PUBLIC HEALTH ASSESSMENT
T.H. AGRICULTURE AND NUTRITION/MONTGOMERY PLANT SITE
MONTGOMERY, MONTGOMERY COUNTY, ALABAMA
ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
The following section is a review of the environmental data collected at the THAN site, and within a one and one-half mile radius of the site. The quality of the data will be assessed in this section, also. We will review the frequency of the contaminants of concern, their concentrations in various media, and the source of the contaminants. On-site contamination will be reviewed first, followed by off-site contamination. On-site is considered to be the 16.4 acres that comprises the THAN site, including the portion of the marsh located within this area. Off-site is the area outside the boundaries of the THAN site, but within a one and one-half mile radius.
The tables presented in Appendix B list the contaminants of concern in various on-site and off-site
media. The contaminants of concern are evaluated in later sections to determine whether
exposure has public health significance. The data tables and text include the following abbreviations:
| Cancer Risk Evaluation Guide | |
| Environmental Media Evaluation Guide | |
| Reference Dose Media Evaluation Guide | |
| Lifetime Health Advisory | |
| Maximum Contaminant Level | |
| Minimal Risk Levels | |
| parts per million/parts per billion | |
| Reference Dose | |
| Reference Dose Media Evaluation Guide | |
| Possible human carcinogen (no human, limited animal studies) | |
| Probable human carcinogen (inadequate human, sufficient animal studies) |
A review of the sampling data reported in the Remedial Investigation Report (RI) for THAN, the Supplemental Remedial Investigation Report (SRI) (26), and the Townsend Environmental Consulting data (14) found the following contaminants of concern (Note: * indicates that the contaminants are found off-site):
Selected Metals:
| Antimony * Barium * Cadmium * Manganese * Vanadium * |
Arsenic * Beryllium* Lead * Thallium |
Volatile Organic Compounds:
| 1,1,1-Trichloroethane 1,1-Dichloroethene * 1,2-Dichloroethene (Total) 4-Methyl-2-Pentanone Carbon Tetrachloride * Chloroform * Ethylbenzene Tetrachloroethene Xylene (Total) |
1,1-Dichloroethane 1,2-Dichloroethane 1,3-Dichlorobenzene Benzene Chlorine Dibromochloromethane Methylene Chloride * Trichloroethene * |
Semi-Volatile Organic Compounds
| 2,4,6-Trichlorophenol 2-Methylnaphthalene 4-Nitrophenol Dibenzofuran Hexachlorobenzene Naphthalene |
2,4-Dimethylphenol 4-Methylphenol bis(2-Ethylhexyl)-phthalate Dimethyl phthalate Hexachlorobutadiene Phenathrene |
Pesticides:
| Aldrin alpha-Chlordane delta-BHC * 2,4'-DDE 4,4'-DDD 4,4'-DDT Endosulfan Sulfate * Endrin Aldehyde gamma-BHC * Heptachlor * Toxaphene |
alpha-Benzene hexachloride (BHC) * beta-BHC * 2,4'-DDD 2,4'-DDT 4,4'-DDE Dieldrin * Endrin Endrin Ketone gamma-Chlordane * Heptachlor Epoxide |
The bases for selection of these contaminants are as follows:
Including a chemical in the list of contaminants of concern does not mean that adverse health effects necessarily will result from exposure. Identification of all contaminants assures that each one will be included in the public health assessment to be evaluated further as to its health impact on the local population.
In preparing a public health assessment, contaminant concentrations in specific transport media are compared to established comparison values to select specific contaminants of concern for further study. No comparison values exist for some constituents, and the tables reflect this situation. The most commonly used comparison values are ATSDR's Environmental Media Evaluation Guides (EMEGs) and Cancer Risk Evaluation Guides (CREGs), although other values may be used as necessary. CREGs are estimated contaminant concentrations based on one excess cancer case per million persons exposed over a lifetime. CREGs are derived from USEPA cancer slope factors. An EMEG is the amount of a particular contaminant that can be present in a specific medium below which no known non-cancer effects are expected to result from exposure. EMEGs are derived from ATSDR's Minimal Risk Levels (MRLs). A MRL is an estimate of daily human exposure to a contaminant below which non-cancer, adverse health effects are unlikely to occur.
When EMEGs and CREGs are not available, RMEGs are used. An RMEG is the estimated intake of a media-specific contaminant below which no known non-cancerous health effects are likely to occur. An RMEG is calculated from the USEPA RfD. The RfD is the daily acceptable intake level at or below which no non-cancerous health effects are expected from exposure.
ADPH did a search of the USEPA Toxic Chemical Release Inventory (TRI) for information on non-point and point releases on the THAN site and other industries in the area. This was done to insure that all contaminants and contaminant sources in the area were identified. The search area included the THAN site and all businesses located within the zip code area in which the site is located. The TRI showed no non-point or point releases occurred from 1987-1992 on the THAN site or at any other business in the surrounding area.
On-Site Groundwater
Results were obtained from 68 wells near the THAN site; 22 wells on-site and 46 wells off-site (Figures 3 & 7, Appendix A). Well depths were defined as shallow (30-35 feet), intermediate (48-69 feet) or deep (more than 80 feet). Forty-nine shallow wells were screened in the Alluvial/Terrace aquifer, and 13 intermediate wells were screened at the aquifer base. Four deep wells were screened in the permeable zones in the Middle Eutaw confining unit, and one deep well was screened at the top of the Lower Eutaw aquifer. One municipal well from the Montgomery West Well Field was sampled, also. Sampling results from the 68 wells are included in the RI and the Townsend Environmental Consulting data for the THAN site.
The on-site groundwater contained measurable amounts of 34 different contaminants of concern (Table 1, Appendix B). Metals were found in concentrations above background levels or above ATSDR's comparison values in both shallow and intermediate wells. Lead was retained in the table because it is a probable carcinogen. Vanadium was kept because it does not have a comparison value. VOCs and pesticides were most frequently found in high concentrations in the shallow wells in the Alluvial/Terrace aquifer. Most VOCs were above the CREG values. Ethylbenzene and 1,2-dichloroethene (Total) were reserved because they were above the RMEG values. The only VOC which was above the LTHA was 1,1,1-trichloroethane. Most SVOCs were retained because they did not have a comparison value. Only the exception to this was the SVOC naphthalene, which was above the LTHA. Nearly all pesticides were above the CREG values.
On-Site Surface Water
During August 1991 and November 1991, 39 surface water samples were taken at randomly selected locations on- and off-site (Figure 4, Appendix A). Surface water in the on-site marsh was sampled at three different locations. Samples were analyzed for selected metals, VOCs, semivolatile organic compounds (SVOCs) and pesticides. Maximum concentrations of contaminants of concern in on-site surface water are presented in Table 2 (Appendix B).
The main contaminants of concern in on-site surface water were metals. Metals found with concentrations above ATSDR comparison values were arsenic, barium, beryllium, manganese and thallium. Vanadium was kept because it does not have a comparison value, and lead was listed in Table 2 because it is a probable carcinogen. The SVOC 4-methylphenol (or p-cresol), and the pesticide 4',4'-DDD were the only non-metal contaminants of concern. DDD had concentrations above the CREG value, while 4-methylphenol was retained as a contaminant of concern because it is a possible carcinogen.
On-Site Shallow Soils
Five hundred seventy-five soil samples were taken from 156 locations on and around the THAN site (Figure 5, Appendix A). Twenty samples were taken from five other off-site locations and used as background samples. Several background samples were tainted with low amounts of VOCs.
