PUBLIC HEALTH ASSESSMENT
ODESSA SUPER SITE
(a/k/a SPRAGUE ROAD GROUND WATER PLUME)
ECTOR, ECTOR COUNTY, TEXAS
ENVIRONMENTAL CONTAMINATION / PATHWAYS ANALYSIS /
PUBLIC HEALTH IMPLICATIONS
Exposure to, or contact with chemical contaminants drive the ATSDR public health assessment process. The release or disposal of chemical contaminants into the environment does not always result in exposure or contact; and, chemicals only have the potential to cause adverse health effects if people actually come into contact with them. People may be exposed to chemicals by breathing, eating, or drinking a substance containing the contaminant or by skin (dermal) contact with a substance containing the contaminant.
When people are exposed to chemicals, the exposure does not always result in adverse health effects. The type and severity of health effects that may occur in an individual from contact with contaminants depend on the toxicologic properties of the contaminants; how much of the contaminant to which the individual is exposed; how often and/or how long exposure is allowed to occur; the manner in which the contaminant enters or contacts the body (breathing, eating, drinking, or skin/eye contact); and the number of contaminants to which an individual is exposed (combinations of contaminants). Once exposure occurs, characteristics such as age, sex, nutritional status, genetics, life style, and health status of the exposed individual influence how the individual absorbs, distributes, metabolizes, and excretes the contaminant. These factors and characteristics influence whether exposure to a contaminant could or would result in adverse health effects.
In preparing this public health assessment, we relied on the information provided in the referenced documents. The Agency assumed that adequate quality assurance and quality control measures were followed with regard to chain-of-custody, laboratory procedures, and data reporting. The validity of the analyses and the conclusions drawn in this document are determined by the availability and reliability of the referenced information.
Groundwater and surface soil sampling data were collected at each of the three facilities to determine the extent that chromium contamination has spread off of the site. Drinking water samples and soil samples collected were reviewed and validated by EPA Region 6 according to all appropriate guidelines (the USEPA Contract Laboratory Program Statement of Work for Inorganic Analysis, Organic Analysis, and National Functional Guidelines for Organic Data Review and Inorganic Analyses).
Tables listing available environmental sampling data for each of the three facilities associated with this NPL site are available in Appendix D. The most recent groundwater sampling data for total chromium and hexavalent chromium was completed by EPA in August of 1996 (Appendix D, Table 1). During this sampling event, samples were collected from monitoring wells, residential wells, and industrial water wells in the vicinity of the three facilities. Additional groundwater data (for volatile organic compounds, semi-volatile organic compounds, and metals) are available for each of the three facilities (Appendix D, Table 2). Surface soil sampling data are presented in Appendix D, Tables 3 (Leigh Metal Plating), 4 (National Chromium Corporation), and 5 (Machine and Casting, Inc.).
Table 2 through 5 present the maximum concentrations reported for each of the contaminants
detected. ATSDR comparison values for each of the contaminants also are listed in the tables.
Comparison values are media specific contaminant concentrations used to select contaminants for
further evaluation. Inclusion of a contaminant in a table or the fact that a contaminant exceeds a
comparison value does not imply that the contaminant represents a threat to public health. A
general explanation of comparison values is provided in the box below.
|
Explanation of Comparison Values |
|
| MCL
CREG
|
The maximum permissible level of a contaminant in a public
water system.
The Cancer Risk Evaluation Guide is an estimated contaminant concentration that would result in no more than one excess cancer in a million (10E-6) persons exposed over a lifetime. CREGs are calculated from EPA's cancer slope factors (CSFs). Environmental Media Evaluation Guides are based on ATSDR's minimal risk levels (MRLs). An MRL is an estimate of a daily human exposure to a chemical that is likely to be without an appreciable risk for noncarcinogenic effects over a specified duration of exposure (acute, intermediate, chronic). Similar to the EMEG but derived from EPA's reference dose. It is the concentration in a specific media at which daily human exposure is unlikely to result in adverse noncancerous effects. The Lifetime Health Advisory represents a contaminant concentration that EPA considers to be protective of noncarcinogenic health effects during a lifetime (70 years) of exposure. A subscript child adjacent to the EMEG or RMEG indicate that the comparison value was determined using a child exposure scenario. Child EMEGs and RMEGs are lower for children. Levels reported to exist in an uncontaminated environment. In this document background represents sampling data in the northwest Odessa area. |
| Table 1 - Health Hazard Situation-Sprague Road Groundwater Plume Site | ||||||||
| PATHWAY NAME |
PRIMARY CONTAMINANTS OF CONCERN |
EXPOSURE PATHWAYS ELEMENTS | TIME | COMMENTS | ||||
| SOURCE | ENVIRONMENTAL MEDIA |
POINT OF EXPOSURE |
ROUTE OF EXPOSURE |
EXPOSED POPULATION |
||||
| Groundwater |
Chromium
|
Leigh Metal Plating | Groundwater
|
Off-site residences
|
Ingestion
|
Local area residents using well water for
domestic purposes. People who used to work at Leigh Metal, National Chromium, and Machine and Casting.
