PUBLIC HEALTH ASSESSMENT
NATIONAL LEAD INDUSTRIES/TARACORP LEAD SMELT SITE
GRANITE CITY, MADISON COUNTY,ILLINOIS
To determine if nearby residents are exposed to site-related contaminants migrating off the site, IDPH evaluates exposure pathway components. An exposure pathway consists of five elements: 1) a source of contamination, 2) transport through an environmental medium, 3) a point of exposure, 4) a route of human exposure, and 5) an exposed population. If any of these elements are missing, the exposure pathway is not complete.
Completed pathways require that the five exposure elements exist and that exposure has occurred in the past, is currently occurring, or will occur in the future. Potential pathways have at least one element missing, but the missing element(s) could exist. Potential pathways suggest that exposure could have occurred in the past, could currently be occurring, or could occur in the future. An exposure pathway is eliminated if one or more of the elements are missing and will never be present. Table 26 identifies the completed exposure pathways, and Table 27 identifies the potential pathways.
Surface Soil Pathways
Past, current, and future exposure to contaminated on-site and off-site soils is assumed to be occurring at several exposure points including residential yards, playgrounds, and on-site soil. Bare areas at these exposure points may greatly increase exposure because it allows direct contact to and disturbance of the soil.
Contamination of the surface soils may have occurred by several mechanisms including airborne deposition from the waste piles, contaminated soils, site operations, and SLLR activities; surface runoff; and tracking and fugitive dust generation from vehicles. Air deposition of site contaminants is illustrated by the lead soil concentration map (Figure 8), which shows that lead concentrations decrease with increased distance from Taracorp.
Past exposure of workers to on-site surface soils has surely occurred. Using protective clothing and proper hygiene should greatly reduce or eliminate current and future exposures to contaminants in on-site soils by employees or site remediation workers. Exposure may occur by ingestion and inhalation.
Exposure in residential yards has surely occurred in the past and continues to occur. Those most susceptible to exposure to contaminated residential soil are small children who play in the soil, especially those children closest to the site playing in soil with almost no groundcover. Ingestion would be the primary route of exposure, especially with younger children. Inhalation may also be a route of exposure, especially when surface soils are dry.
The site-related contaminants that residents would most likely contact in the soil would be the same ones that have high concentrations in the waste piles and those that were in the smelter stack emissions. These contaminants would include antimony, arsenic, cadmium, chromium, lead, nickel, and zinc. Of these contaminants, lead has the highest concentration in the waste and off-site soils. The number of persons that would be most highly exposed to off-site soil contaminants would be the approximately 8,000 persons within a 1/2-mile radius of the site.
Since the shutdown of Taracorp smelting operations in 1983, the primary routes of lead exposure to area residents have been through the ingestion and inhalation of contaminated soils and dust. In addition to the possible contribution of maternally-derived lead from long-term female residents of the area, another important source of site-related lead exposure to the most sensitive segment of the population (preschool children) has been directly or indirectly through soil and dust contamination. This exposure consists primarily of:
- direct ingestion of contaminated soil by children,
- transfer of contaminated dusts to mouth by hands,
- swallowing of inhaled airborne particulates too large to penetrate to the lung,
- ingestion of food or liquids contaminated by lead-containing soils or dusts, and
- inhalation of lead-contaminated particulates small enough to penetrate to the lung.
Additional exposure to lead may be occurring through old exterior and interior paints, plumbing, dietary sources (particularly canned foods), tobacco smoke, and parental occupations or hobbies. Given the air emissions originating from the smelter and the long half-life of lead in the body, long-term residents of the area may have received a significant lead exposure.
Past, current, and future exposures have occurred and will continue to occur from the Taracorp waste piles, site operations, and contaminated soils both on and off the site. Past exposures, and to a lesser extent current and future exposures, will occur from plant process operations on the site. Past exposures may also have been higher than the present, since the piles were disturbed, especially with excavation by SLLR. Future remediation of the site also may increase airborne exposure.