We defined soils from zero to six inches as shallow soils. No samples were taken from the zero to three inch depth, defined by ATSDR as surface soils. ATSDR prefers to use surface soils because humans are most likely to come in contact with them. Table 3 (Appendix B) shows the maximum concentrations for the contaminants of concern found in the shallow soils. Shallow soil on the THAN site contained measurable amounts of 26 different contaminants of concern. Metals were found in concentrations above background levels or above ATSDR's comparison values. Lead was retained in the table because it is a probable carcinogen. Thallium was kept because it does not have a comparison value. The VOC, 4-methyl-2-pentanone, was retained in the table because there is no comparison value for this compound. The SVOCs were found to be above the CREG values, or they did not have comparison values. Most pesticides found in on-site soils were above the CREG values.
On-Site Sediments
Sediment samples were taken from two different areas on the THAN site (Figure 6, Appendix A). Thirteen samples were taken from the on-site marsh on the THAN property and five samples were taken from the storm sewer system that services the IC property. No sediment samples were taken from the IC property because there were no sediments present at the time of sampling. The IC storm sewer is located on-site and receives sediment derived from on-site soils. However, the IC storm sewer discharges off-site into the east ditch. Therefore, each sampling area will be addressed separately in this section.
Table 4 (Appendix B) shows the maximum concentrations for the contaminants of concern found in the sediment from the on-site marsh. Measurable amounts of nine different contaminants of concern were found in the on-site marsh sediment. Most metals had concentrations that were above ATSDR's comparison values. The only exceptions were lead and vanadium. Lead was retained in the table because it is a probable carcinogen, and vanadium has no comparison value. All pesticides found in on-site sediment had concentrations that were above the CREG values.
Maximum concentrations for contaminants of concern from the storm sewer system are listed in Table 5 (Appendix B). Measurable quantities of 26 different contaminants of concern were found in the sewer system sediment. With the exception of lead, all metals detected had concentrations above ATSDR's comparison values. The only VOC detected was 1,3-dichlorobenzene, and it was reserved because it has no comparison value. No comparison values exist for most of the SVOCs. The exceptions were hexachlorobenzene and hexachlorobutadiene which were above the CREG values. Eight pesticides had concentrations above CREG values, and two more were above EMEG values.
On-Site Data Gaps
There are no on-site data gaps for the THAN site.
Off-Site Groundwater
Forty-six off-site wells were tested in the area of the THAN site; 34 monitoring wells, one well in the City of Montgomery West Well Field, and eleven domestic wells (Figures 3 & 7, Appendix A). Of the 34 monitoring wells, six were used for background sampling. It should be noted that several of the background wells were contaminated with small amounts of VOCs and pesticides.
Table 6 (Appendix B) shows the maximum concentrations for the contaminants of concern found in the off-site wells. The off-site groundwater contained measurable amounts of 23 different contaminants of concern. Most metal concentrations were above ATSDR's comparison values. Exceptions to this were lead and vanadium. Lead was retained because it is a probable carcinogen, and vanadium was kept because it has no comparison value. Most VOCs found were above the CREG values. The VOC 1,1-dichloroethane was reserved because it is a probable carcinogen. Dibromochloromethane and 4-methyl-2-pentanone were kept in the table because they do not have comparison values. Most pesticides found were above ATSDR CREG values.
Some VOCs were detected in off-site groundwater that were not produced by the THAN site. These contaminants and their possible sources of contamination will be discussed in the off-site groundwater pathways section.
Off-Site Surface Water
Off-site surface water was sampled from the off-site marsh, the east ditch, the west ditch, and the ponds on the Twin Lakes property. Also, samples were taken from the drainage ditch that originates at the west ditch behind the THAN property and runs southwest. Sample locations are shown in Figure 4 (Appendix A). Maximum concentrations of contaminants of concern in on-site surface water are presented in Table 7 (Appendix B).
Measurable quantities of 25 different contaminants of concern were found in off-site surface water. The selected metals that were above ATSDR comparison values were arsenic, beryllium, cadmium, manganese, and thallium. Lead was retained in the table because it is a probable carcinogen. Vanadium was reserved because it has no comparison value. The only VOC in off-site surface water above the CREG value was benzene. Most pesticides exceeded the CREG values. No comparison values were available for delta-BHC, endosulfan sulfate, endrin ketone, and endrin aldehyde.
Surface water samples from the Twin Lakes ponds was analyzed for metals, VOCs, SVOCs, pesticides, and herbicides. Metals detected were below the comparison value or within background levels. The only contaminant found was carbon disulfide, a VOC. However, the amount of carbon disulfide did not exceed any of ATSDR's comparison values. No pesticides and herbicides were detected.
Off-Site Shallow Soils
Samples from shallow soils were taken from 26 locations in close proximity to the THAN site (Figure 5, Appendix A). Measurable amounts of ten different contaminants of concern were found in these samples (Table 8, Appendix B). Most metals were found in concentrations above background levels or above ATSDR's comparison values. Lead was the only metal which did not have a comparison value. It was retained because it is a probable carcinogen. Most pesticides found in off-site soils did not have a comparison value. The two isomers of chlordane that were found were above the CREG values. Isomers are two or more substances with the same chemical composition, but with different properties resulting from differences in atomic arrangement. No VOCs or SVOCs were detected at levels above ATSDR comparison values.
Off-Site Sediment
Off-site sediment samples were taken from the west ditch, east ditch, off-site marsh, and Twin Lakes area (Figure 6, Appendix A). Samples were taken from three transects in the west ditch and from five transects across the east ditch. The off-site marsh contamination was further delineated by supplemental sampling along the drainage area behind the site (Figure 8, Appendix A). Samples were taken from the drainage ditch in four different areas. Only the area directly behind the THAN site contained contaminants of concern that were above ATSDR's comparison values.
Measurable amounts of 20 different contaminants of concern were found in off-site sediment samples. Table 9 (Appendix B) shows the maximum concentrations for these contaminants. Metals were found in concentrations above background levels or above ATSDR's comparison values. Lead was reserved in the table because it is a probable carcinogen. Most pesticides found in off-site sediment were above CREG or EMEG values. The exceptions to this are the 2,4'- isomers of DDT, endosulfan sulfate and delta-BHC. These pesticides have no comparison values.
Sediment samples from the Twin Lakes area were analyzed for metals, VOCs, SVOCs, pesticides, and herbicides. All metals detected in the Twin Lakes area were within the range for background samples. The only contaminant found was benzene. However, the amount of benzene did not exceed any of ATSDR'S comparison values. No pesticides, herbicides or SVOCs were detected.
Off-Site Data Gaps
There is inadequate data to characterize the extent of the northwest-trending plume in the intermediate wells. More wells should be placed in the Twin Lakes community to better assess this plume. Also, there is insufficient data to locate the possible source or sources for the VOCs which are not related to the site.
C. Quality Assurance and Quality Control
A Quality Assurance/Quality Control (QA/QC) summary for the THAN site was provided to ADPH by the USEPA. Sampling and analyses procedures were reported in the Remedial Investigation Report. According to Alan Yarbrough, USEPA's Remedial Project Manager for the THAN site (15), the field data, sampling procedures and laboratory analyses met USEPA requirements. Therefore, in compiling this report, we assumed that adequate QA/QC controls have been followed. The accuracy and completeness of this report are dependent on the adequacy and reliability of the results presented in the previous site reports.
Groundwater data collected by the Townsend Environmental Consulting was reviewed by the report preparers to assess its validity. Boring logs were reviewed and deemed acceptable. Samples analyzed according to "Methods for Organic Chemical Analysis of Municipal and Industrial Wastewater" (EPA-600/4-82) Method 608/625. Selected samples were split and sent to two different laboratories to insure that the analytical results were not biased. The results from each laboratory were within acceptable limits, and thus, are treated as valid.
Several discrepancies have been noted in the Remedial Investigation Report. Reported values for 2,3,7,8-TCDD, Total TCDD, 2,3,7,8-TCDF and Total TCDF given in Table 11-5 are incorrect. The table should show values for contaminants of concern in the storm sewer sediments that are listed in Table 9-10 (25). These inconsistences have been noted by the potential responsible parties, and will be corrected in future documents.
