans from breathing Cd (at high levels). There is strong evidence that Cd causes cancer in animals via the inhalation route of exposure. Studies in humans and animals that ate or drank Cd did not show an increased risk of developing cancer. The inhalation CEL for Cd is 0.03 milligrams per cubic meter. Cd was not detected above detection limits during the limited air sampling that occurred during the initial remedial investigation. Neither human nor animal studies, to date, provide sufficient evidence to determine whether or not Cd is a carcinogen by the oral route.

Populations with depleted stores of calcium, iron, or other dietary components due to multiple pregnancies and/or dietary deficiencies would be expected to have increased Cd absorption from the gastrointestinal tract and a greater concentration of Cd in the bones. Populations with kidney damage from causes unrelated to Cd exposure, including people with diabetes and the natural age-related decline in kidney function, would be expected to exhibit nephrotoxicity at lower Cd exposures than healthy adults.

Chromium (25)

Chromium is a naturally occurring element found in rocks, soil, plants, animals, and in volcanic dusts and gases. Chromium VI, the form of chromium that is known to cause cancer in humans through inhalation, occurs rarely in the natural environment. Chromium compounds have no taste or odor. Chromium is used for making steel and other alloys, bricks in furnaces, and dyes and pigments. It is also used for chrome plating, leather tanning, and wood preserving.

Chromium III is a essential nutrient required for normal energy metabolism. The National Research Council (NRC) recommended in its 1989 report a dietary intake of 50-200 µg/day. Chromium III is believed to assist insulin in maintaining normal glucose levels. The general population is exposed to chromium by inhaling ambient air, ingesting foods, and drinking water containing chromium. Dermal exposure of the general public to chromium can occur from skin contact with certain consumer products or soils that contain chromium. United States soil levels of total chromium range from 1.0 to 2,000 milligrams chromium per kilogram soil (1-2000 mg/kg), with a mean level of 37 mg/kg. Chromium content of foods varies greatly and depends on the processing and preparation.

Chromium was detected in the soil near the fueling shed (198 mg/kg). Chromium was not detected above detection limits during the initial remedial investigation air sampling. The estimated oral exposure doses for chromium in soil, do not exceed the health guidelines of 0.005 mg/kg/day (chromium VI) and 1.0 mg/kg/day (chromium III), therefore, adverse non-carcinogenic health effects are not expected to have occurred to on-site workers and trespassers.

Chromium was detected in the sediments of the intermittent tributary, just east of the rail tie pile dump, at a maximum concentration of 1950 mg/kg. The average concentration of chromium in off-site sediments is approximately 410.7 mg/kg. Since there is not enough water in the tributary for swimming, the activity most likely to lead to exposure is wading. Based upon the worse case scenario, the estimated exposure doses for incidental ingestion of the contaminated sediments at the maximum concentration do not exceed the health guidelines. However, the most likely route for exposure would be through dermal contact. Chromium VI is better absorbed from the skin than is chromium III. Some chromium VI compounds are very caustic and can cause severe burns upon dermal contact. These burns could facilitate the absorption and lead to systemic toxicity.

EPA has classified chromium VI as a Class A known human carcinogen by the inhalation route. Laboratory studies have not shown that chromium VI or chromium III cause cancer in animals when ingested. The form of chromium found at the site is not known. ATSDR does not have enough data to determine if chromium III is carcinogenic. No studies were located regarding cancer in humans or animals after dermal exposure to chromium or its compounds. However, even assuming that the chromium at the site is chromium VI (a very worse-case conservative assumption), there is no increased risk of cancer associated with the ICG Iselin Railroad Yard NPL site. Although chromium III is an essential nutrient, based upon occupational studies, exposure to high levels may cause some adverse health effects. Information regarding adverse health effects due to dermal contact with high concentrations of chromium III in a non-occupational setting was not located.