Ambient air monitoring, especially for lead, has been conducted in the Granite City area since 1977. The air data seem to show a decline in some inorganic chemicals including lead. The reduction in lead in ambient air coincides with the cessation of secondary smelting at Taracorp and closure of SLLR. Other factors may have contributed to this decline including phasing out leaded gasoline and the decline of industry in Granite City. Areas with the highest inorganic ambient air contaminants are at 15th and Madison and 2001 E. 20th Street. Another source of lead near Taracorp and these air monitors is Granite City Steel. The yearly arithmetic mean for ambient air lead levels have not exceeded the NAAQS level of 1.5 µg/m3 since 1981 at the 15th and Madison location. At the same location, the NAAQS was last exceeded in the first quarter of 1984. The NAAQS may be reduced in the future based on additional data review.
Many residential yards and a gravel parking lot next to the site boundary owned by Tri-Cities Trucking may allow contaminated soil and dust to become airborne, especially on windy days. The waste piles and soil on the Taracorp property are currently uncovered and winds may move contaminated soils and dust to residential areas.
The population affected by the site would include workers on the site and residents in areas surrounding the site. Exposure of on-site workers and adjacent populations to lead would likely occur by both inhalation and ingestion. Inhalation of lead on the site would occur by breathing suspended dirt and waste pile particles and possibly by breathing fumes and dusts from on-site processes. Ingestion of lead by workers would likely be accidental; however, inadvertent ingestion may occur indirectly from inhalation. Inhalation would occur off the site by breathing contaminated dust and soil from the waste pile and on- and off-site soil. Release from the waste pile is reduced by treatment with a dust suppressant twice per year. Ingestion of contaminated soil would occur accidentally by adults and children, but ingestion of contaminated soil by children may be a significant route of exposure.
Vegetable and Fruit Pathways
Past, present, and future exposures may occur in residents who garden or eat fruits and vegetables grown near Taracorp. Past exposures to inorganic chemicals on fruits and vegetables would come from contaminated soil and airborne deposition. The airborne concentrations of some contaminants, especially lead, were much higher near the site before 1983. Deposition of lead on vegetables may contribute more to their inorganic content than from uptake from the soil. In 1982, vegetable samples were taken in the neighborhoods near Taracorp. The results of these samples showed that the lead in vegetables correlated with soil lead levels. These areas of higher soil lead are closer to the site and deposition also may add to the lead concentration in these vegetables. Airborne deposition of inorganic contaminants on local fruits and vegetables probably continues, but to a lesser degree than in the past.
The contribution of vegetables to exposure to inorganic compounds will depend on several factors including the percentage of the diet made up of homegrown vegetables and vegetable preparation (e.g., washing). Lead was the only inorganic compound chosen for analysis in vegetables, but plants also take up both arsenic and cadmium. The rate of uptake is dependent on a variety of factors including pH, phosphorus, and other metals present in the soil. Inorganic arsenic taken up by plants may be converted to an organic form that is less toxic than the inorganic form. The number of gardeners near Taracorp is not known.
Exposure to the waste pile has occurred from activities associated with the pile including adding, moving, and removing materials. Taracorp and SLLR employee exposures to waste pile contaminants are certain to have occurred in the past. Disturbing the waste piles in any way is currently prohibited. The waste pile is scheduled to be capped in the future.
Past, present, and future exposures to site-related contaminants in groundwater are possible. Migration of chemicals off the site may be occurring; however, the extent of the contamination is not fully known. In the past, residents may have had private wells, but off-site groundwater contamination in the past may not have existed. Currently no residential drinking water wells were identified within 0.25 miles downgradient of the site. All residents in Granite City, Madison, and Venice use municipal water and exposure to groundwater is unlikely. Future exposures are unlikely to occur since municipal water is available to all area residents.
Surface water runoff from the site enters the storm sewers, and is treated at the municipal water treatment plant before being released to the Mississippi River. No surface water bodies are contaminated by the site, since all surface runoff water enters the storm sewers. In the area between the site boundary and the storm sewers, children could be exposed to contaminants by ingestion and dermal contact if allowed to play in the contaminated storm water runoff. Since such exposures would likely be infrequent and at low levels, this pathway is not expected to pose a health hazard.
