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1. ATSDR > Public Health Assessments & Consultations

PRELIMINARY PUBLIC HEALTH ASSESSMENT

U.S. SMELTER AND LEAD REFINERY, INC.
(a/k/a USS LEAD REFINERY INC.)
EAST CHICAGO, LAKE COUNTY, INDIANA

ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

The tables in this section list the contaminants of concern. The contaminants will be evaluated in subsequent sections of this preliminary public health assessment to determine whether exposure to them has public health significance. ATSDR selects and discusses contaminants using the following information:

1. Concentrations of contaminants on- and off-site.

2. Field data quality, laboratory data quality, and sample design.

3. Comparison of on-site and off-site concentrations with comparison values for both cancerous and non-cancerous effects.

4. Community health concerns.

In the data tables that follow under both On-Site and Off-Site Contamination, the presence of a listed contaminant does not necessarily indicate that it will cause adverse health effects. Instead, the list indicates contaminants that will be evaluated further in this preliminary public health assessment.

ATSDR uses comparison values -- contaminant concentrations in specific media that are considered protective of public health -- to select contaminants for further evaluation. ATSDR and other agencies have developed the comparison values to provide guidelines for estimating contaminant concentrations in media at which adverse health effects are not expected to occur. A standard daily ingestion rate and body weight are assumed in deriving these values. The following comparison values are used in this section:

CREG	=	Cancer Risk Evaluation Guide: Derived by ATSDR from the EPA cancer slope factor. It represents a concentration in water, soil, or air at which excess cancer risk is not likely to exceed one case of cancer in a million persons exposed over a lifetime.
EMEG	=	Environmental Media Evaluation Guide: Derived by ATSDR from ATSDR's minimal risk level (MRL). It is the concentration in water, soil, or air at which daily human exposure is unlikely to result in adverse noncancerous effects
RMEG	=	Reference Media Evaluation Guide: Derived by ATSDR from the EPA oral reference dose. It is the concentration in water or soil at which daily human exposure is unlikely to result in adverse noncancerous effects.
PMCLG	=	Proposed Maximum Contaminant Level Goal: Non-enforceable drinking water health goal recommended by EPA and set at a level at which no known or anticipated adverse human health effects are expected.

In addition, should no CREG be available for substances which may be carcinogenic (may cause cancer), these substances are included as contaminants of concern regardless of the observed concentrations.

The EPA maintains the Toxic Chemical Release Inventory (TRI), a database of over 320 different toxic substances released from facilities into the environment. Because USS Lead ceased operations in 1985, the TRI was searched for information about releases that may have occurred up to and including 1987 in the area surrounding USS Lead. A large amount of metals were reportedly released into both air and water. Lead, manganese, and aluminum oxide were released in large amounts into the air (22,000 pounds, 18,000 pounds, and 48,000 pounds, respectively). Additional metals listed as air emissions were aluminum (1,400 pounds), antimony (250 pounds), and chromium (742 pounds). Water emissions listed were lead (2,050 pounds), zinc (1,000 pounds), and chromium (750 pounds).

A. On-Site Contamination

Waste Material

Waste materials which have been sorted on-site are:

1)	Calcium sulfate (CaSO4) sludge generated from neutralizing battery acids. The sludge was dried and stored in piles on the southern portion of the site. The sludge was contaminated with arsenic, cadmium, and lead. It was removed from the site in June 1992.
2)	Baghouse flue-dust generated by the blast furnace. Dust from the furnace exhaust was collected by passing the exhaust through fabric bags, which acted as filters. Dust from these bags was collected for recycling into the smelter. The dust contained large amounts of lead, arsenic, and antimony, and lesser amounts of cadmium and antimony. Up to 8,000 tons of the dust was stockpiled on-site. In 1982, the dust, which had been stored over a three to five acre area, was brought under cover in the Tank House building to prevent dispersion by wind and rain. The dust was removed from the site in June 1992.
3)	Slag generated from the blast furnace. The blast furnace slag has been disposed of primarily in the southern area of the site. The slag was used as fill in the wetlands. It is contaminated with lead.
4)	Baghouse bags. The bags which were used to catch the flue-dust were emptied and stored on-site in large piles. These bags are believed to be contaminated with lead.