When evaluating the adequacy of the data in the sections on-site and off-site contamination, we assumed that estimated (J) values are valid. We used estimated values in the tables listing contaminants of concern in the various media when they exceeded all other reported values for a contaminant in the media under consideration.
Caution should be used in evaluation of soil and groundwater data. Several background soil and groundwater samples were contaminated with small amounts of VOCs and pesticides. The groundwater samples were taken during the rainy season and may be a biased sampling for two reasons: 1) The samples that were taken may have higher contaminant levels than normal because more contaminants may have been leached out of the soil by rainwater; 2) Dilution may have occurred and the contaminant levels may be lower than normal.
No physical hazards were noted during the site visit.
An evaluation of completed exposure pathways and potential exposure pathways was made to determine exposure to contaminants of concern by on-site workers and people living near the THAN site. Exposure pathways are made up of five elements: source of contamination, environmental media, point of exposure, route of human exposure and receptor population. Exposure pathways are classified as completed, potential or eliminated pathways. Completed pathways are those for which all five elements are present and human exposure to a contaminant or contaminants has occurred in the past or present, or is expected to occur in the future. When one or more of the elements are absent but could exist, then the pathway is characterized as a potential exposure pathway. When one or more elements are missing and never has been and never will be present, then that pathway is eliminated from further consideration. Only the pathways that are significant and relevant to the THAN site are discussed in detail.
A. Completed Exposure Pathways
East Ditch Sediment Pathway
Sediments in the east ditch area are a completed exposure pathway for CSX Transportation workers (Table 10, Appendix C). CSX Transportation workers become exposed by incidental ingestion of sediment particles as they work along the railroad spur. Exposure to high levels of contaminants may occur among Department of Transportation (DOT) workers, utility workers, telephone repairmen or trespassers who work on buried cable, set power poles, work on overhead lines, or walk along the east ditch. We have classified the sediment exposure pathway as a completed rather than potential pathway because CSX workers are being exposed or have been exposed to contaminants of concern in the east ditch, during regular maintenance and loading activities.
On-Site Shallow Soil
Although it has not been reported that actual exposures did occur, it is highly likely that workers on the THAN site were exposed to contaminants of concern in shallow soil (0 to 6 inches). Two pits have been found on the THAN site which suggest that the soil was disturbed. Workers were probably exposed by incidental inhalation and dermal contact with contaminants in shallow soil because past regulations for worker safety were less stringent. Also, a lack of knowledge that the contaminants were harmful to human health, and lenient disposal practices increased the workers chances of exposure. Therefore, we have classified the shallow soil as a past completed exposure pathway for workers on the THAN site (Table 10, Appendix C).
On-Site Shallow Soil Pathway
Exposure to shallow soil (0 to 6 inches) is a potential exposure pathway for present and future workers on the THAN site (Table 11, Appendix C). IC workers are the population most likely to be exposed through incidental inhalation, ingestion, or dermal contact because more barren soil areas are located on the IC property where direct exposure can occur. However, workers are warned that hazardous material is present in the soil and that precautionary measures should be taken. We have classified the shallow soil as a potential exposure pathway because workers may be exposed to contaminants of concern which are above ATSDR comparison values.
On-Site Groundwater Pathway
On-site wells pattern three different plumes of contaminants: (1) a north-trending plume in the shallow wells, (2) a northeast-trending plume in the shallow wells, and (3) a northwest-trending plume in the intermediate wells. Several different locations can be identified as on-site contaminant sources for the two plumes in the shallow aquifer (Figure 9, Appendix A). Source areas on the IC property are the drum wash zone, the former lagoon, and the former incinerator. Contaminant source areas on the THAN property are the former waste disposal area and the zone just north of the railroad spur near the THAN well. Most VOCs originate from the former disposal area, the drum wash zone, and the former incinerator. Source areas of pesticides tend to be more diverse. Isomers of benzene hexachloride (alpha, beta, gamma, delta-BHC), p,p'-dichlorodiphenyltrichloroethane (DDT, DDD, DDE), and endrin are found in high concentrations in samples taken near the drum wash area of the IC property. The pesticides dieldrin and endrin have been detected in the former lagoon area. DDT on the IC property is confined strictly to the former incinerator and drum wash area. High concentrations of BHC, DDD, DDE, dieldrin, and endrin are found in samples from the disposal area on the THAN property. Samples from the zone just north of the railroad spur near the THAN well contain BHC, DDE and dieldrin.
Contamination in the northwest-trending plume in the intermediate wells is limited to a few on-site source areas. Pesticides in the intermediate wells appear to originate from the same source areas as seen in the shallow wells. Most VOCs appear to be originating from the former disposal pit area on the THAN property. The exceptions are trichloroethene (TCE) and tetrachloroethene, which will be discussed in off-site groundwater.
No known on-site exposure to groundwater is occurring at present except for possible exposure to the workers who conduct groundwater sampling (Table 11, Appendix C). Workers wear protective equipment, making exposure unlikely. Currently, IC and Capitol City Insulators obtain potable water from the City of Montgomery. Thus, no exposure is currently occurring among workers on the THAN site.
On-Site Surface Water
It is doubtful that contact or ingestion of on-site surface water is, has been, or will be a significant exposure pathway (Table 11, Appendix C). Some metals and pesticides were found at levels above ATSDR comparison values; however ingestion of surface water will occur only in unusual and rare circumstances, and the amounts ingested would necessarily be small. No incidences of wading in the marsh have been reported, and the marsh is partly fenced to prevent unwanted trespassing. In the event that wading in the marsh does occur, the surface water pathway will need to be reassessed.
On-Site Ambient Air
Exposure to on-site ambient air may have occurred in the past. Workers from the THAN site report that they were exposed to chlorine gas, yet it is unknown whether they were wearing the proper safety equipment. It is possible that exposure may have occurred because regulations regarding worker safety were less stringent. However, an analysis of existing databases does not show that a chlorine release occurred at the THAN site in the past.
Off-Site Sediment
It is unlikely that exposure to sediments found in the west ditch and in the drainage ditch directly behind the THAN site are, have been, or will occur. Some metals and pesticides were found at levels above ATSDR comparison values; however, these areas have dense vegetation which provides limited access. A sewage line is located near the west ditch which does present the possibility that an individual may enter this area. Also, these areas are not fenced off. Therefore, we have categorized exposure to off-site sediments as a potential exposure pathway.
Off-Site Shallow Soil
It is unlikely that exposure to off-site shallow soil has or will occur in the past, present, or future. Off-site shallow soils found in close proximity to the northern, western, and southern boundaries of the THAN site do contain some contaminants of concern at levels above ATSDR comparison values. However, passage to the contaminated soils is very limited due to thick foliage. As previously mentioned, a sewage line is situated in the area of the west ditch which does present the likelihood that individuals may enter this region. Thus, we have classified exposure to off-site shallow soil as potential.
Off-site Groundwater Pathway
Off-site wells located in the vicinity of the THAN site further characterize the three different plumes mentioned previously. Based on the isoconcentration maps of total BHC and the total pesticides in groundwater, the two plumes in the shallow aquifer appear to extend about 2900 feet in a north and northeast direction, beginning in the southwest corner of the THAN site (Figure 10, Appendix A). The southern edge of the northeastern plume extends approximately 220 feet south of the site. The western edge of the northern plume extends approximately 265 feet west of the site. The extent of northwest-trending plume in the intermediate wells cannot be determined from the existing database, and therefore is not shown in Figure 10.
As previously noted, most VOCs appear to be originating from the former disposal pit on the THAN property, with the possible exception of TCE and tetrachloroethene. The majority of TCE appears to originate from the former disposal pit; however, small amounts of TCE were found in upgradient wells east-southeast of the THAN site. These detections of TCE do not appear to be related to the THAN site because no TCE has been found in intermediate wells directly west. Tetrachloroethene in concentrations of around 50 ppb has been found in upgradient off-site wells south and east of the site. This suggests that an off-site source is contributing to the tetrachloroethene found in the off-site groundwater.