Acute inhalation lethal concentration and oral and dermal lethal dose studies suggest that female animals are more sensitive to the lethal effects of chromium VI compounds. Whether human females are more sensitive than males to toxic effects of chromium or its compounds is not known. Other information identifying possible susceptible populations was not found. Some individuals who are sensitive to chromium may develop asthma as a allergic response to inhaled chromium. This effect is not expected to occur in the possibly exposed populations at this site since chromium was not detected in the air samples taken during the remedial investigation.

Copper (26)

Copper (Cu), a reddish-brown metal which occurs naturally in rocks, soils, water, plants, sediment, air, and animals (including humans), is an essential element for all known living organisms. Some common uses of Cu is to make electrical wires, the U.S. penny, and some water pipes. It is also combined with other metals to form the alloys brass and bronze. Soil generally contains between 2 and 250 mg/kg Cu although concentrations close to 7000 mg/kg have been found near Cu production facilities. The average concentration of Cu in tap water ranges from 0.02 to 0.075 milligrams Cu per liter water (mg/l). However, many households have Cu concentrations of over 1 mg/l. The average person consumes one mg/day of Cu in food and drink. Cu rapidly enters the bloodstream and is distributed throughout the body after ingestion. The body can excrete Cu after acute exposure to high concentrations via vomiting or diarrhea. This mechanism helps block Cu from entering the blood. It is not known how much Cu enters the body via dermal contact. Information regarding adverse health effects due to chronic dermal exposure was not located.

Cu was detected in the soils near the office/storage building and in the sediments of Jones Creek and the intermittent tributary downstream of the lye vat. The maximum concentrations detected were 801 mg/kg, 256 mg/kg, and 474 mg/kg, respectively. ATSDR has not developed MRLs and EPA had not developed an RfD for the ingestion of Cu. There is little information on Cu toxicity in man. Most of the reports of Cu toxicity in humans involves acute exposure and the consumption of water containing large amounts of Cu or suicide attempts using copper sulfate. Long-term exposure of humans to Cu by ingestion and dermal contact occurs in occupational settings as well as the home. However, there is limited information on effects of chronic Cu exposure. Long-term exposure at an exposure dose of approximately 0.056 mg/kg/day has resulted in abdominal pain or vomiting. This dose is about 100 times greater than the estimated dose for a child consuming on-site soils via incidental ingestion. Because exposures were likely intermittent, ATSDR estimates that these non-carcinogenic effects would have been minimal, if any. Cu was not detected in the air samples taken during the remedial investigation.

Cu is not known to cause cancer.

Wilson's disease is a rare hereditary disease caused by a defect in the body's ability to metabolize copper. As a result copper deposits accumulates in organs such as brain, kidneys, and liver. Therefore, individuals with Wilson's disease are unusually susceptible to Cu toxicity because of their impaired ability to maintain normal Cu homeostasis. Limiting Cu intake through air, water, and food, and special medical treatment is essential in treating the disease. In addition, infants and children less than one-year old and persons with liver damage may be more susceptible to Cu toxicity.

Iron (16)

Iron (Fe) is a soft, malleable, grayish metal. It can be black or gray in the powder form. It is the second most abundant metal in earth's crust (second to aluminum) and is the fourth most abundant element.

Fe is an essential trace element that is needed to make blood and other Fe-containing proteins. Most of the Fe in the body is recycled, but humans need about 1.2 mg/day of new Fe to replace that which is lost through the intestinal mucosa cells as they are sloughed off. Generally about 10% of ingested Fe is absorbed, making the average nutritional requirement about 12 mg/day. Growing children and women need about 15-18 mg/day. Pregnant women require even more Fe and many are given ferric sulfate as a supplement.