Exposure to waste pile contaminants could occur in the future if the waste pile is disturbed during remediation. This could potentially represent a very significant exposure to both workers and residents near the site. The waste piles have very high concentrations of inorganic contaminants, especially antimony, arsenic, cadmium, lead, and zinc. The number of residents that would be exposed would be at least those within 0.5 miles of the site (approximately 8,000 persons) and an unknown number of on-site workers.
To evaluate health effects, ATSDR has developed Minimal Risk Levels (MRLs) for chemicals commonly found at hazardous waste sites. An MRL estimates the daily human exposure to a contaminant below which adverse, non-cancer health effects are not likely to occur. MRLs are developed for different routes of exposure, and for three different exposure periods: acute (less than 14 days), intermediate (15-365 days), and chronic (more than 365 days). At Taracorp, the only site contaminant that has an MRL is cadmium. When an MRL is not available for a contaminant of concern, a USEPA reference dose (RfD) was used, if available. RfDs are used for long-term exposure, and may not be protective of hypersensitive individuals. ATSDR has developed Toxicological Profiles for contaminants that are common at hazardous waste sites. The profiles contain information on health effects, environmental transport, human exposure, and regulatory status of each chemical.
IDPH considers three types of individuals when evaluating exposure: adults, children, and pica children. Adults have larger body weights, breathe more air, and ingest less soil than children. Pica children have excessive hand-to-mouth activity and are prone to ingest more soil than a typical child. Exposure to soil is reduced somewhat by the fact that the ground is frozen during winter months. All site-related chemicals in soil may be inhaled or ingested.
Most of the health effects associated with lead are the result of chronic, low level exposures. Acute effects of lead intoxication are similar to chronic effects, but occur rarely. Acute effects can be severe and include encephalopathy, which may result in death. Chronic effects of lead intoxication vary depending on exposure levels. Some health effects attributed to lead exposure are interference with Vitamin D production, neurobehavioral toxicity, renal dysfunction, and, at higher exposures, dysfunction of cardiovascular, hepatic, gastrointestinal, and endocrine systems. USEPA presently classifies lead as a B2 carcinogen for both inhalation and ingestion. There is evidence that it is a carcinogen in animals at high doses; however, there is insufficient evidence that lead causes cancer in humans. Animal data suggest that lead is not a very potent carcinogen.
The greatest concern for lead is based on its effects on the nervous system, particularly in young children. Lead's effects on nervous system development was recognized early in this century, but was assumed to be reversible until the 1940s, when researchers reported permanent effects on learning and behavior in children exposed to lead. A continual reduction in the acceptable body burden has accompanied the expanding knowledge of the adverse effects of lead. The acceptable level of lead in children's blood has dropped from 60 g/dL in the 1950s to the current Centers for Disease Control and Prevention (CDC) level of 10 g/dL. This does not imply that a safe level of blood lead has been identified. In the last few years, several studies have been conducted and are still ongoing that suggest children may suffer neurological and developmental deficits at blood lead levels well below the current standard. While not universally accepted, these studies seem to suggest that prenatal and postnatal exposures at levels of 10-15 g/dL are associated with low birth weight, reduced growth rate, cognitive deficits, and a reduction in neurologic development as measured by IQ. Blood lead levels were demonstrated in the past to be elevated for both workers and some area residents, including children 5 years of age and under. No human studies have provided information on what a safe dose of lead would be, but a 10 kg child who ingested the maximum off-site soil lead level, 9,493 mg/kg, would have an estimated exposure dose that would exceed the lowest observed adverse effect level (LOAEL) seen in monkeys (0.05). Eighty nine children from 6 months to over 15 years of age had blood lead levels in the past that were over 10 g/dL. Of that number 16% were in the 6 - 71 month age range, which is considered the most vulnerable age group for adverse effects.
