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PUBLIC HEALTH ASSESSMENT

UNION PACIFIC RAILROAD YARD
SACRAMENTO, SACRAMENTO COUNTY, CALIFORNIA


COMMUNITY HEALTH CONCERNS

CDHS staff contacted the Department of Toxic Substances Control (DTSC) staff about the siteabout any health concerns that the community might have shared with them. DTSC staff havebeen working with the community for several years as it regards the site investigation andcleanup activities. Community members are concerned about suitable future development of thesite and issues and constraints involved in reuse of the site and the necessity of taking healthconcerns into account.


ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

In order to assess the potential adverse health effects of environmental contamination on a nearbypopulation, one must first identify those contaminants which are present at a high enoughconcentration to possibly cause adverse health effects. Those contaminants so identified arecalled contaminants of concern, and are identified as follows.

Identification of contaminants of concern is based on a comparison of the concentration of thecontaminant in a specific medium (soil, air, water) compared to a screening value for thatcontaminant in that medium. This screening value is the concentration of a specific chemical in aspecific medium (soil, air, water) at or below which a person could be exposed to that chemicalwithout the expectation of adverse health effects occurring. These values are calculated usingvery conservative assumptions regarding the body weight and ingestion rate of the receptorpopulation, so that if the concentration of the contaminant is below the screening value, oneshould feel confident that adverse health effects should not occur. If the concentration of thecontaminant exceeds the screening value, then it is called a contaminant of concern. However,adverse health effects do not automatically occur if the concentration of a chemical exceeds itscomparison value. The chemical must then be further evaluated on an individual basis todetermine the likelihood of the occurrence of adverse health effects.

ATSDR uses screening values for both cancer and non-cancer adverse health effects. These aredescribed below.

ATSDR uses several types of screening values to evaluate contaminants of concern for their potential to cause non-cancer adverse health effects. The primary screening value that ATSDR uses is called an Environmental Media Evaluation Guide (EMEG). An EMEG is a concentration of a chemical in soil, air, or water, above which a person might experience adverse health if exposed to that chemical. EMEGs are based on a Minimal Risk Level (MRL), which is the daily dose (mg/kg/day) of a chemical to which a person could be exposed without experiencing adverse health effects.

If there is no MRL or other similar value for a chemical, then other values are used. Lead doesnot have an MRL. CDHS opted to use the California Environmental Protection AgencyPreliminary Remediation Goal (PRG) for lead as its screening value. Preliminary remediationgoals (PRGs) have been developed by the U.S. Environmental Protection Agency (USEPA) andin some cases the California Environmental Protection Agency to screen pollutants inenvironmental media, trigger further site investigation, and provide an initial cleanup goal, ifapplicable. PRGs are risk-based concentrations that typically correspond to either a one in amillion increased cancer risk or a non-carcinogenic hazard quotient of one. The PRG for lead isbased on a mathematical model to estimate blood-lead levels for children or adults on the basis oftotal lead uptake from exposures via diet, drinking water, air, and soil. In this model, the bloodlead concentration of concern in children is 10 micrograms per deciliter of whole blood, based ona non-cancer endpoint.

The screening value that ATSDR uses to identify carcinogenic contaminants of concern is calleda Cancer Risk Evaluation Guide (CREG). A CREG is the concentration of a chemical in aspecific medium (air, soil, water) that would be expected to cause a greater than 1 x 10-6 increasein the lifetime cancer risk (see Toxicological Evaluation Section for more discussion aboutcancer risk).

Toxic Release Inventory Data

During the assessment of the Union Pacific site, the preparers of this report searched the ToxicRelease Inventory (TRI). TRI is an on-line database, maintained by the USEPA, containinginformation (self-reports from the facilities) about more than 400 different substances releasedfrom facilities into the environment from 1992-1996.

Emissions from currently operating nearby facilities may be contributing an additional burden to the nearby population. CDHS staff searched the TRI asking for all facilities located within the zip code of the Union Pacific facility. TRI contains information on estimated annual releases (emission rates) of toxic chemicals to the environment (via air, water, soil, or underground injection) whether these releases are routine releases, spills, and other accidental releases, or occasional releases from normal operations. Toxic chemical release information is submitted to USEPA by certain industries mandated under the Emergency Planning and Community Right to Know Act of 1986.