Limited sampling has been completed on some of these wastes. Maximum observed concentrations are listed in table 1.

Table 1. On-site waste contaminants of concern

Surface Soil and Sediment

A few soil and sediment samples have been taken to confirm contamination at the site. Surface soil (0 to 1 inch deep) samples from various on-site locations indicate widespread contamination by lead, arsenic, and antimony. Sediment samples from the marsh which receives some of the stormwater run-off from the site indicate that marsh sediments are contaminated with lead, arsenic, antimony, and some mercury. Additional soil contamination occurs near the canal, where oil storage tanks were kept. Although no documentation could be found regarding fuel oil contamination in the area, visible contamination is present.

Table 2. On-site soil and sediment contaminants of concern

Surface Water

On-site surface water has become heavily contaminated with metals and fuel oils. A stormwater outfall discharges into a canal, which flows directly into the Grand Calumet River. A few grab samples and ten months of continuous monitoring during plant operations in 1984 indicate that the discharge has been contaminated with lead, arsenic, and several other metals, as well as fluoride and sulfate. In addition, a black oily layer was observed on top of the canal water near the outfall discharge. This area is near the oil storage tank locations. The canal water has become contaminated with similar metals as were observed in the discharge, but at lower concentrations. A marsh receives additional stormwater run-off from the site. Surface water collected from the marsh also contained contaminants similar to those observed in the outfall discharge.

Table 3. On-site surface water contaminants of concern

Ambient Air

Large amounts of lead-contaminated dust have been released in the past during normal operations of the smelter. The Indiana State Board of Health conducted air monitoring on-site in 1985, and found high levels of fugitive dust and lead suspended in the air. In addition, the practice of storing baghouse flue-dust in open-air piles allowed dispersal of the dust. This practice ended in 1982, when the dust was moved into the Tank House. No air monitoring data is available for the period previous to 1982.

Table 4. On-site ambient air contaminants of concern

B. Off-site Contamination

Surface Soil

Surface soils were sampled for lead in 1985 at several locations off-site by the Indiana Air Pollution Control Board. The sampling was done to confirm the presence of lead. The number of samples at each location were not sufficient for characterization of the off-site areas. Since the source of the lead contamination was most likely the deposition of flue-dust particulates out of the air, then additional contaminants found in the flue-dust may also be present in off-site surface soils. Surface soils at the E.C. DuPont facility, which is directly across Kennedy Avenue from USS Lead, contained extremely high amounts of lead. Several other off-site locations in residential areas contained high levels of lead contamination in surface soils, including the E.C. Rehabilitation Center (now the Lake County Rehabilitation Center), a playground, a schoolyard, and an area at the intersection of Melville and 151st Street. Concentrations tended to decrease rapidly with increasing distance from the site.

Table 5. Off-site surface soil contaminants of concern

Sediment

Sampling data for three sediment samples taken from the Grand Calumet River were found in the US EPA's STORET database and presented in a site assessment plan for USS Lead [5]. This data provides only a limited amount of information, indicating that there are several lead sources which may be affecting the river. The upstream lead concentration is 350 ppm, which is relatively high. Lead concentrations at the mouth of the canal as it exits USS Lead are much higher, at 1,177 ppm. However, the nearby sewage treatment plant also discharges large quantities of lead, and sediments found near its discharge location were 4,758 ppm.

Table 6. Off-site sediment contaminants of concern

Contaminant	Location	Maximum Concentration (ppm)	Date and Reference	Comparison Value
				ppm	Source
Lead	Grand Calumet River, upstream	350	unknown [11]	none	carcinogen
	Near discharge, sewage treatment plant	4,758
	Canal mouth	1,177

Surface Water

During a preliminary site sampling study of USS Lead, water samples were taken from the Grand Calumet River, both upstream and downstream of the canal exiting the site. Aluminum, boron, lead, and manganese were present in both samples. There was no increase in the amount of metal contamination observed in the downstream sample compared to the upstream sample. However, single sampling events for surface water are not conclusive.