Children are prone to lead exposures higher than adults and are much more sensitive to the neurological effects. The differences that increase a child's sensitivity to lead include an increase in lead intake into the respiratory and gastrointestinal tract on a body weight basis; greater absorption and retention rates; differences in behavior, including hand to mouth activity; and greater prevalence of deficiency of nutrients that affect absorption in the gastrointestinal tract.
Studies also show that the fetus is at risk from environmental lead exposure as well. Pregnancy and lactation may mobilize the lead from maternal bone stores in a manner identical to calcium mobilization. Lead will cross the placenta and the fetus may serve as a place for the mobilized maternal lead to accumulate. In women of childbearing age, pregnancy and lactation may serve to mobilize bone lead to the detriment of the fetus and infant.
While much attention has focused on the hazard of lead to the fetus and child, additional studies are suggesting chronic health risk to adults as well. Some studies have shown that elevated blood lead levels in middle-aged males may increase their risk of developing hypertension. It has also been suggested that lead may aggravate osteoporosis in postmenopausal women when bone lead stores are released by the demineralization processes. There is a considerable body of animal and epidemiological evidence pointing to serious chronic health problems posed by lead exposure; however, the relative importance of different environmental lead sources is unclear. Some former employees that participated in biomonitoring in 1986 and 1987 had elevated blood lead levels. The highest level found was 56 g/dL. A 70 kg worker who ingested the maximum on-site lead level would have received a dose above the LOAEL for monkeys. As previously stated, human LOAEL data are not available.
The hazards posed by lead in the home, workplace, and environment are undisputed. Current research suggests that lead may have deleterious effects at lower levels than previously thought and that many children may be at risk from lead. There is a question, in fact, about whether there is a threshold for the adverse effects of lead. The degree to which lead in soil poses a hazard and the magnitude of that hazard is not as clear, and may depend on socioeconomic and behavioral factors such as level of education, household income, and personal hygiene. The concern over soil lead concentrations arises over the observation that direct soil contact may result in inadvertent soil ingestion by children that may, in turn, significantly increase lead exposure. Some studies have linked children's blood lead to the lead levels in exterior and interior soils and dusts. The significance of this relationship appears to vary widely, but a positive relationship is always seen. Potential confounders were obviously not completely considered in many of these studies, but they often illustrate the interdependence between environmental sources and socioeconomic factors.
The population exposed to arsenic would be the same as those exposed to lead. Exposure may occur by ingestion or inhalation. Adverse health effects associated with arsenic are most notably that it is a known human carcinogen by inhalation and ingestion. Using standard exposure assumptions, the RfD is exceeded for the pica child, child, and adult exposures to arsenic in soil.
The highest concentration of arsenic in surface soils was taken along Taracorp's northeastern boundary. If persons were exposed to this soil, only 2 of 77 the surface soil samples might lead to exposure that exceeds the oral RfD for adults. Thirty-one of 72 surface soil samples might lead to exposure that exceeds the RfD for exposed children. All 77 surface soil samples had arsenic levels that might lead to exposure greater than the RfD for exposed pica children (Table 28). If this soil is ingested at these levels, symptoms may occur.
Noncarcinogenic effects that may be associated with inorganic arsenic include irritation of the stomach and intestines with symptoms including nausea, vomiting, and diarrhea; a decrease in the production of red and white blood cells, abnormal heart function, blood vessel damage, and impaired nerve function causing a "pins and needles" sensation in the hands and feet.
Long-term ingestion of arsenic may also lead to a pattern of skin changes including a darkening of the skin and the appearance of small "corns" or "warts" on the palms, soles, and torso. These skin changes are not necessarily a health concern by themselves, but they may later develop into skin cancer. Chronic ingestion of arsenic has also been reported to increase the risk of liver, bladder, kidney, and lung cancers.
There is evidence that inhalation of inorganic arsenic causes lung cancer in humans. The range of yearly arithmetic mean concentrations in ambient air for the 13 years that arsenic has been monitored in the Granite City area is 0.002-0.039 /m3. A low increased risk of lung cancer from arsenic exposure existed at that time for persons who breathed this air in Granite City.