One facility located in the zip code 95818 reported the release of 1,000 lbs per year of ammoniaevery year from 1992 to 1996. No other releases were reported for facilities located in that zipcode.

A. On-Site Contamination

In this section, we will briefly mention the contaminants found on-site; so as to understand whatchemicals may have migrated off-site.

Soil Investigations

Investigations by Union Pacific and its contractors in 1992 found elevated levels of arsenic, copper, lead, and zinc in soils from the surface to 1 to 2 feet below ground surface (3). The dominant source of these metals seemed to be from the slag tack ballast. Union Pacific and its contractors conducted an evaluation of the slag material for potential mobility of arsenic and lead. They found that the solubility of arsenic in the slag is relatively low, because the metals are bound tightly to the slag material. In 1993, most of the slag was removed from the site.

Selenium, copper, and cobalt were not found at elevated levels in the on-site soils and thus are not chemicals of concern. Arsenic and lead were also found in the area of the site where locomotives and rail cars were formerly repaired (3). Petroleum hydrocarbons were also found in the soil in this repair area.

Groundwater Investigations

As a result of groundwater investigations conducted by Union Pacific and its contractors, three plumes of contaminated groundwater have been detected. The largest plume contains chlorinated volatile organic compounds such as carbon tetrachloride, trichloroethylene, vinyl chloride and volatile aromatic organic compounds such as benzene, toluene, ethylbenzene, xylenes, and nickel (2). This plume extends from the Central Fill Area to the southeast approximately 5,200 feet. The smaller plume, which contains lower concentrations of volatile organic compounds andnickel, extends from the former Main Shop area approximately 1200 feet to the south, just pastthe site boundary and Sutterville Road. The third plume, which contains diesel fuel and oil, islocated in the northeast portion of the site, and is contained within the site boundary.

B. Off-Site Contamination

In this section, we will focus on off-site soil contamination, contaminant migration via the air,and groundwater contamination as it may have affected the nearby residents, including thepetitioners.

Off-site surface soil investigation and remediation

Before describing the surface soil lead and arsenic contamination found in and around the site, it is helpful to provide the typical levels of these metals in Sacramento area soils. In 1990, under the direction of DTSC, contractors for Union Pacific collected nine samples from Curtis Park and William Land Park to evaluate background concentrations of arsenic and lead (3). The concentrations of arsenic ranged from 6.36 to 8.36 ppm, with an average of 7.75 ppm. The concentrations of lead ranged from 7.80 to 30.0, with an average of 22.0 ppm. For purposes of the subsequent discussions, we will call these background concentrations.

In 1991, DTSC initiated an investigation in the off-site area west of the site to address the issue of chemical migration from the site (4). In January, May, June, and July 1991, contractors for Union Pacific collected soil samples from four vacant lots (Lots 1, 2, 3, and 4), three residential lots (2206 6th Avenue, 2207 7th Avenue, and 2212 7th Avenue), and one commercial lot (2177 Perkins Way) located on the western edge of the Union Pacific site (Figure 2). The first six-inches or the first foot of soil was collected. These samples were analyzed for arsenic and lead (Table 1, data for the commercial lot not shown).

The average concentration of lead exceeded the health comparison value (170/400 ppb) in Lot 1. In the other three lots and at the residential properties, the average concentrations of lead in thesurface soil did not exceed health comparison values. Based on this data, lead is considered acontaminant of concern in Lot 1, but not in the other lots and not in the residential property.

The arsenic levels in the soil measured in early 1991 at Lot 1, Lot 3, and 2206 6th Avenueexceed the average background concentrations and exceed the health comparison value forcancer (0.6 ppm), non-cancer for a child (20 ppm) and non-cancer for a pica child (0.5 ppm). Thus arsenic is considered a contaminant of concern for Lot 1, Lot 3, and 2206 6th Avenue. Theaverage arsenic levels measured in surface soil samples taken from Lot 2, Lot 4, 2206 6th Street,2207 7th Street, and 2212 7th Street are roughly at background concentrations and thus arsenic isnot considered a contaminant of concern for these properties.