One deep well located near the southeast corner of the site showed levels of VOCs above ATSDR's comparison values. Well MW-13D contained trichloroethene and benzene. This well extends to a depth of approximately 142 feet. This places the bottom of the well near the top of the Lower Eutaw, one of the aquifers from which the City of Montgomery draws water. The well was resampled during Phase II and did not disclose any contaminants of concern. However, Phase II was conducted during the rainy season and samples may have been diluted. Therefore, it is impossible to determine at this time the nature and extent of the contamination in the Lower Eutaw. The single well that was sampled from the City of Montgomery West Well Field is located in the Eutaw Formation, but it contained no contaminants of concern.
No present exposure to contaminated groundwater is known to exist because most of the residences within a two-mile radius of the site are connected to the municipal water supply. Possible exposure may occur at nearby businesses who use private wells for industrial purposes. We have no reported incidences of past exposures. The two plumes in the shallow aquifer currently extend about 2900 feet from the southwest corner of the site. The extent of the plume at intermediate well depth has not been determined. However, taking into account the speed of the groundwater flow in the Alluvial/Terrace aquifer (30 feet per year) and the rate of dispersion for the contaminants, it is unlikely that site contaminants would have reached domestic wells because the spatial extent of the plumes would have been less in the past. Future exposure is possible because there are no restrictions on domestic well use in the area, and contaminants have migrated off-site in the shallow aquifer (Table 11, Appendix C).
Off-Site Surface Water
It is improbable that exposure to surface water from the off-site marsh, east ditch, or west ditch are or will be a notable pathway (Table 11, Appendix C). Some pesticides and metals were found at levels above ATSDR comparison values. One volatile was found at a level equaling ATSDRs comparison value. Although no playing or wading in these areas have been reported, the potential for individuals to enter these areas does exist because they are unfenced. If playing or wading in these areas does occur, this exposure pathway will need to be reevaluated.
On-Site Subsurface Soil Pathway
Contaminants in subsurface soils were found in concentrations above ATSDR comparison values. Exposure to subsurface soil is unlikely unless the soil is disturbed (Table 11, Appendix C). In the event of on-site soil disturbance, this medium may need to be reassessed.
Twin Lakes Sediment
Exposure to sediment from the Twin Lakes community has been eliminated as an exposure pathway. No pesticides, herbicides or SVOCs were detected in the sediment. All metals detected in the Twin Lakes community were within the range for background samples. The only contaminant found was benzene. However, the amount of benzene did not exceed any of ATSDRs comparison values. Therefore, we eliminated the sediment pathway.
Twin Lakes Ponds
Exposure to surface water from the Twin Lakes ponds has been eliminated from consideration as an exposure pathway. No pesticides, herbicides, and SVOCs were detected. Carbon disulfide, a VOC, was detected. However, the amount of carbon disulfide did not exceed any of ATSDRs comparison values. Carbon disulfide gas is normally found in marshy areas and should not be considered a contaminant. Metals detected were below ATSDR comparison values or within background levels. Therefore, we have eliminated the surface water pathway from further consideration.
Twin Lakes Shallow Soil
Shallow soil (0 to 6 inches) has not been sampled in the Twin Lakes community. However, sediment and surface water have been sampled. Contaminants of concern were not detected in these media, or were below ATSDR comparison values. Also, an ambient air pathway does not exist for contaminants to migrate off-site. Thus, we have eliminated the soil in the Twin Lakes community from further consideration because no pathway exists for contaminants to reach this media.
Ambient Air
The potential for exposure via ambient air has been eliminated from consideration because data show that a current air exposure pathway does not exist on-site or off-site. Therefore, we have eliminated ambient air as a current and future exposure pathway.
Municipal Water Supply
Current data show that the water that is supplied to the City of Montgomery by the West Well Field has not been affected by contaminants from the THAN site. Since the contaminant plume would be more widespread now than it was in the past, it is implausible that exposure via the municipal water supply has been, or will be a significant pathway (Table 11, Appendix C).
Biota
According to an official at the National Oceanic and Atmospheric Administration (NOAA), it is doubtful that exposure to wildlife is, has been or will be a significant pathway (27). Some animals may be using the marsh as a part of their habitat, and thus, become exposed to contaminants of concern. However, the amount of contamination that actually moves through the food chain would be small because most of the contaminants would be retained in the fatty tissue of the animals. Also, the amount of hunting and fishing that occurs is small because the surrounding area is within the City of Montgomery.
Groundwater contaminants do not appear to have caused adverse health effects to biota in the surrounding water bodies. Catoma Creek and its inhabitants have not been affected by contaminants from the THAN site in the past or present. However, it is not known whether contaminated groundwater has or is discharging into the West End Ditch (26).
Twin Lakes Fish
Fish in the Twin Lakes ponds have not been sampled, but sampling data is available for the sediments and surface waters from the ponds. No pesticides, herbicides, or SVOCs have been detected in either the surface water or the sediment. Some metals were found, but all were within background limits or below ATSDR comparison values. The only contaminant detected in the ponds is carbon disulfide, a VOC. Carbon disulfide gas normally is found in low quantities in marshy areas and is not considered to be a contaminant of concern. Since there is no pathway for contaminants to reach the fish, we have eliminated the pathway from further consideration.
This section will discuss the health effects of site contaminants on the people exposed, evaluate health outcome data, and address questions and concerns raised by the community members and site workers.
ATSDR has developed Minimal Risk Levels (MRLs) for contaminants commonly found at hazardous waste sites. MRLs were developed for ingestion and inhalation exposure routes, and take length of exposure into account. Length of exposure is divided into acute (less than 14 days of exposure), intermediate (15 to 364 days) and chronic (365 days or more).
If an MRL is not available for a specific contaminant, ATSDR uses the USEPA's Reference Dose (RfD). An RfD is an estimate of a lifetime daily human exposure to a contaminant, below which no non-cancer health effects are likely to occur.
We have made certain assumptions in calculating estimated exposure doses. The calculations are based on an adult with an assumed weight of 70 kilograms (kg) (154 pounds), who has a standard water ingestion rate of two liters per day. We assumed that adults ingest 100 milligrams of soil each day (mg/day) through inhalation of soil particles in the air, and from incidental ingestion of soil particles on hands placed in the mouth. For the purpose of this report, we used the maximum possible exposure duration of 47 years (1946-1993) for adults to obtain the most conservative estimate of risk. Dose estimates for CSX workers are based on an exposure of eight hours per day for five days per week for 47 years. The estimated risk to DOT workers, trespassers, utility workers, and telephone repairmen would be considerably less than the risk to CSX workers because they are exposed for shorter durations on an intermittent basis. However, these persons are at danger to acute exposures. No standards have been set to calculate risk of exposure to unborn children; therefore, no risk estimates were made.
Estimated doses and cancer risks are compared to health guidelines. If health guidelines are exceeded, the possibility that adverse health effects could occur does exist. However, the reader should bear in mind that these are only estimates do not mean that any adverse health effects have or will occur. Additional reports in the scientific literature are used to determine if adverse health effects are likely to result from exposure at the levels detected. Please refer to Appendix D to see the categories used to evaluate the potential cancer risks.
Only those contaminants found in completed exposure pathways above comparison levels, or for which no comparison values are available, will be discussed in this section. Each contaminant will be discussed in terms of the population affected, the routes of exposure, and acute or chronic health effects, if any, which may result from the exposure. Any increased risk of cancer to the exposed populations will be discussed.
Antimony (20)
Antimony is a silvery white metal found in the earth's crust. Antimony ores are mined, and then changed into antimony metal or combined with oxygen to form antimony oxide, a white powder. Antimony oxide does not evaporate, and does not dissolve easily in water. It is used primarily in textiles and plastics manufacturing to keep these products from burning.