Table 7. Off-site surface water contaminants of concern in the Grand Calumet River

Contaminant	Maximum Concentration (ppb)		Date and Reference	Comparison Value
	Upstream	Downstream		ppb	Source
Aluminum	300	150	4/81 [5]	none
Boron	90	80	4/81 [5]	100	RMEG
Lead	40	40	4/81 [5]	none	carcinogen
Manganese	120	120	8/81 [5]	50	RMEG

Ambient Air

Air monitoring for lead in off-site ambient air was conducted from 1985 through 1989 by the Indiana Department of Environmental Management. Air monitoring stations were placed at several locations, including E.C. DuPont, the E.C. Rehabilitation Center, the East Chicago Post Office, and a location at 2401 Michigan Avenue. Data collected at three of these locations in 1985, when the smelter was in operation, indicate that concentrations of airborne lead were relatively high, at an average of 16.1 µg/m³ at E.C. DuPont, and 1.3 µg/m³ at the E.C. Rehab Center and the East Chicago Post Office. Subsequent sampling in 1986 through 1989 indicate that the concentrations of airborne lead quickly decreased after the smelter ceased operations. Lead concentrations averaged 0.12 to 0.46 µg/m³ in this time period.

Table 8. Off-site ambient air contaminants of concern

C. Quality Assurance and Quality Control

In preparing this preliminary public health assessment, ATSDR relies on the information provided in the referenced documents. The Agency assumes 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 analysis and conclusions drawn for this preliminary public health assessment is determined by the reliability of the referenced information.

D. Physical and Other Hazards

Several physical hazards were noted during the ATSDR site visit. Buildings on the site have become dilapidated and unsafe through lack of maintenance and acts of vandals. Until 1991, access to the site was unrestricted, and vandals frequently trespassed into the area. Although the electrical power to USS Lead has been shut off, a transformer at the facility remains active. One trespasser was electrocuted several years ago after apparently assuming that the transformer was no longer live.

PATHWAYS ANALYSES

To determine whether nearby residents and workers are exposed to contaminants migrating from the site, ATSDR evaluates the environmental and human components that lead to human exposure. This pathway analysis consists of five elements: A source of contamination, transport through an environmental medium, a point of exposure, a route of human exposure, and an exposed individual or population.

ATSDR categorizes an exposure pathway as a completed or potential pathway if it cannot be eliminated. Completed pathways require that the five elements exist and indicate that exposure to a contaminant has occurred in the past, is currently occurring, or will occur in the future. Potential pathways, however, require that at least one of the five elements is missing, but could exist. Potential pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future. Eliminated pathways require that at least one of the five elements is missing and will never be present. Table 9 identifies the completed exposure pathways. Table 10 estimates the number of exposed persons for completed exposure pathways and the number of potentially exposed persons for potential exposure pathways. The discussion that follows incorporates only those pathways that are important and relevant to the site.

A. Completed Exposure Pathways

Surface Soil and Waste Pathways

Surface soils have become heavily contaminated with metals, both on-site and off-site. When USS Lead was in production, its workers were exposed to elevated levels of lead, arsenic, and other metals in surface soils and wastes stored on-site. After production at USS Lead ceased in 1985, trespassers began entering the facility to remove building materials and scrap. These trespassers were also exposed to the contaminated soils and wastes. Extremely high levels of lead were found in surface soils at the E.C. DuPont facility adjacent to USS Lead. This lead contamination was most likely deposited from past ambient air contamination emanating from USS Lead. Workers at the DuPont plant are exposed to lead-contaminated soils. Additional sampling in a nearby residential area indicates that the lead contamination extends for a distance of at least 3,000 feet (over half a mile) to the north. Residents in this area have been exposed to soil contaminated with lead and possible the other contaminants found in the flue-dust on-site. Exposure to the lead occurs through incidental ingestion of and dermal contact with soils and wastes. Adults and especially children swallow small amounts of lead-contaminated soil because of hand to mouth activity. In addition, small children occasionally develop pica behavior, meaning that they swallow non-food items, such as large amounts of soil. Pica behavior would greatly increase the amount of lead exposure experienced by a child.