Based on these results, DTSC directed Union Pacific to remove the metal impacted soil from Lot 1 and 2206 6th Avenue and to minimize the exposure from the contaminated soil in Lot 3 (4). The upper one foot of soil from Lot 1, from a portion of Lot 3, and from a portion of 2206 6th Avenue was excavated and removed. Union Pacific contractors imported and compacted clean soil on Lot 1 and 2206 6th Avenue, imported and compacted a gravel cover on Lot 2, and placed an aggregate base with a bituminous sealcoat over Lot 3. Thus any exposures that might have occurred on Lots 1, 2, and 3 and at 2206 6th Street have ceased.

After looking at aerial photos, DTSC believes that the contamination problems in Lots 1 and 2206 6th Avenue were a result of arsenic- and lead-contaminated slag being applied as a groundcover to the parking lot for the office buildings located nearby (4). Even in the old maintenance yard there was no elevation of copper, cobalt, or selenium in the on-site surface or subsurface soil, thus there is no reason to suspect that these chemicals would be found distributed in the neighborhood as a result of activities at the Union Pacific site.

Air Investigations

Union Pacific and its contractors have conducted three separate ambient air quality studies toexamine the migration through the air of certain contaminants from the site. Each of the studieshad a sampling location on the western side of the site adjacent to the nearest residences. Thefirst air monitoring study was conducted in 1988 and by that time the maintenance activities atthe site were no longer occurring. Thus, all three air monitoring studies reflect the aircontamination resulting from normal railroad movement occurring on-site since the closing ofthe maintenance yard in 1983.

In 1988, contractors for Union Pacific collected air samples at three stations, one located upwind and two located downwind, over an eleven-day period (3). The samples were analyzed for arsenic, copper, lead, and dust. Air samples collected for 12 hours per day were analyzed for asbestos. No detectable levels of copper (detection limit= 0.32 mg/m3) or lead (detection limit=0.58 µg/m3) were found. Arsenic was detected on one day (0.006 µg/m3) at the upwind station and that same day arsenic was detected at one of the two downwind stations (0.012 µg/m3). On another day, arsenic was detected (0.006 µg/m3) at one of the downwind stations but not at the other downwind station nor at the upwind station. Of thirty samples analyzed for asbestos, one sample was found to contain asbestos at a very low concentration.

Union Pacific contractors conducted a second air quality study in July and August 1992 (5). For this study, 24-hour air samples were collected each day at six stations over a 14-day study period. Two sampling stations were located upwind of the site to measure background air contaminant concentrations. Three sampling locations were placed downwind to provide an indication of how soil contaminants affect air quality near the site. One sampling location was placed at the edge of the Union Pacific property near 7th Avenue residences, essentially crosswind to the wind flow relative to the site. Air samples were analyzed for arsenic, lead, and asbestos. The average concentrations were slightly higher at the upwind sampling stations for lead (0.0109 µg/m3) compared to the downwind stations (0.0064 µg/m3) and the crosswind station (0.0086 µg/m3). This indicates that lead was not migrating off the site during the monitoring period that occurred in July and August 1992. The average concentrations of arsenic at the upwind (0.0004 µg/m3), crosswind (0.0005 µg/m3), and downwind (0.0003 µg/m3) stations were essentially the same, indicating that arsenic was not migrating off the site during the monitoring period that occurred in July and August 1992 (5).

In the 1992 sampling, asbestos fibers were detected (detection limit= 0.004 structures/cc) on six of the 28 samples collected at the two upwind stations (5). Asbestos fibers were detected on nine of the 38 samples analyzed from the downwind stations and on two of the 14 samples collected at the crosswind sampling station. The average of the asbestos analyses was slightly higher for the downwind stations (0.0034 structures/cc) compared to the upwind station (0.0029 structures/cc)(5). The average concentration of asbestos measured at the crosswind station (0.0023 structures/cc) was lower than either the upwind or downwind stations. [For average calculations, a non-detect concentration was assumed to be 0.002 structures/cc or ½ the detection limit.] Overall, it does not seem that asbestos is often detectable in the air around the Union Pacific site and it does not seem as though asbestos was migrating from the site during the monitoring period in July and August 1992.