Antimony was found in off-site soil at levels from 2 ppm to 80 ppm. Five of 39 off-site soil samples had antimony levels that might lead to exposure that would exceed the oral RfD for exposed children. All thirty-nine samples had antimony levels that might lead to exposure that would exceed the oral RfD for an exposed pica child. Antimony was not analyzed in either on-site or off-site air. Exposure to antimony on the site and near Taracorp may cause adverse health effects including irritation to the eyes, skin, and lungs; and sometimes heart problems, vomiting, and diarrhea.
Seventy-seven surface soil samples taken near Taracorp were analyzed for cadmium. All cadmium levels might lead to exposure that exceeds the chronic oral MRL for an exposed pica child, while 5 of 77 samples contained cadmium at levels that might lead to exposure greater than the chronic MRL for exposed children. Cadmium would not be a health hazard to exposed adults. Health effects that may be associated with oral cadmium exposure are a build-up of cadmium in the kidney that may cause kidney damage, and fragile bones. This build-up of cadmium in the kidneys is also observed in inhalation exposures. While ambient airborne concentrations of cadmium did not exceed the MRL for cadmium in air, it affects the body in the same way as ingested cadmium and provides an additional exposure.
The yearly range of arithmetic means for ambient air concentrations between 1977 and 1990 was 0.003 - 0.011 g/m3. The data on cadmium inhalation and cancer in humans are limited. Based on the available information, no apparent increased cancer risk would be expected in Granite City due to exposure to airborne cadmium.
Chromium exists in several forms in the environment including chromium III and chromium VI. Chromium III is the naturally occurring form and is an essential nutrient. Chromium VI is usually associated with industrial activities. Chromium analyses in both air and soil samples did not differentiate between chromium III and chromium VI. Even if all the chromium in the soil is chromium VI, the exposure to chromium in the soil is not a health hazard for adults and children. Exposure to chromium in the soil by a pica child may exceed the RfD in 75 of 77 samples (Table 28). The health effects associated with chromium in off-site soils would not be expected to cause any problems in the general population; however, allergic individuals may have redness and swelling of skin if they come into contact with soils with high chromium levels.
The airborne concentrations of chromium in ambient air based on yearly arithmetic means between 1985 and 1990 were 0.002-0.032 g/m3. Intermediate and chronic health effects associated with breathing chromium could appear in the population near 2001 E. 20th Street. This assumes that all the chromium is chromium VI, and this is probably not the case. Chromium is not expected to produce adverse health effects in most individuals; however, persons who are allergic to chromium may have asthma attacks.
Long-term exposure to elevated chromium levels in the workplace has been associated with lung cancer. Chromium VI is associated with lung cancer, while chromium III is not. The levels of chromium identified in the ambient air in Granite City are less than for those individuals exposed to chromium in occupational studies.
Thirty-eight soil samples taken near Taracorp were analyzed for nickel. The range of nickel in the soil was 14 to 84 ppm. Exposure to nickel at these levels would not be a health hazard for children and adults. Oral exposure to nickel in soil for a pica child was estimated to equal or exceed the RfD in 8 of 38 samples. The health effects associated with nickel at higher levels are increased red blood cells and protein in urine from damage to the kidneys. In an allergic person, skin contact with nickel can cause a skin rash.
Ambient airborne nickel concentrations in Granite City were 0.001 to 0.021 g/m3. Nickel and certain nickel compounds are lung, nasal, and sinus carcinogens. These cancers have been identified in workers who work with airborne nickel concentrations of 1,000 g/m3 or greater. The levels of nickel found in Granite City air are much lower. No apparent increased cancer risk would be expected due to exposure to nickel in air.