Fe (1850 mg/kg - 136000 mg/kg) was detected in the sediments of the intermittent tributary. The maximum concentration was found downstream of the lye vat where the old floor drainage system discharged. Fe was detected in the limited on-site (0.001 mg/m3) and downwind (0.002 mg/m3) air samples taken during the initial remedial investigation. During the SRI the concentration of Fe in on-site air was 0.004 mg/m3. Inhalation of Fe can lead to harmless deposits in the lungs. The maximum concentration of Fe in the background off-site sample was 15,100 mg/kg. ATSDR has not developed MRLs and EPA does not have a RfD for Fe. Generally Fe excess does not occur from normal routes of exposure because the absorption of Fe is regulated according to need. Although Fe is an essential trace element, it can be harmful if taken in excess. The exact mechanism of Fe toxicity is not known, but it may shut down cellular metabolism by competing for electrons with the normal Fe-containing electron transport proteins in the mitochondria of the cells. Since the most likely route of exposure to the Fe is via dermal contact ATSDR believes that no adverse non-carcinogenic health effect would occur due to this exposure.

Studies regarding cancer from exposure to Fe in non-occupational settings were not found. Populations unusually susceptible to Fe toxicity were not found.

Lead (27)

Lead (Pb) is a naturally occurring bluish-gray metal. It has no special taste or smell and can be found in all parts of the environment. Most of the Pb comes from human activities like mining, manufacturing, and the burning of fossil fuels. Pb has many different uses, most importantly in the production of batteries. Pb is also in ammunition, metal products (pipes and solder), roofing, and devices to shield x-rays. Because of health concerns, Pb from gasoline, pipe solder, caulking, paints, and ceramics has been drastically reduced in recent years.

Foods such as fruits, grains, meat, seafood, soft drinks, vegetables and wine may contain Pb. Cigarettes also contain small amounts of lead. More than 99% of all drinking water contains less than 0.005 mg/l Pb. However, the amount of Pb taken into the body through drinking water can be higher in communities with acidic water supplies. Children residing in older dwellings may be exposed to Pb by eating lead-based paint chips from peeling surfaces. This is particularly a problem in lower income communities. For occupationally exposed individuals the usual route of exposure is through the inhalation of Pb particles.

Pb was detected in soil (90.3-2020 mg/kg), and sediment (8.7-569 mg/kg). The maximum concentrations were found in the off-site background soil samples, composited soil from the rail tie dump area, and in the sediments of the intermittent tributary downstream of where the old floor drainage system discharged. Blood Pb levels were not measured in any of the adults or children who lived or played around the site. ATSDR has no MRL and EPA has no RfD for Pb. The estimated exposure doses for each target population is below the LOAEL for neurological effects in monkeys (0.05 mg/kg/day). Ingestion of Pb at very high levels in soil may, over time, result in neurological impairment such as learning disabilities, especially in children. Although the most likely impacted population are children who played in the area of the rail tie piles dump (this exposure would have been infrequent since the contaminated soil is on-site and in the vicinity of the Washington-Douglas Elementary School, and not in the children's yards) and current on-site workers, ATSDR is unable to determine whether health effects were/are likely due to lack of biological data.

When released to the air from industry or burning of fossil fuels or waste, Pb tends to stay in the air for about ten days. Pb was not detected in air samples taken during the remedial investigation. It was noted in the toxicological profile for Pb that no studies were found describing adverse health effects in humans resulting from dermal exposure to inorganic Pb.

Pb is classified by EPA as a Class B2 probable human carcinogen based on animal studies. This means that there is inadequate evidence to determine Pb's carcinogenicity in humans. The estimated exposure dose is almost 100,000 times lower than the CEL in animals.

Pb exposure is particularly hazardous for unborn children and young children because they are more sensitive to it during their development. The American Academy of Pediatrics considers Pb a significant hazard to the health of children in the United States. The blood lead levels defining lead poisoning have been declining. Currently the consensus level of concern for children is 10 to 14 micrograms per deciliter (µg/dL). Effects on stature have been reported to begin at levels as low as 4 µg/dL, the present limit for accurate blood lead measurement. Taken together, effects occur over a wide range of blood lead concentrations, with no indications of a threshold. No safe level has yet been found for children. Even in adults, effects are being discovered at lower and lower levels as more sensitive analyses and measurements are developed.