Dames and Moore, contractors for Union Pacific, conducted a third air monitoring round in 1994 (6). The air monitoring program consisted of three five-day sampling rounds aimed at collecting particulate generated during normal working hours around the area of the active railyard where the greatest amount of work activities and vehicular traffic occurs. The particulate samples were analyzed for arsenic and lead. One of the five sampling stations was located at the site boundary adjacent to Lot 2, near the western residences. Arsenic was never detected in the air samples collected from the sampling location near Lot 2. Lead was detected at a maximum concentration of 0.0169 µg/m3 in the sampling location near the residences. This concentration is lower than what was detected at the upwind, off-site location and is lower than the sample collected directly next to the active area of the site. Overall, this indicates that arsenic and lead did not migrate from the site in the direction of the petitioners' homes during those three sampling periods in 1994.

Groundwater Investigations

As mentioned previously, two of the three groundwater plumes have migrated off-site. The largest plume contains chlorinated volatile organic compounds such as carbon tetrachloride, trichloroethylene, vinyl chloride and volatile aromatic organic compounds such as benzene, toluene, ethylbenzene, xylenes, and nickel (2). This plume extends from the Central Fill Area to the southeast approximately 5,200 feet. The smaller plume, which contains lower concentrations of volatile organic compounds and nickel, extends from the former Main Shop area approximately 1200 feet to the south, just past the site boundary and Sutterville Road.

The seven wells located nearest to the groundwater plumes, all of which are agricultural wells, are sufficiently far from the groundwater plume that they will not be affected. And the nearest downgradient drinking water wells, located approximately one and one-half miles, are not threatened by the groundwater contamination (3).

The petitioners' residences are not located over any of the groundwater plumes, so there is nocompleted or potential exposure from the trapping of soil gases migrating from the contaminatedgroundwater through the soil column and accumulation indoors. Even for those residences thatare located over the groundwater plumes, an exposure is unlikely because the groundwater levelis so far below the ground surface (25 to 35 feet bgs).

C. Quality Assurance and Quality Control

In preparing this report, CDHS and ATSDR relay on the information provided in the referenceddocuments and assume that adequate quality assurance and quality control measures werefollowed with regard to chain-of-custody, laboratory procedures, and data reporting. Theaccuracy of the conclusions contained in this public health assessment is determined by thecompleteness and reliability of the referenced information. Environmental sampling and analysiserror can result from the error inherent in the analysis procedures, from a failure to take anadequate number of samples to characterize a medium, from mistakes on the part of the sampler,or from the heterogeneity of the medium being sampled. Procedural or systematic error can beminimized through the use of quality control procedures such as duplicate samples and blanks. Quality control measures reported by Union Pacific and its contractors do not indicate any majorproblems with the field or laboratory procedures.

D. Physical and Other Hazards

Observations made at the time of the site visit did detect very large trains that pass through thesite and could pose a health hazard; however, the site is surrounded by a fence and thus themovement of the train through the site should actually pose less of a health hazard than at otherplaces along the train track route. No other physical hazards were observed.


PATHWAYS ANALYSES

For a target population to be exposed to environmental contamination, there must be a mechanism by which that contamination comes into direct contact with the target population (8). An exposure pathway is the description of this mechanism and it consists of five parts: a source of contamination, an environmental medium and transport mechanism, a point of exposure, a route of exposure, and a receptor population. An exposure pathway may be classified as completed, potential, or eliminated (8). A complete exposure pathway is one in which all five elements of the pathway are present or were present in the past. If any one of these is missing, then there is no exposure, though the presence of contamination may still be significant and require remediation. A potential pathway has one of the elements missing but may become complete in the future. An eliminated pathway is one in which one or more of the elements is missing and will never be complete.