|
Past Present Future
|
In the past, workers and local residents used groundwater from the vicinity of these facilities for potable and other domestic purposes. The majority of the people have been switched to city water; however, at least one resident and possibly others still use the water. We estimate the current exposed population to be less than 10 persons. Additional people could be at risk for exposure to the contaminated groundwater if the existing groundwater contamination is not remediated. |
| National Chromium Corporation | ||||||||
| Machine and Casting, Inc. | ||||||||
| Surface Soil
|
Chromium
|
Leigh Metal Plating | Surface Soil | On-site | Ingestion Inhalation Dermal contact
|
Trespassers On-site workers
|
Past Present Future
|
In the past workers on the site may have been exposed to chromium contaminated soil. An unknown number of trespassers on these sites also may be exposed to contaminated soil. |
| National Chromium Corporation | On-site | |||||||
In this section we evaluated the possible pathways for exposure to contamination at Sprague Road Groundwater Plume site. We examined these possible exposure pathways to determine whether people in the community can be exposed to (or come into contact with) contaminants from the site. Exposure pathways consist of five elements; 1) a source of contamination, 2) transport through an environmental medium, 3) a point of exposure, 4) a plausible manner (route) for the contaminant to get into the body, and 5) an identifiable exposed population. Exposure pathways can be complete, potential, or eliminated. For a person to be exposed to a contaminant, the exposure pathway must be complete. An exposure pathway is considered completed when all five elements in the pathway are present and exposure has occurred, is occurring, or will plausibly occur in the future. A potential pathway is missing at least one of the five elements but may possibly be complete in the future as more data become available or site conditions change. Eliminated pathways are missing one of more of the five elements and will never be complete. The exposure pathways considered in our evaluation of this site are summarized in Table 1
Evaluation of Possible Groundwater Exposure Pathways
Summary: As a result of our site visit observations, and a review of the available data, we concluded that chromium in the groundwater presents a public health hazard. In the past, on-site workers and local residents used contaminated groundwater for drinking and other domestic purposes. At present, we have identified at least one residence that continues to use the groundwater as a source of drinking water. In the absence of remediation the groundwater plume could extend towards other residences where groundwater continues to be a source of drinking water. A review of the groundwater pathway considered in this assessment is presented below.
The major hydrologic units which contain potable water in the vicinity of the Sprague Road Groundwater Plume NPL site are the Ogallala Formation and the Trinity Sand. In general the Ogallala is hydrologically connected with the underlying Trinity but has little saturated thickness. Water in the Ogallala Aquifer flows to the south and southeast, except in areas where there is heavy pumping of the wells, then the direction of flow is toward the area of withdrawal. Generally, the depth to the water table is about 85 feet below the ground surface and the base of this aquifer is about 145 feet below ground surface. Within the site area, the Ogallala Aquifer has a saturated thickness of 60 feet [4]. The hydraulic characteristics of the Ogallala are more important than the amount of water it holds since it may potentially act as a medium through which contaminants may enter the underlying Trinity aquifer. The Trinity sand underlying the Ogallala is the major aquifer in the vicinity of this NPL site. Up to 70 feet of saturation may be present in these sands, sandstones, and gravel. The city of Odessa has wells which penetrate the entire Trinity section. These wells average a yield of 167 gallons per minute.
Until September 1993 numerous business and residences all were on individual private water wells (Appendix C). Following discovery of chromium in residential and individual wells at concentrations above the MCL, the City/County extended water service to the area affected by the chromium plume; however, some residents still obtain water from individual wells. The TNRCC and the EPA have done extensive work to identify water well use in the vicinity of the site and the extent of chromium contamination at levels above the MCL. In addition, the city closed some public water supply wells within 4 miles of the site in response to low water output and concern about the chromium problem.
The City of Odessa receives its public water supply from combined surface and groundwater sources. On a yearly average, surface water supply from Lake O.H. Ivie provides approximately 90 percent of the total water volume. The rest is provided by groundwater. The twenty-five active public supply wells which supply this groundwater all are within four miles of the Sprague Road Groundwater Plume Site.