Manganese (28)

Manganese is a silver-colored metal in its pure form and is found as a natural constituent in many types of rock. The metal form does not occur naturally in the environment. Manganese in nature occurs combined with other chemicals such as chlorine, oxygen, and sulfur. The metal manganese is mixed with iron to make steel. Some manganese compounds are used in the production of batteries, as an ingredient in some ceramics, pesticides, and fertilizers, and in dietary supplements.

Level of manganese in drinking water is usually about 0.004 mg/l, in soils the levels usually range from 40 to 900 mg/kg. For nearly all people, food is the main source of manganese, and usual daily intakes range from about 2,000 to 9,000 micrograms per day. The exact amount consumed depends upon the diet.

Manganese was found in the on-site surface water and sediments of the intermittent stream at maximum concentrations of 2.01 mg/l and 9290 mg/kg, respectively. The maximum concentrations in the off-site surface water and sediments of Jones Creek and the soils on the terrace above the site, were 0.389 mg/l, 1120 mg/kg, and 760 mg/kg, respectively. The estimated exposure doses are lower than the LOAEL for less serious effect in humans (0.059 mg/kg/day). Dermal absorption of manganese does not appear to be toxicologically significant. Limited air sampling during the RI and SRI indicate that manganese is not at levels of public health concern. No studies were found regarding carcinogenic effects in humans following exposure to manganese via ingestion, inhalation, or dermal absorption. ATSDR does not expect any adverse non-carcinogenic or carcinogenic health effects in people exposed to the manganese.

Neonates tend to retain a higher amount of manganese in their bodies than adults. Very high level of retained manganese can lead to neurotoxicity. Other susceptible populations include the elderly, people with liver disease, and people with respiratory disease. Smokers are more susceptible to development of respiratory symptoms (wheezing, bronchitis) from inhalation of manganese dusts than non-smokers.

Mercury (29)

Mercury is a naturally occurring metal which has several forms. The metallic mercury is a shiny, silver-white, odorless liquid. If heated, it is a colorless, odorless gas. Mercury combines with other elements to form salts, most of which are white powders or crystals. Mercury combined with carbon forms organic mercury. The most common organic mercury is methylmercury.

Metallic mercury is used to produce chlorine gas and caustic soda (lye) and also in thermometers, dental fillings, and batteries. Mercury salts are used in skin-lightening creams and in antiseptic creams and ointments.

Mercury was detected in on-site sediments at low concentrations. It was also detected in on-site ambient air at a maximum concentration of 0.0003 mg/m3. Most of the data on inhalation exposure to mercury comes from occupational case studies. The LOAEL for less serious effects in humans is 0.014 mg/m3, this concentration is orders of magnitude greater than the concentration detected in the ambient air on-site. ATSDR does not expect any adverse non-carcinogenic health effects to occur.

The Department of Health and Human Services, the Environmental Protection Agency, and the International Agency for Research on Cancer, have not classified mercury as to its human carcinogenicity because of a lack of data from studies on people and laboratory animals. There is no evidence from epidemiological studies to indicate that inhalation of inorganic (metallic) mercury produces cancer in humans. No studies were located regarding cancer in animals following inhalation exposure to metallic mercury. No studies were found regarding cancer in humans following oral or dermal exposure to inorganic mercury.

Nickel (30)

Nickel is a natural element in the earth's crust; therefore, people are constantly exposed to small amounts in food, water, and soil, and even smaller amounts in air. The daily intake of nickel from drinking water is about 2 µg. A person usually consumes 170 µg/day in his food. We breathe between 0.1 and 1 µg/day, excluding nickel in tobacco smoke. The National Academy of Sciences does not consider nickel to be an essential element for humans. Nickel-deficiency in humans has not been reported in the literature; however, it has been induced in several species of animals. Dermal contact with nickel usually occurs by contact with metals containing nickel or nickel-plated jewelry. Stainless steel and coins contain nickel. The form of nickel to which a person is exposed is often unknown. Much of the nickel found in sediments, soils, and rock is so strongly attached to dust and dirt or embedded in minerals that it is not readily taken up by plants and animals and cannot easily effect someone's health. People who are not sensitive to nickel must eat very large amounts in order to suffer adverse health effects. ATSDR does not know the forms of nickel found at this site.