Ambient Air Pathways

Air sampling data indicates that lead-contaminated dusts contaminated ambient air, both on- and off-site. Concentrations were highest on-site, and decreased with increasing distance from the site. The highest documented concentrations occurred in 1985, when the site was in operation. After this time, the concentrations decreased dramatically. Prior to 1982, the practice of storing baghouse flue-dust in open-air piles allowed dispersal of the dust into the air. This would have tended to increase lead concentrations in the air until the piles were stored in the Tank House. The air sampling efforts focused on lead contamination. However, since most of this contamination probably came from particulates which escaped the baghouse, its constituents should be very similar, indicating that additional metals, such as arsenic and cadmium, were also present in the air at high concentrations. Workers at USS Lead while in operation experienced the greatest exposures to lead. Off-site workers at E.C. DuPont also were exposed to very high levels of lead in the ambient air. The limited information available for non-industrial off-site areas indicate that ambient air at these areas was also contaminated by lead. Exposure to the lead-contaminated dusts occurs through inhalation.

B. Potential Exposure Pathways

No potential exposure pathways were found at USS Lead.

C. Eliminated Exposure Pathways

Public Supply Well Pathways

The Grand Calumet River flows into Lake Michigan through the Indiana Harbor. Lake Michigan provides water to several municipal water supplies. These water distribution centers, however, are required to periodically sample water for several substances, including the contaminants of concern related to USS Lead. Should these contaminants be found at levels above the US EPA, Illinois, or Indiana regulatory values, the surface water source would be removed as a water source. For this reason, the pathway for exposure through public supply wells is eliminated.

Biota (Food Chain) Pathways

Two possible pathways were considered for exposure through biota, or foods. Surface water and sediments in the USS Canal and the Grand Calumet River have become contaminated with metals from USS Lead. These contaminants have some potential for bioconcentration within fish. However, since the community of East Chicago is a heavily industrial area, there is no fishing of the Grand Calumet River, or Indiana Harbor, into which the river flows. Therefore, this pathway was eliminated. An additional possibility for exposure through the food-chain is the through the consumption of vegetables and fruits which have been grown in contaminated soils. There was no evidence, however, that residents in the area kept vegetable gardens.

Table 9. Completed Exposure Pathways

Table 10. Estimated Population for Completed Exposure Pathways

Exposed Populations		Media	Contaminants
Location	Estimated Persons
On-site workers and trespassers	100	surface soil, waste	antimony, arsenic, cadmium, chromium, lead, manganese, mercury, selenium, tungsten, yttrium
Off-site workers and residents	10,000		lead
On-site workers and trespassers	100	ambient air	lead
Off-site workers and residents	10,000

PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

Introduction

The contaminants of concern released into the environment at USS Lead have the potential to cause adverse health effects. However, for adverse health effects to occur the pathway for exposure must be completed. A release does not always result in exposure. A person can only be exposed to a chemical if they come in contact with the chemical. Exposure may occur by breathing, eating, or drinking a substance containing the contaminant or by skin (dermal) contact with a substance containing the contaminant.

Several factors determine the type and severity of health effects that occur from an exposure to a contaminant. Such factors include the exposure concentration (how much), the frequency and/or duration of exposure (how long), the route or pathway of exposure (breathing, eating, drinking, or skin contact), and the multiplicity of exposure (combination 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. Together those factors and characteristics determine the health effects that may occur as a result of exposure to a contaminant.