Bis(2-ethylhexyl)phthalate (BEHP), 1,2-dichloroethane (1,2-DCA), and 1,1-dichloroethene (1,1-DCE) all were detected in groundwater at maximum concentrations above their respective comparison values. BEHP was detected above its CREG in groundwater below LMP and M&C; 1,2-DCA was detected above its CREG in groundwater below LMP; and 1,1-DCE was detected above its CREG in groundwater below NCC . Although these contaminants were detected at concentrations above their respective CREGs, based on EPA's substance specific cancer potency values and a maximum exposure scenario (drinking two-liters of water per day for 70 years) we would estimate there to be no apparent increased lifetime risk for cancer associated with these contaminants.
Chromium was the main contaminant detected in groundwater at concentrations of potential public health concern. The highest reported concentration of chromium (17.4 mg/L ) was measured in groundwater from an on-site monitoring well on the National Chromium site during the August 1996 EPA sampling event. Concentrations of chromium above EPA's MCL (0.1 mg/L) were measured in 19 of the water wells sampled (Appendix D, Table 1; Appendix B, Figure 2b).
Chromium exists in the environment primarily in two forms. Trivalent chromium (chromium [III]) occurs naturally in the environment and is an essential nutrient that helps the body use sugar, protein, and fat. An intake of 50 to 200 micrograms (µg) per day is recommended for adults. Hexavalent chromium (chromium [VI]) generally comes from industrial processes. Based on EPA's reference dose(RfD) of 0.005 mg/kg/day, chromium [VI] is about 200 times more toxic than chromium [III]; however, confidence in the RfD is low, because it is based on an animal study in which there was a lack of toxic effect even at the highest dose. The reference dose for chromium [VI] was derived by dividing the highest observed NOAEL (2.4 mg-Cr[VI]/kg/day for one year) by an uncertainty factor of 500.
Ingesting a small amount of chromium [VI] generally is not harmful; however, accidental or intentional ingestion of large amounts can cause upset stomach, ulcers, kidney and liver damage, and even death. Ingestion of chromium has not been shown to cause cancer, although inhalation of chromium [VI] has been demonstrated to cause lung cancer. Dermal exposure to chromium can cause skin rashes in sensitive persons [8]. For acute exposure in humans LOAELs for serious effects (gastrointestinal, hepatic, renal, and death) range from approximately 4.1 to 29 mg/kg/day. Many of these effects were reported after a single dose. Less serious effects (enhancement of dermatitis) have been reported after acute exposure to doses as low as 0.036 mg/kg/day. For chronic-duration exposure an oral LOAEL for gastrointestinal and hematological effects of 0.57 mg/kg/day has been reported for humans [8]. If an adult were to drink water containing 17.4 mg chromium/L (the highest concentration measured at this site) that person would be exposed to just slightly less than the concentration which is known to cause gastrointestinal and hematological effects; a child would be exposed to more than 0.57 mg/kg/day.
Much of the data provided did not specify the type of chromium detected; however, during the August 1996 sampling event both total chromium and hexavalent chromium were measured and in most instances hexavalent chromium accounted for over 90 percent of the total chromium. In the interest of protecting public health, when not specified, we assumed the reported concentrations to be chromium [VI].
At this site, at least two households continue to use well water for drinking and other household purposes even though they are aware that the chromium concentrations exceed the maximum contaminant level of 0.1 mg/L. The measured concentration of chromium in one of the households was 0.3 mg/L; the concentration of chromium measured in August 1996 in the other household was 0.358 mg/L. The concentration of 0.3 mg/L is equal to a dose of 0.02 mg/kg/day. This is four times greater than the reference dose of 0.005 mg/kg/day. One household immediately south of the National Chromium plume is using one well for drinking and other household uses; in August of 1996, the concentration of chromium in this well that was 0.049 mg/L. A second well, not currently supplying the household with drinking water had a chromium concentration of 0.165 mg/L. The resident had considered connecting the second well to the first; however, EPA recommended against this until the chromium concentration in the groundwater was reduced.
Accidental or intentional swallowing of large amounts of chromium (VI) can cause stomach upsets, ulcers, convulsions, kidney and liver damage, and even death. In a cross sectional study conducted in 1965 of 155 people whose well water contained 20 mg chromium (VI)/L (pollution from an alloy plant in the People's Republic of China), associations were found between drinking the contaminated water and oral ulcer, diarrhea, abdominal pain, indigestion, and vomiting, leukocytosis and immature neutrophils. The 20 mg chromium (VI)/L concentration was estimated to be equivalent to a dose of 0.57 mg chromium (VI)/ kg body weight/ day.