Zinc is an essential nutrient. The health effects associated with zinc are non-carcinogenic and have been reported in individuals ingesting and inhaling zinc at higher levels than those that would be encountered in Granite City. In fact, an estimated dose that a 10 kg child would likely ingest if exposed to the highest level of zinc found in off-site soil is below the no observed adverse health effects for humans. The health effects from breathing high levels of zinc in the workplace include breathing difficulties and a brief sickness called metal fume fever. At very high levels, breathing zinc dust or fumes may be life threatening. Ingestion of too much zinc can cause anemia and digestive problems. Excessive zinc intake may also be associated with an increased risk of heart disease and trouble in fighting disease or infection.
Three studies were conducted by IDPH because of concern over the high lead concentrations measured in air while the lead smelter was in operation. The first study sampled residents of Granite City and Madison in late 1982. The second study sampled residents of Venice in late 1983. The results of the blood lead testing are as follows (measured in micrograms per deciliter):
|N||Blood Lead (µg/dL)|
|N||Blood Lead (µg/dL)|
The mean blood lead levels for children in the U.S. based on the NHANES II study for ages 0.5 to 5.0 years was 16 µg/dL. The results of the blood lead testing in 1982-1983 suggest no unusual elevation in these children.
No attempt was made to correlate blood lead levels to exterior soil lead levels, although some attempt to identify interior lead sources was made in individuals identified as having high blood lead (then defined as 30 µg/dL). The utility of this work in assessing the hazards posed by environmental lead has been called into question due to:
- the small numbers of individuals (especially children) sampled, and
- the time of year (late fall) that the sampling was conducted.
In response to concern generated by the planned remedial action and in recognition of new information about the hazards of lead exposure, IDPH and ATSDR began the third study, a large epidemiological investigation of lead exposure in these communities in 1991. Eight hundred twenty-seven people from the area surrounding the site participated in the Madison County Lead Exposure Study. More than 600 children provided biological samples for lead testing and other biomedical analyses. Of these, 490 children under the age of six participated in the study. Environmental sampling also was conducted at the homes of these children. This sampling included soils, household dust, drinking water, and interior and exterior paint analyses. The results of the biological monitoring were correlated with questionnaire data in an attempt to discern which factors are the most important determinants of lead body burdens. The conclusions of the study were:
- most children under the age of six years had blood lead levels of concern (>10 µg/dL),
- house dust served as a major source of lead exposure in small children living near the site and the source of lead in house dust was the lead in paint and soil,
- soil lead levels had a small, but statistically significant, contribution to the variance on the child's blood lead level, and
- many personal variables influence lead uptake (i.e., behavior, socioeconomic status, education, and smoking) and variables present at a particular house.
Sixty percent of the lead uptake was unaccounted for by variables used in the study.
The youngest age group of children 6 months to 71 months in the Madison County study was 18.7 times more likely to have detectable urine cadmium levels greater than 0.1 µg/g creatinine than were young children in study areas in Pennsylvania, Missouri, and Kansas. This observation could not be explained by different cadmium levels in environmental media. The urine cadmium levels were also not associated with any personal behavior variables in the four-state study. This may show a small but detectable cadmium exposure in young children in the area surrounding Taracorp.
Lung cancer incidence for Granite City, Madison, and Venice were compared with those of Madison County, Illinois. The age adjusted lung cancer rates for the zip codes for Granite City (62040), Madison (62060), and Venice (62090) were based on a five-year average from 1990 to 1994. The rates are number of deaths from lung cancers per 100,000 persons in the population. The data are broken down by sex but not by race due to the small sample size in the zip codes. The age-adjusted cancer rates were used with population data from the 1990 census. Both the county and zip code data were adjusted to the 1970 cancer rates so that they could be compared. This standardized rate ratio method to calculate the observed rate (zip code) and the expected rate (county) is a useful indicator of the relative exceedances of cases in the study group. This comparison is not a statistical test. Generally, 0.8 to 1.2 is similar or approximate the rate in the reference group. If a zip code has fewer than 10 cases of a particular cancer, the rates are not considered stable or reliable.