CDHS considers that no current exposure pathway exists for residents living near the UnionPacific site because: 1) air monitoring indicates that contamination is not moving from the sitewith current use; 2) no one is drinking the contaminated water emanating from the site and themunicipal water that serves the neighborhood is of good quality; and 3) current soil levels do notindicate that contamination from the site exists in the neighborhood yards at levels of healthconcern.

CDHS considers that past exposure to contaminants in the soil may have occurred for residents who lived at 2206 6th Avenue (not the home of either petitioner). This exposure may have occurred as result of gardening, playing or other activities that resulted in someone having contact with soil. The contaminated soil has been removed so this pathway has been eliminated, the past exposure will be evaluated in the toxicological evaluation section (Table 2).

Past exposure to the drinking water is also an eliminated pathway since no one ever drank thecontaminated water and the municipal water that served the neighborhood, including thepetitioners' residences is of good quality.

Since no air modeling was conducted at the site when it was an active railroad maintenance yard, it is not possible to evaluate whether or not the air pathway occurred at a level of health concern in the past. Thus this is considered a potential exposure pathway that may have occurred in the past (Table 3).


PUBLIC HEALTH IMPLICATIONS

A. Toxicologic Evaluation

The following section evaluates the potential health effects that may have resulted from exposureto the lead and arsenic in the soil at 2206 6th Avenue, the only completed exposure pathwayidentified at the Union Pacific site. Two subgroups of the receptor population, children andadults, will be evaluated.

To link the human exposure potential of the site with health effects that may result from site-specific conditions, ATSDR and CDHS estimate human exposure site contaminants by way of ingestion, inhalation, or dermal contact.

In order to understand the health effects that may be caused by a specific chemical, it is helpful toreview factors related to how the human body processes a chemical after exposure. These factorsinclude the exposure concentration (how much), the duration of the exposure (how long), theroute of exposure (breathing, eating, drinking or skin contact), and the multiplicity of exposure(combinations of exposure). Once exposure occurs, individual characteristics such as age, sex,nutritional status, health status, lifestyle, and genetic make-up influence how the chemical isabsorbed, distributed, metabolized (processed), and excreted (eliminated). Together, thesefactors determine health effects that exposed people may have.

To evaluate non-cancer health effects, ATSDR has developed Minimal Risk Levels (MRLs) for contaminants commonly found at hazardous waste sites (8). The MRL is an estimate of daily human exposure to a contaminant below which non-cancer adverse health effects are unlikely. MRLs are developed for ingestion and inhalation and for the length of exposure (acute, up to 14 days; intermediate, 15 to 364 days, and chronic, 365 and more). MRLs are derived most often from animal exposure studies, though some are calculated from human exposure studies.

ATSDR has published an MRL for arsenic (9). ATSDR has not published an MRL for lead (10). Instead, the preparers of this report used the California Department of Toxic Substances Control mathematical model that integrates lead exposure from several pathways in order to arrive at an estimated distribution of blood lead concentrations that may be expected in a population of children or adults (11).

To evaluate the potential for a contaminant to cause cancer in an individual or population is evaluated by estimating the probability of an individual developing cancer over a lifetime as the result of the exposure. This approach is based on the assumption that there are no absolutely "safe" toxicity values for carcinogens. USEPA has developed cancer slope factors for many carcinogens. A slope factor is an estimate of a chemical's carcinogenic potency, or potential, for causing cancer. An estimate of excess cancer risk associated with a chemical exposure is calculated using the slope factor for that carcinogen multiplied by the dose.

USEPA, the International Agency for Research on Cancer (IARC), and the Department of Health and Human Services (DHHS) National Toxicology Program (NTP) review available information from human and/or animal studies to determine whether certain chemicals are likely to cause cancer in humans. Arsenic is considered a known human carcinogen based on sufficient human evidence by the USEPA (termed a Class A carcinogen), by IARC (termed a Class 1 carcinogen), and by the NTP (termed a Class 1 carcinogen)(9). USEPA has published a cancer slope factor for arsenic. Lead is considered a probable human carcinogen based on inadequate human studies but sufficient animal studies (termed a Class B2 carcinogen)(10); however, the USEPA has not published a cancer slope factor for lead, so the carcinogenic risk from chronic exposure to lead can not be calculated. IARC has determined that lead is not classifiable as a carcinogen (termed Class 3).