During the SRI nickel was detected in on-site ambient air at a maximum concentration of 0.0002 mg/m3. This concentration is much lower than the concentrations found to cause adverse health effects in workers exposed to nickel in air for extended periods of time. ATSDR does not expect any non-carcinogenic adverse health effects in persons exposed to nickel in ambient air at the maximum concentration detected.

The Department of Health and Human Services has determined that nickel and certain nickel compounds may be reasonably anticipated to be carcinogenic. The ability of some nickel compounds to cause nasal and lung cancers when inhaled have been well documented in workers following chronic exposure. These adverse health effects occurred following long-term exposure to nickel (in a water soluble form) in air at concentrations greater than 1 mg/m3. Animal studies support these findings. No studies were located regarding carcinogenic effects in humans after oral exposure to nickel at low concentrations. Studies using animals exposed to nickel in drinking water did not show a significant increase in cancer risk. No studies were located regarding cancer in humans or animals after dermal exposure to nickel. ATSDR does not expect carcinogenic health effects to occur in people exposed to nickel at the maximum concentration detected on-site.

People who are sensitized to nickel may be unusually susceptible, because exposure to nickel in any form may trigger an allergic response. Black people tend to be more sensitive to nickel than White people and women of either racial group tend to be more susceptible than men. Since nickel is primarily excreted in the urine, individuals with kidney dysfunction are likely to be more sensitive to nickel. Diabetics are also likely to be more sensitive because of the hyperglycemic effects of nickel and because diabetics often have kidney damage.

Phosphorous (16)

Phosphorous comprises 0.12% of the earth's crust and is found in all fertile soil. It is found in the environment in the form of phosphates. Phosphorous comes in many colors (black, white, red, and yellow) depending upon the impurities within it. It is has a garlic-like odor and is used in the manufacture of many products including fireworks, incendiary shells, fertilizers, steel, and glass.

Phosphorous was detected in upwind ambient air samples taken during the RI at a maximum concentration of 0.002 mg/m3. ATSDR has no MRLs and EPA has no RfDs for this element. ATSDR has not developed a toxicological profile for phosphorous. Based upon literature reviewed, adverse non-carcinogenic health effects are not expected to occur in people breathing the air at the maximum concentration detected.

Phosphorous is not classifiable as to carcinogenicity due to lack of human and animal data.

Toxicological Evaluation Summary

Adverse non-carcinogenic health effects from exposure to copper at the ICG Iselin Railroad Yard National Priorities List site would have been minimal, if any. Due to lack of biological data, ATSDR could not determine if adverse health effects were likely to have occurred due to exposure to lead at the site. Adverse non-carcinogenic health effects are not expected from exposure to the other contaminants via incidental ingestion. Due to limited air sampling it is currently not known, with certainty, if any of the contaminants of concern in the contaminated soil, surface water, and sediments pose a threat via inhalation exposure.

Carcinogenic health effects are not expected to occur due to exposure to tetrachloroethene, polycyclic aromatic hydrocarbons, dieldrin, arsenic, cadmium, chromium, and nickel. It is not known if exposure to 2-hexanone, 2-methylnaphthalene, 4-methyl-2-pentanone, carbazole, dibenzofuran, aluminum, copper, phosphorous, and lead causes cancer in humans. Naphthalene is not classifiable as to its carcinogenicity in humans.

Based upon the data reviewed, exposure to the contaminated on-site surface soil would cause minimal adverse health effects, if any. However, direct contact should be avoided (especially in the area of the rail tie pile dump).