Antimony metal is easily broken, and thus is rarely used by itself. Usually, it is mixed with other metals such a lead or zinc to form alloys, or mixtures, of metals. As an alloy, antimony is used in lead storage batteries, solder, sheet and pipe metal, ammunition and pewter.
Antimony enters the environment during the mining and processing of ores and in the production of alloys and compounds. Almost all antimony used in the United States is imported from other countries for processing. Some antimony is released to the environment by incinerators and coal-burning power plants. These antimony particles are very small and settle to the ground or are washed out of the air by rain. Antimony can attach to other small particles and remain in the air for more than a month. Most antimony will end up in soils or sediments, where it attaches strongly to iron-, manganese-, or aluminum-containing particles. Much of the antimony found in sediment, soil, and rock is so strongly attached to dust or dirt particles or buried in minerals that it usually cannot enter the body in a form that can cause health effects. Still, some antimony is less tightly attached to particles, and may be taken up by plants and animals.
Antimony enters the body through drinking water, eating food, soil, or other antimony- containing substances, or through breathing. Antimony that is swallowed enters the bloodstream within a few hours. Eating or drinking large doses can cause vomiting, which prevents most of it from being absorbed by the body. When breathed, antimony drawn into the lungs can enter the bloodstream after several days or weeks. After entering the blood, most antimony migrates to the liver, lungs, intestines, and spleen. During a period of several weeks after exposure, antimony will leave the body in feces and urine.
Antimony has not been classified for cancer effects by the USEPA or other major federal or international agencies. Antimony has been found in sediment in the east ditch. The estimated dose for an individual exposed to antimony at levels found in the east ditch sediment at the THAN site is much less than the USEPA's chronic oral Rfd. Therefore, we feel that exposure to antimony at the levels found at the THAN site is not likely to result in adverse health effects.
Arsenic (21)
Arsenic occurs naturally in the environment, usually in combination with other elements. When combined with oxygen, chlorine, and sulfur, it is called inorganic arsenic. Organic arsenic is arsenic combined with carbon and hydrogen. The organic forms are usually less harmful than the inorganic varieties. Most organic and inorganic forms are white or colorless powders with no smell or special taste.
Inorganic arsenic is poisonous. Long-term oral exposure to inorganic arsenic can lead to darkening of the skin and the development of small corn or wart-like growths on palms of hands, soles of feet, and torso. Occasionally, these growths may develop into skin cancer. Arsenic is classified by the USEPA as a human carcinogen. Oral intake of arsenic has been associated with increased risk of liver, bladder, kidney, lung, and skin cancer.
Arsenic was detected in east ditch sediments and on-site shallow soils at the THAN site. The estimated dosage to CSX Transportation workers who are exposed to sediment in the east ditch is sightly higher than ATSDR's chronic MRL. However, the MRL is set 1000 times below the level at which arsenic causes non-cancerous adverse health effects in animals. For workers exposed to arsenic at levels found in shallow soil on the THAN site, the estimated dosage for an individual is much less than ATSDR's chronic MRL. Therefore, we feel that no non-cancerous adverse health effects will result from exposure to arsenic in sediment in the east ditch and on-site shallow soil.
Railroad switchers and utility workers are exposed to arsenic in the east ditch. Workers on the THAN site are exposed to arsenic in on-site shallow soils, also. The estimated risks for cancer are low for workers who were exposed to arsenic at the levels found in the east ditch sediments and in on-site shallow soil for eight hours per day for five days per week for 47 years. Thus, we feel that exposure to arsenic at the levels found at the THAN site does pose a low threat for cancer.
Benzene hexachloride (BHC) (34)
Benzene hexachloride (BHC), now known as hexachlorocyclohexane, is a synthetic chemical that exists in eight chemical forms. Alpha, beta, delta, and gamma-BHC (or lindane) are some of these forms. When mixed together, these isomers produce what is called technical-grade BHC. Technical-grade BHC is no longer used as an insecticide in the U.S. and has not been produced in this country since 1983. However, lindane is still used as a pesticide.
BHC isomers can enter the air from contaminated soil and from plants grown in contaminated soil. Rainwater can leach BHC from soil into surface water and groundwater. Typically, people are not exposed to the alpha, beta, and delta forms of BHC separately, but rather to technical-grade BHC. Humans can be exposed to alpha, beta, and delta-BHC in workplace air, in the air surrounding manufacturing plants or agricultural fields, or by eating plants, meat, milk, or water that contain forms of BHC. In the past people were exposed to lindane when it was applied to skin as a lotion to control lice and scabies.
Alpha, beta, and delta-BHC have been detected in shallow soil on the THAN site. To get at total BHC exposure for the THAN site, the alpha, beta, and delta-BHC isomers were summed, and the total was used in risk analysis calculations. The estimated adult doses for THAN workers from on-site shallow soil are below than ATSDR's acute oral MRL. Therefore, we feel that no non-cancerous adverse health effects will result from exposure to BHC in shallow soil at the THAN site.
The Department of Health and Human Services has determined that BHC may cause liver cancer. Based on evidence from animal studies, the USEPA has classified BHC as a probable human carcinogen. This means that there is evidence from animal studies that it causes cancer, but the evidence is weaker or inadequate for humans. For workers exposed to BHC at the levels found in shallow soil on the THAN site for eight hours a day for five days a week for 47 years, the increased cancer risk is estimated to be low.
Beryllium (22)
Beryllium is a hard, grayish substance that occurs as a chemical component of some rocks, soils, and volcanic dust. Beryllium enters the environment because of natural processes and human activities. Most beryllium in sediment is bound to soil particles, thus movement deeper into the ground or into the groundwater is unlikely. Most adverse health effects from beryllium are caused by breathing the substance. However, air has been eliminated as a potential exposure pathway for the THAN site so no threat to human health is possible through air.
No adverse health effects are known to occur from ingestion exposure, and oral exposure has not been found to cause cancer in animals. For workers who ingested or were orally exposed to beryllium at the levels found in east ditch sediments and on-site shallow soil for eight hours per day for five days a week for 47 years, the increased cancer risks are estimated to be very low. Therefore, we feel that exposure to beryllium at the levels found at the THAN site is not likely to result in cancer.
Bis(2-ethylhexyl)phthalate (33)
Bis(2-ethylhexyl)phthalate is a man-made chemical used in the production of plastics. The compound is also called Di(2-ethylhexyl)phthalate or DEHP. DEHP is a colorless liquid that has virtually no odor. The compound is everywhere in the environment because of its use in plastics, but it evaporates into air and dissolves into water at very slow rates. DEHP strongly attaches to soil and is easily broken down into harmless compounds by small organisms in the soil and water.
Exposure to DEHP can occur through several routes. DEHP can enter the body by inhalation of air where DEHP is released, and by eating some foods packaged in plastics. The chemical also can enter the body through consumption of water containing the substance.
There is no evidence that DEHP causes serious health effects in humans. Most of what we know about the health effects of DEHP comes from adverse health effects in rats and mice. DEHP has been found in shallow soils on the THAN site. The estimated dose for an individual exposed to DEHP at levels found in shallow soil at the THAN site is much less than ATSDR's chronic oral MRL. Therefore, we feel that no non-cancerous adverse health effects will result from exposure to DEHP at the THAN site.
The USEPA has classified DEHP as a probable carcinogen. No epidemiologic evidence has linked exposure of DEHP to cancer in humans. However, several studies have shown that DEHP caused liver cancer in laboratory animals. For workers who were exposed to DEHP at the levels found in shallow soil on the THAN site for eight hours per day for five days a week for 47 years, the increased cancer risk for liver cancer is estimated to be very low. Therefore, the DEHP found at the THAN site is not judged to be a public health threat.