Cancer risk is the likelihood, or chance, of getting cancer. We say "excess cancer risk" becausewe have a "background risk" of about one in four chances of getting cancer. In other words, in amillion people, it is expected that 250,000 would get cancer from a variety of causes. If we saythere is a "one in a million" excess cancer risk from a given exposure to a contaminant, we meanthat if one million people are exposed to a carcinogen at a certain level over a very long period oftime, then one cancer above the background chance, or the 250,001st cancer, may appear in thosemillion persons from that particular exposure. In order to take into account the uncertainties inthe science, the risk numbers used are plausible upper limits of the actual risk based onconservative assumptions. In actuality, the risk is probably somewhat lower than that calculated,and in fact, may be zero.

In these discussions of the toxicological effects of lead and arsenic, the average and maximumconcentrations of the contaminants of concern are considered. Ordinarily, people will not beexposed to contaminants in the soil at just one location or just at the maximum concentration.Rather, they will be exposed to contaminants in several locations in an area. Thus, the averageconcentration of the contaminant would be a more realistic measure of exposure. However, themaximum concentration of a contaminant is also considered here to provide a worst-casescenario.

Before evaluating the health impact for the completed exposure pathway at the Union PacificSite, a brief summary of the toxicological concerns for arsenic and lead is presented.

Arsenic

Arsenic is a naturally-occurring element (9). Inorganic arsenic occurs naturally in many kinds of rock, especially in ores that contain copper and lead. Because arsenic is a natural part of the environment, low levels of arsenic are present in soil, water, food, and air.

If one swallows arsenic in water, soil, or food, most of the arsenic quickly enters into the body (9). If one breathes air that contains arsenic dust, many of the dust particles settle into the lining of the lungs. Most of the arsenic in these dust particles is then taken up into the body. If one gets arsenic-contaminated soil or water on the skin, only a small amount will go through the skin into the body, so this is usually not a concern.

Inorganic arsenic at the lower doses than would typically be seen from exposure to arsenic around a hazardous waste site has been shown to cause skin changes, cardiovascular and gastrointestinal effects (9). For example, arsenic in doses as low as 12 x 10-3 mg/kg/day in adults may produce one or more characteristic skin lesions, vascular lesions, and gastrointestinal irritation. Slightly higher levels (19 x 10-3 mg/kg/day) have been shown to affect the liver. Although there is no good evidence that arsenic can injure pregnant women or their fetuses, studies in animals show that doses of arsenic that are large enough to cause illnesses in pregnant females may cause low birth weight, fetal malformations, or even fetal death. Swallowing arsenic has been reported to increase the risk of cancer in the liver, bladder, kidney, and lung.

Lead

Lead is a naturally-occurring element found in small amounts in the earth's crust (10). However, most of the lead found throughout the environment comes from human activities, including the burning of leaded gasoline before it was banned and the weathering and chipping of lead-based paint. Mining wastes that have been used for sandlots, driveways, roadbeds, or railway bed can be sources of inorganic lead.

A person can be exposed to lead and chemicals that contain lead by breathing air, drinking water, eating foods, or swallowing or touching dust or dirt that contains lead (10). Skin contact with dust and dirt containing inorganic lead occurs every day. However, not much lead can get into your body through your skin.

Shortly after lead gets into your body, it travels in the blood to the "soft tissues" (such as the liver, kidneys, lungs, brain, spleen, muscles, and heart)(10). After several weeks, most of the lead moves into your bones and teeth. In adults, about 94% of the total amount of lead in the body is contained in the bones and teeth. Only about 73% of the lead in children's bodies is stored in their bones. Some of the lead can stay in your bones for decades: however, some lead can leave your bones and reenter your blood and organs under certain circumstances, for example during pregnancy and periods of breast feeding.