Liver damage, evidenced by jaundice, increased bilirubin, and increased serum lactic dehydrogenase, were described from cases of people ingesting chromium (VI) compounds. Acute renal failure, characterized by proteinuria, hematuria, followed by anuria also has been reported. An expert panel recently concluded that chromium concentrations below 35 mg/L in water are not likely to cause dermatitis.
Based on the maximum concentration of chromium identified in the groundwater (17.4 mg/L), it would be possible for a person drinking this water to exceed the dose associated with gastrointestinal effects ([17.4 mg/L * 1¼ L/day] ÷ 35 kg-BW) and based on the concentrations reported in wells currently used for drinking water, the reference dose could be exceeded both by children and adults. At this time, groundwater contamination associated with the Sprague Road Groundwater Plume site presents a public health hazard.
Evaluation of Possible Soil Exposure Pathways
Summary: As a result of our site visit observations, and a review of the available data, we concluded that contaminated soil associated at LMP presents a potential public health hazard. Chromium levels in the soil are high and there is evidence of trespassing on the site; however, we could not determine with any degree of certainty whether people were frequenting the contaminated area. A review of the soil pathway considered in this assessment is presented below.
On-site and offsite surface soil (0-4 inches) were collected from each of the facilities associated with the Sprague Road Groundwater Plume site. Samples were analyzed for volatile organic compounds, semi-volatile organic compounds, pesticides, and metals. Although several contaminants were reported at concentrations above their respective CREGs, we would not expect exposure to these compounds at the reported concentrations to result an a significant increased lifetime risk for cancer. In 1995 at NCC, lead was detected at a maximum concentration of 1,300 mg/kg east of the building. While 1,300 mg/kg exceeds the comparison value for this contaminant, exposure possible to soil at this site would be infrequent and would not be likely to present a threat to public health. In addition, the EPA removed more than 2,600 tons of contaminated soil from NCC in 1996.
Chromium was detected at concentrations well above the chromium (VI) noncarcinogenic comparison value both at LMP (36,500 mg/kg) and NCC (42,400); however, in 1996, the EPA removed approximately 2,600 tons of contaminated soil from NCC. We are not aware of any removal actions at LMP. In most soils chromium is present in the chromium (III) state; however, since speciation was not available we assumed the chromium at this site to be the more toxic chromium (VI). There was evidence of trespassing at LMP; thus, access to the contaminated areas by trespassers is possible. Although in a typical trespasser scenario, contact with the soil would be short-term and infrequent, we estimate that a 35 kg child (approximately 12 years old) ingesting as little as 35 milligrams of soil per week would exceed the reference dose. Of course this estimate is based on an exposure point concentration of 36,500 mg/kg a single point value; the actual exposure point concentration most likely is lower.
On-site air data were not available for our review; although windblown soils may have been a
concern in the past when contaminated soils were piled up at Leigh Metal Plating. The August
1995 Site Screening Inspection (SSI) Report for Leigh Metal Plating reported that although air
samples were not taken at the site, results of surface soil samples collected from the site (1995)
were used to assess potential for releases to occur to air [5]. This SSI also states that there are no
known observed releases of hazardous substances to the air from Leigh Metal Plating [5].
COMMUNITY HEALTH CONCERNS/CHILD HEALTH INITIATIVE/
HEALTH OUTCOME DATA
In an attempt to collect community health concerns related to the Sprague Road Groundwater Plume site, we contacted several different agencies and individuals by telephone, including the regional offices of both the Texas Department of Health (TDH Region 9) and the Texas Natural Resource Conservation Commission. In addition to state agencies we contacted local health department staff and local citizens. EPA and the Texas Department of Health held two Open House meetings for community members in March and July of 1998. Approximately 15 people attended each of the meetings. Community concerns were compiled from those attending the meetings and from those individuals we spoke with while going door to door in the neighborhood. We received the following health concerns. Several concerns were received pertaining to the Odessa Drum site; these concerns will be addressed as a separate health consultation.
If your water has been tested for chromium concentration and it is below the maximum contaminant level of 0.1 milligrams chromium per liter of water, it should be safe to drink with respect to the chromium concentration. If your water has not been tested and you live close to the contaminated areas (see figure 2b), you should have your water tested.