Chlordane (17)
Chlordane is a man-made chemical that has several isomers. Two of the isomers, alpha-chlordane and gamma-chlordane have been found at the THAN site. Alpha-chlordane and gamma-chlordane are breakdown products of chlordane. To estimate a total chlordane exposure, the amount of alpha-chlordane and gamma-chlordane were summed in each sample, and the total concentration was used in risk analysis calculations.
Chlordane was used in the United States as a pesticide from 1948 until 1988, when it was banned. From 1983 until 1988, it was approved for termite control, only. The USEPA banned chlordane because it persists in the environment and endangers humans and wildlife. Chlordane continues to be manufactured in the United States for export to foreign markets.
The highest exposure to chlordane comes from living in homes treated with chlordane for termites prior to 1988. The chemical may remain for years in indoor air following treatment. Digging around foundations of houses sprayed with chlordane can lead to exposure, also. In addition, exposure can occur through eating contaminated food because chlordane persists in the environment on previously treated farmland.
Chlordane has been found in sediment in the east ditch and in on-site shallow soils. The estimated dose for an individual exposed to chlordane at levels found in sediment in the east ditch is slightly higher than the USEPA's RfD. However, the RfD is set 1000 times below the level at which chlordane causes non-cancerous adverse health effects in animals. For workers exposed to chlordane in on-site shallow soil, the estimated dose is below the USEPA's RfD. Therefore, we feel that exposure to chlordane at the levels found in east ditch sediments and on-site shallow soil is unlikely to result in adverse health effects to workers.
Based on animal studies, the USEPA has classified chlordane as a probable human carcinogen because chlordane has been found to cause liver cancer in mice. For workers exposed to chlordane at the levels found in on-site shallow soil and east ditch sediments at the THAN site for eight hours a day for five days a week for 47 years, the increased cancer risks are estimated to be very low.
DDD, DDE, DDT (16)
DDT is a white, crystalline, tasteless and nearly odorless solid. Once it was a widely used chemical for controlling agricultural insects, disease-carrying insects, and other pests. DDT use is now prohibited in the United States except in cases of a public health emergency. The chemical does not occur naturally in the environment.
DDD and DDE are breakdown products of DDT. To get at total DDT exposure, the amount of DDT, DDD and DDE were summed(1), and the total was used in risk analysis calculations. The route of exposure to DDT and its breakdown products at the THAN site is through incidental ingestion and inhalation of soil. The estimated adult doses for DDT from east ditch sediments are higher than ATSDR's acute oral MRL. ATSDR has not derived a chronic MRL for DDT. Only MRLs for acute and intermediate duration effects have been derived.
The estimated dose for an individual exposed to DDT at levels found in east ditch sediments at the THAN site is six times as great as the acute oral MRL. Some adverse health effects associated with exposure to high levels of DDT are related to the central nervous system. Symptoms of nervous system disorders in humans are hyperexcitability, tremors and convulsions. Similar symptoms have been found in animal studies following acute and chronic exposures. Learning deficiencies have been found in adult mice exposed to DDT before birth. Other animal studies have found developmental and reproductive effects associated with DDT exposure.
The estimated adult doses for DDT from shallow soil on the THAN site are slightly higher than ATSDR's acute oral MRL. However, the MRL is set 1000 times below the level at which DDT causes adverse health effects in animals. Therefore, the DDT found in shallow soil on the THAN site should pose no significant threat to exposed workers.
DDT and its breakdown products may increase the risk of cancer in exposed populations. The USEPA has classified DDT as a probable human carcinogen. A probable human carcinogen is one for which there is good evidence of carcinogenesis based on animal studies, but for which the human evidence is weak or inadequate. Some studies show that liver and breast cancer are associated with DDT. For workers exposed to DDT at the levels found in east ditch sediments and on-site shallow soils for eight hours per day for five days a week for 47 years, the increased risks for cancer are estimated to be low.
Dieldrin/Aldrin (18)
Dieldrin and aldrin are two structurally similar compounds that were once used as insecticides. These compounds are discussed together because aldrin breaks down into dieldrin. The insecticides are produced in the laboratory and do not occur naturally in the environment. Aldrin and dieldrin evaporate slowly when exposed to air. These insecticides may be found near hazardous waste sites in soil, water, and air. Also, they may be found in plants and animals.
Aldrin and dieldrin were used extensively as insecticides on corn and cotton from 1954 until 1970 when the U.S. Department of Agriculture banned them for use on crops. The USEPA approved both insecticides for use in termite control in 1972. In 1987, the manufacturer voluntarily canceled the registration that allowed aldrin and dieldrin to be used for termite control.
Most human exposure to aldrin and dieldrin comes from eating contaminated foods, including fish or shellfish from contaminated waters, root crops, dairy product and meat. Dieldrin stays in the environment for a long time. Exposure can occur also through drinking water, breathing air, or touching soil contaminated with the chemicals. In homes treated for termites, inhabitants can breathe in the chemicals for several years after treatment.
Dieldrin has been found in sediments in the east ditch, and aldrin has been found in on-site shallow soils. The estimated dose for an individual exposed to dieldrin at levels found in the east ditch sediments is much less than ATSDR's chronic MRL. For workers who are exposed to aldrin at levels found in shallow soil on the THAN site, the estimated dose is slightly above ATSDR's chronic MRL. However, the MRL is set 1000 times below the level at which aldrin causes adverse health effects in animals. Therefore, we feel that there is no significant risk for non-cancerous adverse health effects for workers exposed to dieldrin and aldrin in east ditch sediments and on-site shallow soil.
The USEPA has classified dieldrin and aldrin as probable human carcinogens because the substances cause liver cancer in mice. For workers who were exposed to dieldrin at the levels found in the east ditch sediments for eight hours per day for five days a week for 47 years, we estimate that there is a very low increased risk for cancer. Therefore, we feel that dieldrin found at the THAN site is not a threat to human health. For workers who were exposed to aldrin at the levels found in shallow soil on the THAN site for eight hours per day for five days a week for 47 years, we estimate that there is a low increased risk for cancer.
Heptachlor epoxide (30)
Heptachlor epoxide is a white powder and is a breakdown product of heptachlor. Heptachlor is produced in the laboratory and is used as an insecticide. Heptachlor epoxide occurs naturally from the bacterial-breakdown of heptachlor. Also, Humans can produce heptachlor epoxide when heptachlor is introduced into their bodies. Heptachlor epoxide dissolves easily in water and strongly sticks to soil particles. The compound evaporates slowly to the air and can stay in them soil and water for many years.
Exposure to heptachlor epoxide may occur in several ways. Individuals may be exposed to heptachlor epoxide by eating crops grown in soil treated with heptachlor. Eating fish, dairy products, and fatty meats from animals exposed to heptachlor can be a route of exposure. Exposure also can occur by breathing air, drinking water, or from skin contact with contaminated soil near waste sites or landfills.
Heptachlor epoxide has been found in on-site shallow soils at the THAN site. The estimated dose for an individual exposed to heptachlor epoxide at levels found in shallow soil at the THAN site is much less than the USEPA's chronic oral RfD. Therefore, we feel that no non-cancerous adverse health effects will result from exposure to heptachlor epoxide at the THAN site.
Heptachlor epoxide is considered by the USEPA to be a probable human carcinogen because studies have shown that exposure to heptachlor epoxide has caused liver tumors in animals. For workers who were exposed to heptachlor epoxide at the levels found in shallow soil on the THAN site for eight hours per day for five days a week for 47 years, the increased cancer risk is estimated to be very low. Therefore, we feel that heptachlor epoxide found at the THAN site is not a threat to human health.
Hexachlorobenzene (31)
Hexachlorobenzene is a white, crystalline solid that is not naturally-occurring in the environment. The compound is formed as a by-product during the manufacture of other chemicals, including pesticides. Hexachlorobenzene tends to remain in the environment a long time.