Lead is an element that affects the nervous system, the blood system, the kidneys, and the reproductive system (10). Developmental effects are seen at very low levels: decrements in I.Q. are seen in children of women with only 10-16 µg lead/deciliter (dl) umbilical cord blood. Alterations in heme synthesis (a component of red blood cells and enzymes) occur when blood lead concentrations reach 15 to 30 µg/deciliter. Anemia, a blood disorder, occurs at 75 m/dl blood in children and at 80-85 µg/dl in adults.

The risk of premature birth increases fourfold as cord or maternal blood lead levels increase from less than 8 to 14 µg/dl (10). Lead in humans is associated with reproductive toxicity resulting in such symptoms as miscarriages and decreased fertility, and with sperm abnormalities at 40 to 50 µg/dl.

There is no direct proof that lead causes cancer in humans (10). Kidney tumors have developed in rats and mice given large doses of lead. However, the animal studies have been criticized by a panel of USEPA scientists because of the very high doses used, among other things.

Toxicological Evaluation of Children Exposed to Arsenic and Lead in the Soil at 2206 6th Avenue

ATSDR and CDHS recognize that infants and children may be more sensitive to exposures thanadults in communities with contamination in their water, soil, air, or food. This sensitivity is aresult of a number of factors. Children are more likely to be exposed to soil or surface waterbecause they play outdoors and often bring food into contaminated areas. For example, childrenmay come into contact with and ingest soil particles at higher rates than adults do; also, somechildren with a behavior trait known as "pica" are more likely to ingest soil and other non-fooditems. Children are shorter than adults, which means they can breathe dust, soil, and any vaporsclose to the ground. Also, they are smaller, resulting in higher doses of chemical per bodyweight. The developing body systems of children can sustain permanent damage if toxicexposures occur during critical growth stages. Because children depend completely on adults forrisk identification and management decisions, ATSDR is committed to evaluating their specialinterest at applicable sites as a part of the ATSDR Child Health Initiative.

This section evaluates potential adverse health effects on children who might have been exposed to arsenic and lead through incidental ingestion of contaminated soils at 2206 6th Avenue. Because the areas with the highest levels of contamination have been cleaned up, these potential adverse health effects are based upon past exposures to contaminated soils. For the purposes of evaluating potential adverse health effects to arsenic, the preparers of the report assumed a child weighs 10 kg (approximately 22 pounds) and incidentally ingests 200 mg of contaminated soil per day. At an average arsenic concentration of 140 ppm, the daily dose of arsenic to a child who might have been exposed to the backyard contaminated soil before it was cleaned up is 2.8 x 10-3 mg/kg/day. If that child were exposed to the highest concentration of arsenic in the backyard soil (614 ppm), then the daily dose of arsenic would have been 12.3 x 10-3 mg/kg/day. The dose received from exposure to the average concentration of arsenic in the soil does exceed the chronic oral MRL (0.3 x 10-3 mg/kg/day), but does not exceed the lowest dose (12 x 10-3 mg/kg/day) for which non-cancer health effects have been seen in adults (similar information is not available for children). Thus, before the fall of 1991 when the backyard was cleaned up, children exposed to the highly contaminated soils on a daily basis for periods greater than one year probably would not have experienced adverse health effects. The dose received from exposure to the maximum concentration of arsenic in the soil does exceed the chronic oral MRL and slightly exceeds the lowest dose (12 x 10-3 mg/kg/day) for which non-cancer health effects have been seen in adults (similar information is not available for children). Therefore, before the fall of 1991 when the backyard was cleaned up, children who played in the more highly contaminated area of the backyard on a daily basis for periods greater than one year may have experienced adverse health effects, such as skin changes.

For the purposes of evaluating potential adverse health effects to lead, lead in air was assumed to be 0.0169 µg/m3 (the highest concentration of lead measured from the three air monitoring studies)(6) and lead in water was assumed to be 5 µg/l (the concentration of lead in the water that is served by the City of Sacramento Water District to this area from the Sacramento River treatment facility)(7). At an average lead concentration of 56 ppm, the predicted blood-lead level (BLL, 99th percentile) in a child who might have been exposed to the backyard contaminated soil before it was cleaned up is 6.4 µg/dL. At a maximum lead concentration of 222 ppm, the predicted BLL (99th percentile) is 9.9 µg/dL. The Center for Disease Control and Prevention recommends intervention for children with blood lead levels of greater than 10 µg/dL (12). The Food and Drug Administration considers the Lowest Observable Adverse Effect Level (LOAEL) for children to be 10 µg/dL (13) Thus, before the fall of 1991 when the backyard at 2206 6th Avenue was cleaned up, children were not at risk for adverse health effects when they were exposed on a daily basis to the average lead or evan the maximum concentration of soil in the backyard.