Generally root crops may take up some chromium from highly contaminated soils; however, most of the chromium is retained in the roots with only a fraction moving to the above parts of edible plants. Thus, based on available information, leafy vegetables and above ground fruits and vegetables are not likely to take up chromium in concentrations that would cause health problems to people eating those fruits and vegetables.
Although the only way to definitively answer this question would be to have your vegetables tested, based on available information it does not appear likely that leafy vegetables and above ground fruits and vegetables will take up chromium from the soil in sufficient quantities to cause health problems.
Irrigating soil with water contaminated with chromium can
cause chromium to be added to the soil. The amount of chromium that accumulates
in the soil depends upon several factors: 1) the concentration of chromium
in the water, 2) how often the water is added, 3) how much water is used
during each watering cycle, 4) the size of the area over which the water
is added, and 5) how deeply the water penetrates into the soil (the deeper
the penetration the lower the accumulated concentration). The public health
implications of chromium added to the soil depend upon the concentration
of the chromium in the soil, the type of chromium (III or VI), and the amount
of that soil that you ingest. Using the following assumptions:
| Weight of soil | = 35 kg per cubic foot |
|
Area watered |
= 100 square feet |
|
Penetration |
= 1 foot |
|
Frequency of watering |
= 3 times per week 50 weeks per year |
|
Amount of water per event |
= 100 gallons |
|
Chromium conc. in water |
= 300 µg/L (0.3 mg/L) |
|
Type of chromium |
= (VI) |
We estimate that it would take over 60 years for the chromium concentration in the soil to exceed the soil screening value for children. It would take over 800 years to exceed the soil screening level for adults. If all of the above conditions were the same, but the chromium concentration in the water was 0.9 mg/L, then we estimate that it would take 20 years for the chromium concentration in the soil to exceed the screening value for children. It would take 267 years to exceed the soil screening level for adults.
Short-term exposure to large amounts of chromium through ingestion has caused kidney damage both in humans and animals; however, long-term exposure to low levels of chromium has not. Based on the maximum values reported in the groundwater, it is not likely that the chromium in the water would effect your kidney; however, we cannot say this with absolute certainty. Long-term exposure to other metals such as cadmium can result in kidney toxicity and smoking is a significant source of cadmium.
Chromium has not been associated with breast cancer; other risks factors such as high fat diets have.
Exposure to chromium (VI) compounds has been reported to affect the blood of humans. Blood effects were not observed in rats fed varying amounts of chromium in their diets. At this time it would be difficult if not impossible to determine if exposure to chromium was responsible for the dogs' past illnesses.
Not likely. In fact, a deficiency of chromium (III) in the diet can impair the body's ability to use sugars and other nutrients properly and could lead to a diabetic like condition. Exposure to chromium (VI) has not been associated with diabetes.
Not likely. Although air data were not available, based on available information it does not appear that air levels would be sufficient to cause adverse health conditions.
ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants and children demand special emphasis in communities faced with contamination of their water, soil, air, or food. Children are at greater risk than adults from certain kinds of exposures to hazardous substances emitted from waste sites and emergency events. They are more likely to be exposed because they play outdoors and they often bring food into contaminated areas. They are shorter than adults, which means they breathe dust, soil, and heavy vapors close to the ground. Children are also smaller, resulting in higher doses of chemical exposure per body weight. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Most importantly, children depend completely on adults for risk identification and management decisions, housing decision, and access to medical care.
ATSDR evaluated the likelihood for children living in the vicinity of the Sprague Road Groundwater Plume site to be exposed to site contaminants at levels of health concern. ATSDR identified situations in the past in which children were likely to have been exposed to chromium contamination in groundwater. Children currently are not likely to be exposed to chromium in groundwater unless the extent of the contamination spreads to water wells which are being used by families with children. The maximum reported concentration of chromium in soil at LMP was very high and access to the site by children is possible. If children were to frequently trespass on this site they could be at risk. The five foot pit on the National Chromium Corporation site presents a physical hazard to small children who may trespass on the site.
Health outcome data (HOD) record certain health conditions that occur in populations. These data can provide information on the general health of communities living near a hazardous waste site. It also can provide information on patterns of specified health conditions. Some examples of health outcome databases are tumor registries, birth defects registries, and vital statistics. Information from local hospitals and other health care providers also may be used to investigate patterns of disease in a specific population. Other than routinely collected birth and death data, no additional information pertaining to health outcome data for residents living in the vicinity of the site was available.
We checked the Bureau of Epidemiology files, Health Studies Program Files and checked with both the local and regional public health departments. No special studies have been conducted other than the collection of routine birth and death records.
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