ATSDR considers the above physical and biological characteristics when developing health guidelines. Toxicological profiles prepared by ATSDR summarize chemical specific toxicological and adverse health effects information. Health guidelines such as ATSDR's Minimal Risk Level (MRL) and EPA's Reference Dose (RfD) and Cancer Slope Factor (CSF) are included in the toxicological profiles. Those health guidelines are used by ATSDR health professionals in determining the potential for developing adverse noncarcinogenic health effects and/or cancer from exposure to a hazardous substance.

A Minimal Risk Level (MRL) provides a basis for comparison with concentrations of contaminants in different environmental medium (soil, air, water, and food) to which people might be exposed. If daily exposure occurs at an amount below the MRL, harmful noncancerous health effects are not expected to occur. If daily exposure exceeds the MRL, then ATSDR evaluates whether or not that level of exposure is likely to cause adverse health effects by comparing the amount of exposure to levels in animal and human studies. The method for deriving MRLs does not include information about cancer, therefore, an MRL does not imply anything about the presence, absence, or level of cancer risk. An EPA Reference Dose is an estimate of the daily exposure for the human population, including sensitive sub-populations, that is likely to be without appreciable risk of adverse noncarcinogenic health effects during a lifetime (70 years). The RfD is a health guideline for the oral route of exposure. For carcinogenic substances, EPA has established the Cancer Slope Factor (CSF) as a health guideline. The CSF is used to determine the number of excess cancers expected from exposure to a contaminant.

To link the site's human exposure potential with health effects that may occur under site-specific conditions, ATSDR estimates human exposure to the site contaminant from ingestion and/or inhalation of different environmental media [14]. The exposure dose is related to the contaminant concentration, the person's intake rate (for example, soil a person accidentally swallows), and that person's body weight.

ATSDR uses standard intake rates for ingestion of water and soil. The intake rate for incidental ingestion of soil is 100 mg/day for adults, 200 mg/day for children, and 5000 mg/day for children with pica behavior, or the swallowing of non-food items such as soil. Standard body weights for adults and children are 70 kg and 10 kg, respectively. The maximum contaminant concentration detected at a site for a specific medium is commonly used to determine the estimated exposure. Use of the maximum concentration detected in a specific medium will result in the most protective evaluation for human health. When unknown the biological absorption from the environmental medium (soil, water) is assumed to be 100%.

Antimony

Human exposure to antimony at USS Lead occurred through incidental ingestion of and dermal contact with contaminated surface soils and wastes, and potentially through inhalation of contaminated air. Exposure occurred to on-site workers and trespassers and may have occurred to off-site workers and residents.

The general population is exposed to low levels of antimony in ambient air and food. The average daily intake from ingestion of food and water has been estimated to be 5 - 100 µg/day [15]. The ingested dose which is estimated for workers at USS Lead is 480 µg/day. This dosage is 16 times higher than the US EPA's RfD. Non-cancerous adverse health effects may occur from exposure to antimony at the site through the incidental ingestion of soil.

Antimony and its compounds are currently used to treat two parasitic diseases, schistosomiasis and leishmaniasis. Toxic side effects in humans following injection with antimony-containing drugs have been reported. These effects include altered EKG, anemia, vomiting, diarrhea, joint and muscle pain, and death. Altered EKG readings were observed after 4 days of trivalent antimony treatment at a dosage over 100 times higher than that estimated for workers at USS Lead. However, for pentavalent antimony, a change in readings was not observed until after 3 weeks of injections at a dosage 1000 times higher than that for USS Lead workers [15]. Amounts as low as 80 times the USS Lead dose have resulted in vomiting. In animal experiments, amounts as low as 40 times the estimated USS Lead dose caused a minor effect on blood vessels and the cardiovascular system. There is evidence that exposure to antimony might increase the severity of existing lung or cardiovascular disease. Dermal exposure to antimony has resulted in no reported effects in humans.

No information on the carcinogenic potential of antimony in humans was found. However, antimony has not produced cancer in rats or mice exposed by the oral route.