Individuals may be exposed to hexachlorobenzene through several routes. Exposure to hexachlorobenzene can occur through breathing air and dust particles from sites where the chemical has been discarded. Also, exposure can occur through eating and drinking foods and liquids, such as milk, other dairy products, meat, and poultry. However, exposure to hexachlorobenzene through drinking water is unlikely because the compound does not dissolve readily in water.
Hexachlorobenzene has been found in shallow soils on the THAN site. The estimated dose for an individual exposed to hexachlorobenzene at levels found in shallow soil on the THAN site is much less than ATSDR's chronic MRL. Therefore, it is unlikely that non-cancerous adverse health effects will be caused by exposure to hexachlorobenzene at the THAN site.
Hexachlorobenzene is classified by the USEPA as a probable human carcinogen because it has lead to liver and thyroid cancer in animals. For workers who were exposed to hexachlorobenzene at the levels found in shallow soil on the THAN site for eight hours per day for five days a week for 47 years, the risk for cancer is estimated to be a very low risk. Therefore, we feel that hexachlorobenzene found at the THAN site is not a threat to human health.
Lead (23)
Lead is a bluish-gray metal with no characteristic smell or taste. It occurs naturally in small amounts in the earth's crust, but most of the lead in the environment comes from human activities. The amount of lead added to gasoline, paints, and other commonly used materials has been cut in recent years because of the harmful effects to humans and animals.
Exposure to lead is especially harmful to fetuses and children. Unborn children can be exposed to lead through their mothers. Exposure can cause premature births, low birth weights, and lowered mental ability in infants. Lead exposure has been shown to stunt growth and reduce intelligence quotient (IQ) scores in young children. In adults, lead exposure may decrease reaction time and perhaps memory function. Lead may cause weakness in fingers, wrists, or ankles. Middle-aged men may show an increase in blood pressure with exposure. High levels of exposure to lead can cause severe liver and brain damage to both children and adults. Exposure to high lead levels may cause spontaneous abortion in females, and can damage the male reproductive system. Animal studies have indicated that lead is a probable carcinogen, but there are insufficient human studies to support this theory.
ATSDR has not derived an MRL for lead. The USEPA has not determined an RfD because no thresholds have been demonstrated for the most sensitive effects in humans. Lead exposure may occur to CSX Transportation workers in the east ditch area and to workers exposed to on-site shallow soil. The Center for Disease Control has reported that significant elevations in blood lead levels occurs at concentrations of 1000 ppm or higher (28). The levels seen at the THAN site are much less than this level, and therefore should not cause a significant increase in blood lead levels or adverse health effects.
Manganese (24)
Manganese is silver-colored metal that occurs naturally in many types of rock and fossil fuels. It does not occur naturally as a pure metal; instead, manganese is found in combination with other elements such as oxygen, sulfur, and chlorine. These forms (compounds) do not evaporate, but small particles of solid manganese can become suspended in air. Some manganese compounds can dissolve in water, and low levels of these are found in lakes, streams, and oceans. Manganese does not break down or disappear from the environment, but it can change from one compound to another. Manganese compounds are mined and used in the production of steel, batteries, some ceramics, pesticides, fertilizers, and dietary supplements.
Because manganese occurs naturally in the environment, people are always exposed to low levels of it in water, air, soil, and food. Exposure to higher than normal levels of manganese occurs among workers in industries that use manganese. Most of this exposure is through breathing dust particles that contain manganese. People who live near coal or oil-burning factories, industries that use manganese or a major highway can be exposed to levels that are higher than normal.
Eating, drinking, or touching manganese is unlikely to result in harmful exposure. When swallowed, most manganese is excreted in the feces. Very little manganese is absorbed through the skin. When breathed into the lungs, dust particles containing manganese will be trapped, and some of the substance may then dissolve and enter the bloodstream. Particles that do not dissolve are eliminated by the body. Because manganese is normally found in the body, uptake is regulated. If the amount taken in is great enough, however, the body may not be able to adjust to the increased amount.
Small amounts of manganese are necessary to maintain human health, but too much can cause serious health effects. Workers exposed to high levels of manganese dust may develop manganism, a condition characterized by mental and emotional disturbances and slow, clumsy, body movements. The physical movement effects are caused because manganese permanently injuries the part of the brain that helps control movement. Exposure to high levels of manganese can cause impotence in men. In animal studies, exposure to manganese has caused injury to the testes. Little is known about how manganese exposure affects women, but animal studies suggest females may be less sensitive than males to associated health effects. The evidence in unclear on whether manganese causes birth defects in human infants. One animal study showed behavioral changes in offspring. More research is needed to determine the health effects of this metal on unborn children.
Manganese has been found in on-site shallow soils and sediment in the east ditch. The estimated dose for an individual exposed to manganese at levels found in on-site shallow soils is almost four times higher than the USEPA's chronic RfD. However, the RfD is set many times lower than the levels where health effects are observed in humans. The World Health Organization (WHO) estimates that an intake higher than the RfD is acceptable for dietary ingestion in humans (35). The intake proposed by WHO is many times higher than those intakes calculated for THAN workers. Therefore, adverse human health effects from manganese are considered unlikely.
The estimated dose for an individual exposed to manganese at levels found in east ditch sediments at the THAN site is slightly higher than the USEPA's RfD. However, the RfD is set a magnitude of 1000 below the level at which manganese causes adverse health effects in animals. Therefore, the manganese found in east ditch sediments at the THAN site poses no significant threat to workers who are exposed to manganese.
Although some animal studies have suggested that ingesting manganese may increase the risk for cancer, there is little evidence that it can cause cancer in humans. The USEPA has determined that manganese is not classifiable as to human carcinogenicity.
Naphthalene/2-Methylnaphthalene (32)
Naphthalene and 2-methylnaphthalene are discussed together in this section because they are related compounds. Naphthalene is a white solid substance that has a characteristic odor and evaporates easily. Naphthalene is commonly found in tar, mothballs, and toilet deodorant blocks. 2-Methylnaphthalene is also a solid substance and is used to make other chemicals such as dyes, resins, and vitamin K. Naphthalene enters the environment from industrial uses of this material. Naphthalene present at hazardous waste sites and landfills can dissolve in surface and underground water or become attached to soil. Scientists know very little about what happens to 2-methylnaphthalene in the environment. However, this compound has many similar properties to naphthalene, and thus should have similar reactions when exposed to air, soil, and water.
Exposure to naphthalene and naphthalene-related compounds can occur through inhalation, ingestion, or drinking of water that contains these chemicals. Naphthalene also can enter the body through dermal contact. Exposure to naphthalene has been shown to cause anemia in humans.
Naphthalene and 2-methylnaphthalene have been found in on-site shallow soils at the THAN site. The estimated amount of naphthalene and 2-methylnaphthalene ingested from on-site shallow soil is based on calculations used for soil ingestion. In comparing these exposures with those obtained from the scientific literature, the amount of naphthalene ingested by people at the site is many times less than the amount of naphthalene needed to cause health effects in humans or animals. Related compounds of naphthalene such as 2-methylnaphthalene are usually less toxic, and do not cause anemia even in high concentrations. Summing the oral exposures for naphthalene and related compounds results in an overall exposure that is many times lower than the adverse effect levels for naphthalene in humans and animals. Therefore, we feel that no non-cancerous adverse health effects are expected from the ingestion of naphthalene and other related compounds at the THAN site.
Naphthalene and 2-methylnaphthalene are not known to cause cancer.
Toxaphene (19)
Toxaphene is a solid pesticide that smells like turpentine. It is a mixture of over 670 chemicals. The chemical does not occur naturally, but is a common environmental contaminant because of past agricultural practices. Toxaphene vaporizes readily when in solution, but does not dissolve easily in water. It sticks to soil particles, and can persist for weeks or even years in soil, water, or air.
Toxaphene has been banned in the United States for most uses since 1982, but it was once one of the most heavily used insecticides in the country. It was used heavily in the southern states to control insects on cotton and other crops. In addition, toxaphene was used to kill unwanted fish species in lakes. The chemical can still be used to control insect pests on livestock or in emergency situations, as determined by the USEPA.