Toxicological Evaluation of Adults Exposed to Arsenic and Lead in the Soil at 2206 6th Avenue

For the purposes of evaluating potential adverse health effects to arsenic, the preparers of thereport assumed an adult weighs 70 kg (approximately 154 pounds) and incidentally ingests 100mg of contaminated soil per day. At an average arsenic concentration of 140 ppm, the daily doseof arsenic to an adult who might have been exposed to the backyard contaminated soil before itwas cleaned up is 0.2 x 10-3 mg/kg/day. If that adult were exposed to the highest concentration ofarsenic in the backyard soil (614 ppm), then the daily dose of arsenic would have been 0.88 x 10-3mg/kg/day. The dose received from exposure to the average concentration of arsenic in the soildoes not exceed the chronic oral MRL for arsenic of 0.3 x 10-3 mg/kg/day, indicating thatnon-cancer health effects would not have not been experienced. The dose received fromexposure to the maximum concentration of arsenic in the soil does exceed the chronic oral MRL,but does not exceed the lowest dose (12 x 10-3 mg/kg/day) for which non-cancer health effectshave been seen in adults. Thus, before the fall of 1991 when the backyard was cleaned up, adultsexposed to the highly contaminated soils on a daily basis for periods greater than one yearprobably would not have experienced adverse health effects.

Residents who lived at 2206th Avenue and were exposed over their entire lifetime to the averagearsenic soil concentrations measured in their backyard in 1991 would have a low (3 x 10-4)increased cancer risk from this exposure. Residents who lived at 2206th Avenue and wereexposed over their entire lifetime to the maximum arsenic soil concentrations measured in theirbackyard in 1991 would have a moderate (1.3 x 10-3) increased cancer risk from this exposure. Since the facility began operating in the early 1900s and the soil was not removed from the yardin 1991, we assumed a 70-year exposure could have occurred though we are not aware if anyonehas lived at 2206 6th Avenue for that length of time. Additionally, we made an conservativeassumption that the lead levels had not changed over time.

For the purposes of evaluating potential adverse health effects to lead, lead in air was assumed to be 0.0169 µg/m3 (the highest concentration of lead measured from the three air monitoring studies)(6) and lead in water was assumed to be 5 µg/l (the concentration of lead in the water that is served by the City of Sacramento Water District to this area from the Sacramento River treatment facility)(7). At an average lead concentration of 56 ppm, the predicted blood-lead level (BLL, 99th percentile) in an adult who might have been exposed to the backyard contaminated soil before it was cleaned up is 2.9 µg/dL. At a maximum lead concentration of 222 ppm, the predicted BLL (99th percentile) is 4.0 µg/dL. The Food and Drug Administration considers the Lowest Observable Adverse Effect Level (LOAEL) for adults to be 30 µg/dL (13). Thus, before the fall of 1991 when the backyard at 2206 6th Avenue was cleaned up, adults exposed to the average or maximally-lead contaminated soil in the backyard on a daily basis were at not at risk for adverse health effects.

B. Health Outcome Data Evaluation

No complete past or current exposure pathways of concern were identified at the Union Pacificsite that would warrant an evaluation of health outcome data. Though there has been communityconcern, this community concern has not focused on health as much as exposure.

C. Community Health Concerns Evaluation

Based on the information reviewed in this health assessment, the petitioner's concerns and theconcern about cancer levels in the community being elevated can not be substantiated as beingrelated to the Union Pacific site. CDHS/ATSDR concur with those community members aboutthe need to accurately assess future health risks before a plan of development occurs.

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