Arsenic

Human exposure to arsenic at USS Lead occurred through incidental ingestion of and dermal contact with contaminated surface soils and wastes, and potentially through inhalation of contaminated air. Exposure occurred to on-site workers and trespassers and may have occurred to off-site workers and residents.

Arsenic is a naturally occurring element that is normally found combined with other elements. The exact forms of arsenic at USS Lead are unknown. Arsenic toxicity varies depending upon its form. The soluble inorganic forms are well absorbed from the digestive tract and distributed widely throughout the body. Arsenic is cleared rapidly from the blood. Most arsenic that is absorbed into the body is converted to a less toxic form and excreted; consequently, arsenic does not accumulate in the body during exposures to low levels. Although arsenic may concentrated in small amounts in the liver, kidney, lung, spleen, aorta, and upper gastrointestinal tract, it is also rapidly cleared from these tissues. Arsenic which remains and accumulates in the body is stored mainly in the skin and hair.

Studies of the chronic oral effects of arsenic show that although some people can ingest up to 150 µg/kg/day (microgram of arsenic per kilogram of body weight every day) without noticeable ill-effects, doses as low as 20 to 60 µg/kg/day may result in one or more signs of arsenic toxicity in more sensitive individuals. EPA's RfD for arsenic is 0.4 µg/kg/day. Adverse health effects from arsenic exposure include: digestive tract irritation, disturbances of the blood and nervous systems, skin and blood vessel injuries, and liver or kidney injury. The severity of these symptoms generally depends upon the duration of exposure. In most cases of chronic (many years) exposure, many or all of the signs of arsenic toxicity are detected together, indicating that the dose-response relationships for the various systemic end points are fairly similar. The most sensitive effects are the changes in pigmentation of the skin and the appearance of calluses. The incidental ingestion of soil and wastes containing the maximum levels detected on-site results in exposures which exceed the RfD by a factor of nine. The doses at which health effects have been noted are not exceeded. People exposed to similar levels as are estimated for workers at this site did not experience adverse effects. However, the estimated exposure in workers is about 10 times less than levels that cause blackfoot and Raynaud's diseases in humans. Some uncertainty exists in estimating the amount of worker exposure, since contaminant concentration may have been higher or lower. Workers also may have received additional exposures from breathing arsenic-contaminated dust. The total arsenic exposure, therefore, may be high enough to cause blackfoot and Raynaud's diseases and skin discoloration.

People who may show increased sensitivity to arsenic include those on protein-poor diets or those with choline (a B-vitamin) deficiency. Inorganic arsenic is detoxified in humans by liver enzymes. Those individuals with low liver enzyme activity or liver damage such as alcoholic- or viral-induced cirrhosis, may be more sensitive to the effects of arsenic than are people with normal liver enzyme activity [16].

Arsenic has been classified by the US EPA and the Department of Health and Human Services as a known human carcinogen. Inhalation exposure to arsenic has been associated with lung cancer. This has been seen in people exposed to arsenic in or around smelters. Ingestion of arsenic has been associated with an increase in the rates of cancers of the skin, liver, bladder, kidney, and lung. The ingestion exposure of on-site workers to the maximum levels of arsenic observed in flue-dust may lead to a high increase in these cancers, especially skin cancer.

Cadmium

Human exposure to cadmium at USS Lead occurred through incidental ingestion of and dermal contact with contaminated surface soils and wastes, and potentially through inhalation of contaminated air. Exposure occurred to on-site workers and trespassers and may have occurred to off-site workers and residents.

The estimated exposure dose for on-site workers through incidental soil ingestion is four times higher than ATSDR's chronic oral MRL, and slightly higher than the US EPA's RfD. Mild damage to the kidney could have occurred to workers at USS Lead because of that exposure. This damage should be very mild because the exposures are very low. Cadmium accumulates in soft tissue such as the kidney. Because it is a cumulative toxin which is highly retained, long-term exposure to low doses produces similar effects as short-term exposure to high doses. Little cadmium is absorbed through the skin, thus dermal exposure is not of great concern.