Exposure to toxaphene can occur through breathing, skin absorption, and eating or drinking water containing the substance. Because it vaporizes so readily, inhalation is the most likely route of exposure. Toxaphene does not appear to accumulate in the body.
Toxaphene has been found in sediment in the east ditch. The estimated dose for an individual exposed to toxaphene at levels found in east ditch sediments at the THAN site is much less than ATSDR's chronic oral MRL. Therefore we feel that no adverse health effects will result from exposure to toxaphene at the THAN site.
Studies of toxaphene has been found it to cause liver tumors in animals. The USEPA has classified toxaphene as a probable human carcinogen based on these studies. For workers who were exposed to toxaphene at the levels found at the THAN site for eight hours per day for five days a week for 47 years, the increased cancer risk for liver cancer is estimated to be very low. Therefore, we feel that toxaphene found at the THAN site is not a threat to human health.
Other Compounds
Thallium, 4-methyl-2-pentanone, endrin aldehyde, and endrin ketone were found in shallow soil on the THAN site. These compounds have no comparison values because there are insufficient studies to determine whether these compounds will cause adverse health effects in humans. Therefore, these compounds will not be evaluated in this document.
Other Metals
Calcium, cobalt, copper, iron, magnesium, potassium, and sodium were found in the east ditch. These substances are essential nutrients necessary for human biological functioning, and are not considered hazardous at the levels detected. Aluminum was detected at the site, also. No comparison value is available for aluminum. However, since it is not readily absorbed by the human body, we judge is unlikely to cause adverse health effects. Because of these factors, we will not discuss these metals further in this report.
B. Health Outcome Data Evaluation
Health outcome data was evaluated by ADPH in response to community concerns that have been raised during the health assessment process. The data was not evaluated because the public health assessment indicates that there are increased rates of disease in the general community. At present, there are no completed pathways for contaminants to reach the general neighborhood surrounding the THAN site.
Some limitations do exist when using county wide statistics to show a correlation between the site and health effects in the general community. The neighborhood surrounding the site is a small population that may vary in sex, race, age, and economic status from the county as a whole. These factors can create health statistics for the general community that are very different from the county's health statistics. Thus, caution should be used when using county wide statistics to show a correlation between a site and the health effects in the community surrounding the site.
According to the 1992 Alabama Vital Events report, the cancer mortality rate for Alabama was 221.2 deaths per 100,000 population. The Montgomery County cancer mortality rates for the same period was 213.0 cancer deaths per 100,000 population, respectively. The cancer mortality rate in 1992 for whites was 230.8 cancer deaths per 100,00 population. The rate for blacks and others during the same time period was 209.8 per 100,000 population. However, it is unlikely that the difference in cancer rates is related to exposure to contaminants from the THAN site because there is no completed exposure pathway for contaminants to reach the general community.
Infant mortality for the state and Montgomery County was examined and compared. The infant mortality rate for Alabama in 1992 was 10.5 per 1,000 live births. During the same period, infant mortality for Montgomery County was 14.0 per 1,000 live births. The rates in Montgomery County were 7.5 and 15.8 per 1,000 live births for whites and blacks, respectively. The infant mortality rates for Montgomery County, all races, and for blacks are higher than the state and national rates. However, it is unlikely that the difference is attributable to exposure to contaminants from the THAN site because there is no completed exposure pathway for contaminants to reach the general community.
C. Community Health Concerns Evaluation
Air Exposure Health Concerns
It is likely that past exposure did occur when workers did not wear protective equipment. However, without knowing the type of contaminant(s), the concentration of the contaminant(s), and length of exposure there is no way to assess whether there are health affects caused by the contaminated dust.
Because of the historical nature of the chlorine releases at the site and the short and intermittent exposure that may have occurred, we cannot assess whether any long-term health effects resulted from past occupational exposures to chlorine gas. However, chlorine gas, either by inhalation or dermal exposure, can cause skin irritations and respiratory problems. It is possible that high levels of exposure to chlorine gas can cause long-term health effects. Exposure to chlorine gas is not a current problem for site workers.
Ambient air data show that air is not a transport medium for contaminants. Furthermore, contaminants of concern found in on-site soils and sediments are not likely to be blown off-site because most of the THAN site is covered with grass, small trees, and shrubs. Additionally, the THAN site is surrounded by large trees and dense vegetation that act as barriers to protect the surrounding communities from airborne contaminants
Ingestion Exposure Concerns
At the present time, no fish from the ponds have been tested for contamination. However, both sediment and surface water from the ponds were sampled. Neither medium of transport contained any contaminants of concern above ATSDR comparison values. Because of the lack of contamination in sediments and surface water, no source of contamination is available for bioaccumulation in the fish.
The City of Montgomery municipal well that is closest to the site was sampled, and no contamination was detected. There exists no present completed exposure pathway to domestic well water because most residences within a two-mile radius of the site are supplied by the City of Montgomery water supply. At present, no evidence exists to suggest that past exposure from domestic water drawn from shallow wells and intermediate wells has taken place. The two plumes in the shallow aquifer currently extend about 2900 feet from the southwest corner of the site. The extent of the plume at intermediate well depth has not been determined. However, taking into account the speed of the groundwater flow in the Alluvial/Terrace aquifer (30 feet per year) and the rate of dispersion for the contaminants, it is unlikely that site contaminants would have reached domestic wells because the spatial extent of the plumes would have been less in the past.
Contaminants which are not related to the site (TCE and tetrachloroethene) cannot be evaluated at the present time. There is not enough data to determine the extent of the plume, the amount of time that the contaminants have been present, or if an exposed population exists.
No contaminants of concern have been detected in surface water from the ponds in the Twin Lakes community. Therefore, no adverse health effects are likely.
Other Health Concerns
At this time, no shallow soil samples have been taken from the Twin Lakes community. Since sediment and surface water samples taken from the Twin Lakes community ponds showed no contaminants, it is unlikely that surface soil has been effected. Also, ambient air data suggest that air is not, has not, and will not be an exposure pathway for contaminants to leave the site. Therefore, children playing in the soil should not experience any adverse health effects related to contaminants of concern from the THAN site.
There is no known exposure pathway by which contaminants can reach residents in the community. Because there is no exposure to contaminants from the THAN site, there should be no site-associated health risks from doing yard work.
No known exposure pathway exists for contaminants to reach the residents in the Twin Lakes community. Therefore, there should be no risk to fetuses or infants due to contaminants migrating off-site. If residents do enter the THAN site or areas where contamination has migrated off-site, the risk to infants does increase greatly because they have an increased sensitivity to toxic substances. However, an increased risk to fetuses is not likely.
The rate of cancer for the general community is not known at this time. Currently, ADPH is conducting a health consultation in a community west of the site to determine if the community does have a higher incidence of cancer. The rates reflected in the health outcome data section shows that Montgomery County has a lower rate of cancer when compared to the state rate. However, whites in Montgomery County do have a higher rate of cancer than blacks. It was noted previously that the community surrounding the THAN site is 68% white. This does not mean that the rate in the community surrounding the THAN site is high because there are limitations to using county wide statistics to show a correlation between the site and health effects in the general community.
At this time, there is no known completed exposure pathway to the community for site related contaminants of concern. Consequently, there should be no site associated increase in cancer rates in the community. However, this does not rule out the possibility that other off-site factors may be contributing to this rate.
There is no known completed exposure pathway to the Twin Lakes community that could be causing these health concerns. If residents do trespass on the THAN site or enter off-site areas that are contaminated, it is unlikely that these adverse health effects would occur. Inhalation of contaminated air s needed for most of these health effects to happen. However, an ambient air pathway does not exist for THAN. Arsenic is known to cause a darkening of the skin, yet it has not been reported to cause red splotches.
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