B. Health Outcome Data Evaluation

ATSDR conducts a review of health outcome data when the toxicologic evaluation indicates the likelihood of adverse health outcomes or when the community near the site has health concerns. The evaluation of health outcome data may give a general picture of the health of a community, or it may confirm the presence of excess disease or illness in a community. However, elevated rates of a particular disease may not necessarily be caused by hazardous substances in the environment. Other factors, such as personal habits, socioeconomic status, and occupation, also may influence the development of disease. In contrast, even if elevated rates of disease are not found, a contaminant may still have caused illness or disease.

The population surrounding the site is relatively small. Because the Wonder database provides information only to the county level it would not be specific enough to provide any meaningful information on the population potentially affected by the ICG Iselin Railroad Yard site. In addition, due to cessation of the railyard operations, it would be difficult to identify the affected or potentially affected former railyard population.

In June 1994, the Division of Environmental Epidemiology, Tennessee Department of Health reviewed cancer incidence data for the years 1988-1991. Cases reported to the Tennessee Cancer Reporting System for zip code 38301 (the zip code surrounding the site) were compared to cases reported for other Jackson zip codes. The data showed a significantly higher rate of all cancers, stomach and small intestine cancers, and kidney cancer in the populations in the 38301 zip code as compared to the populations in the rest of the Jackson zip codes. The increased rate of all cancers and stomach and small intestine cancer was driven by cases in persons aged 45 to 64. The increased rate of kidney cancer was driven by persons aged 65 and older. ATSDR does not have the information necessary to determine whether or not the increased cases of cancer are due to exposures to or releases from the ICG Iselin Railroad Yard site. The data also showed a significantly lower rate of non-Hodgkin's lymphoma in the 38301 populates as compared to the population in other Jackson zip codes.

ATSDR does not have any information regarding health complaints in current on-site workers (employees of Williams Steel).

C. Community Health Concerns Evaluation

  1. Can contaminants found at the site cause rashes, cancer, and stomach ailments?
  2. Some of the contaminants found on and near the ICG Iselin Railroad Yard National Priorities List site have the potential to cause rashes and stomach ailments. However, based upon the information reviewed by ATSDR and the proposed exposure scenarios, exposure to site-related contaminants in the contaminated media should not cause rashes or stomach ailments under normal circumstances.

    In the absence of hospital records and other medical history, it is difficult to determine whether or not any health problems could have occurred or will occur in persons exposed to the contaminants at the site. The manifestation of an adverse noncarcinogenic and carcinogenic health effect would also be determined by other factors in addition to exposure. These other factors include life style, nutritional status, sex, age, family traits, and state of health.

    Please refer to the discussions in the Toxicological Evaluation Summary and Health Outcome Data Evaluation subsections of the Public Health Implications section of this document for further information.

  3. My children played on the site when they were younger. What possible health effects can occur in my children in the future?
  4. Based upon information reviewed by ATSDR and the proposed exposure scenarios, it is unlikely that adverse health effects would occur in your children in the future (especially if they are no longer exposed to the site-related contaminants). However, given the concentration of lead in the on-site soils, it is recommended that the blood lead level for children playing on the site be screened to ensure that it is not above the Centers for Disease Control and Prevention's action level of 10 micrograms per deciliter. High levels of lead in the blood suggest that adverse effects may occur. If the blood lead level is high, intervention may be needed to lower the level.

    Lead bioaccumulates in the body and could cause problems in the future. Unborn children can be exposed to lead through their mothers. This may cause premature births, smaller babies, and decreased mental ability in the infant. Lead exposure may also decrease the intelligence quotient (IQ) scores and reduce the growth of young children. The effects of lead are the same regardless of whether it enters the body through inhalation or ingestion.

  5. Will ATSDR provide or recommend medical services to myself and the community?
  6. ATSDR does not provide medical treatment. At this time, ATSDR recommends that community members who feel that they may have been adversely affected by contaminants present at the site consult a physician experienced in diagnosing illnesses attributable to environmental factors. The Vanderbilt Poison and Clinical Toxicology Center in Nashville, TN may be able to assist. Call 1-615-936-0760 for more information. There is a charge for their services.



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