Impairment of lung function is associated with chronic inhalation exposure to low cadmium levels [17]. Bronchiolitis and alveolitis may occur and impaired respiratory function and emphysema have been observed in persons occupationally exposed to cadmium. Since there is no ambient air data for cadmium, the level of exposure and consequent health effects cannot be determined.

It is not known if cadmium exposure causes cancer in humans. Some epidemiological studies of workers exposed to cadmium suggest a possible link between cadmium inhalation and lung and prostatic cancer [17]. Animal study evidence shows that chronic inhalation of cadmium chloride produces an increased frequency of lung cancer in animals. There is not any human or animal evidence demonstrating that oral or dermal exposure to cadmium causes cancer. Based on animals studies, the EPA has classified cadmium as a probable human carcinogen when inhaled. Workers are unlikely to get cancer from ingesting cadmium. Because sufficient air data is not available, no determination can be made about whether that exposure would have been at high enough levels to cause lung cancer in workers.

Several populations may be sensitive to cadmium exposure. Those with dietary deficiencies in calcium and protein, renal disease, and those who smoke are at an increased risk to the adverse effects of cadmium. The limited amount of cadmium exposure to workers at this site might add to any existing sensitivity to cadmium.

Chromium

Human exposure to chromium at USS Lead occurred through incidental ingestion of and dermal contact with contaminated surface soils and wastes, and potentially through inhalation of contaminated air. Exposure occurred to on-site workers and trespasser and may have occurred to off-site workers and residents.

Chromium is present in the environment in several different forms. The most common forms are chromium 0, chromium III, and chromium VI. Chromium III occurs naturally in the environment, whereas Chromium VI and chromium 0 are generally produced by industrial processes. A maximum of 47% of the total chromium in ferrochrome smelter dust may be bioavailable (capable of being absorbed by an exposed human or animal). Of this amount, about 40% may exist as chromium VI, and the remainder as chromium III [. Based on these assumptions, the estimated dose for the on-site workers through incidental soil ingestion is far below the US EPA's RfD for both chromium III and chromium VI. Therefore, non-cancerous adverse health effects should not occur to on-site workers and trespassers through soil ingestion.

Long-term exposure to high levels of chromium in the air has been associated with lung cancer in people. It is not clear which form of chromium is capable of causing lung cancer, although chromium VI is believed to be primarily responsible. There is no evidence that chromium in any form may cause cancer when exposure occurs through ingestion. The US EPA and the Department of Health and Human Services have determined that chromium VI is a known human carcinogen. No data exists for chromium levels in air, therefore, no determination can be made about whether workers might get cancer from inhalation exposure while working at USS Lead.

Lead

On-site workers and trespassers and off-site workers and residents were exposed to lead through incidental soil ingestion, dermal contact with contaminated soils and wastes, and inhalation of airborne lead-contaminated dust. There are no MRLs or RfDs for lead.

The estimated exposure for on-site workers and off-site pica children far exceeds levels in animal and human studies that caused impaired learning and behavioral tasks in monkeys. The estimated exposure is also high enough to cause mild changes in enzyme activity in the blood, heme synthesis in the blood, and alter motor activity [19]. The highest estimated exposure in workers at the E.C. DuPont plant and in off-site children is similar to these exposure levels.

Additional exposure to lead occurred to both children and adults through the inhalation of air contaminated with lead dust. The amount of lead which would be absorbed through inhalation is not known. The limited air monitoring data available on-site did not exceed occupational standards. However, continuous monitoring conducted off-site at E.C. DuPont exceeded the Occupational Safety and Health Administration's Permissible Exposure Limit for workers of 50 µg/m³ one day in 1985 [13].

Very little data exists concerning adverse effects associated with inhalation exposures of lead. However, maximum concentrations on-site and at E.C. DuPont (38.2 and 16.1 µg/m³, respectively) exceed the concentration of 11 µg/m³ at which some minor hematological changes were observed in people after long exposures.

Children are more sensitive to the adverse health effects from lead exposure than are adults. The central nervous system is the primary target organ for lead toxicity in children [20-24]. Recent studies have indicated the adverse effects on the function of the central nervous system will persist into adulthood [25]. Current information has shown that disturbances in neurobehavioral development occur in children with lead levels in the range of 10 to 25 µg/dl and in children whose mothers had blood lead levels in that range during pregnancy. There has been some indication that effects occur at blood lead levels even below 10 µg/dl [25]. The Centers for Disease Control and Prevention has recommended that the intervention level be established at 10 µg/dl [27]. Suggested actions are the education of parents on simple modifications in food storage and housekeeping activities that will reduce the potential for exposure to lead. In addition, the child's blood lead level should be retested in 3 months if it was between 10 and 14 µg/dl [27].

High levels of lead exposure can cause reproductive effects. The incidence of miscarriages and stillbirths is increased in women exposed to high levels of lead during pregnancy. An increased frequency of spontaneous abortion has been reported in women living near a lead smelter [19]. Studies of male lead workers indicates that male fertility is adversely affected by lead exposure. It is not known whether exposure levels at the site are high enough to cause these effects.

Studies of humans exposed to lead have not established what concentrations of lead present in soil may result in blood lead concentrations associated with adverse noncarcinogenic health effects. Therefore, soil guidelines for protection of public health have not been determined for lead.

The potential for exposure to lead from dermal contact is considered insignificant because little lead passes through the skin [19]. Therefore, adverse health effects from dermal contact with lead contaminated soils and wastes is not expected to be of public health concern.

Case reports have implicated lead as a potential kidney carcinogen in humans [19]. The EPA has concluded that human data are inadequate to determine the potential carcinogenicity of lead exposure. However, based on animal studies,the EPA has classified lead as a probable human carcinogen [19]. Health guidelines for possible cancerous effects in humans resulting from lead exposure have not been established. Therefore, the cancer risk associated with lead exposure at USS Lead cannot be evaluated.

Multiple Exposures

Individuals have been exposed to multiple contaminants at USS Lead by ingestion, inhalation, and dermal contact with contaminated soil and dust. However, data are very limited on the health effects of multiple contaminant exposure. The effects of multiple contaminant exposure can be additive, synergistic (greater than the sum of the single contaminant exposures), or antagonistic (less than the sum of the single contaminant exposures). Also, simultaneous exposure to contaminants that are known or probable human carcinogens could increase the risk of developing cancer. ATSDR's evaluation of exposures in this preliminary public health assessment is limited to individual contaminant exposures; multiple exposures have not been evaluated because of the limited knowledge that exists about the toxicity from multiple exposures. The only available information regarding interactions between two or more of the metals at this site is for cadmium and lead. Cadmium may act synergistically with lead, when a person is exposed to both metals simultaneously. Increased mortality rates and behavioral changes have been reported in animal studies using both metals [19]. No information is available regarding other possible interactions, or the lack of interactions between the metals at this site.

B. Health Outcome Data Evaluation

The Indiana State Board of Health conducted blood lead screening for children in East Chicago [3]. The study included children aged six months to six years, and was performed over a two day period in June, 1985. USS Lead was still in operation at the time of the study. It is not clear what criteria were used in selecting the children for this study. Fifty-three children were tested by finger-stick for elevated blood lead levels. Two children were found to have class II blood lead levels, indicating that they were moderately increased, between 10 to 20 µg/dl. The home environments of both children were investigated by the East Chicago Health Department. No conclusive results were found regarding the sources of the lead contamination. One home was built in 1977, with no lead found in paint or soil. The other residence was an apartment undergoing remodeling. No conclusions regarding the impact of the site on children in the area can be drawn from the limited information currently available about this study.

C. Community Health Concerns Evaluation

No community concerns have been identified.

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