The rates ratio for Granite City, Madison, and Venice for both men and women are:
The sample numbers for men and women in Venice were N=0 and N=4, respectively, both of which were too small to assess the lung cancer rates ratio. The rate ratio for males in Granite City was the only one that was within the expected rate. The rate ratio for lung cancer in both males and females in Madison and females in Granite City are slightly above the expected range; however, this does not necessarily indicate an elevation in lung cancers. A cluster investigation in Granite City and Madison may eliminate bias and would explain the slight increase in the ratio over the expected rates.
Skin cancer rate ratios could not be determined from the data received by the IDPH Division of Epidemiological Studies. Their data base does contain melanoma information for the state and counties, but it is not currently available for zip codes. In addition, only melanomas were recorded and not other skin cancers. The skin cancer types most frequently associated with arsenic exposure are squamous cell carcinomas and basal cell carcinomas.
The community health concerns have been addressed as follows:
1. What are the effects of lead on health?
Acute effects of lead intoxication are similar to chronic effects, but occur rarely. Acute effects can be severe and include encephalopathy that may result in death. Most of the health effects associated with lead are the result of chronic low level exposures. Chronic effects of lead intoxication vary depending on exposure levels. Many health effects of chronic low level exposure are very generalized and not easily seen as caused by lead exposure. Some health effects are not observable at all.
Some health effects attributed to lead are interference with Vitamin D production, neurobehavioral toxicity, and renal dysfunction. At higher exposures, effects include dysfunctions of cardiovascular, hepatic, gastrointestinal, and endocrine systems. USEPA presently classifies lead as a possible human carcinogen for both inhalation and ingestion.
2. Why are children more sensitive to lead's effects?
Children are prone to incur lead exposures that are higher than adults and they are much more sensitive to the neurological effects. The developing nervous system of a child is much more susceptible to the effects of lead. Children also display adverse health effects at much lower lead exposure than adults.
The differences that increase a child's exposure versus an adult's exposure to lead include:
- An increase in lead intake into the lungs and digestive system on a body weight basis.
- Greater absorption of lead into the body by the digestive system and more difficulty eliminating lead from the body.
- Increased mobility of lead in a child's body.
- A more frequent occurrence of nutrient deficiencies that lead to increased absorption from the digestive system into the body.
- Differences in behavior that increase lead exposure including -
- Crawling and playing on the floor or ground
- Placing non-food items into the mouth
- More hand to mouth activities
- Lack of hand washing before eating
3. Where does lead come from and how does exposure to lead occur?
Lead is a naturally-occurring metal in the earth's crust. It is used in a variety of products including automobile batteries, ammunition, and some paints. Its use has been reduced or eliminated in many products including solder, paint, and gasoline. Lead in the Granite City area also may come from several industries. The industry that has probably contributed the most lead to the area is Taracorp. Taracorp was the site of a secondary smelter, where lead slag and automobile batteries were smelted to reclaim the lead. Smelting was ceased at this location in 1983. Taracorp still has approximately 250,000 tons of lead-containing waste in several piles on the site.
Lead exposure from the Taracorp site may occur by inhaling lead from on-site operations, wind blown dust, or lead contaminated soils either on or off the site. Additionally, exposure to lead may occur by ingesting contaminated off-site soils or vegetables. Ingestion of soil lead will probably be highest in children under the age of six years, since they have the greatest amount of hand to mouth activity.
4. Is lead exposure related to cancer?
USEPA presently classifies lead as a possible carcinogen for both inhalation and ingestion. There is evidence that it can cause cancer in animals at high doses; however, there is insufficient evidence of its ability to cause cancer in humans. Animal data suggest that lead is not a very potent carcinogen. The U.S. Department of Health and Human Services has determined that lead acetate and lead phosphate may reasonably be anticipated to be carcinogens. Lead acetate and lead phosphate are lead-containing compounds that are not associated with the Taracorp site.
5. Are garden vegetables safe to eat?
If the soil is removed from root vegetables and all vegetables are washed to remove air-deposited lead, the vegetables should be safe to eat from a lead standpoint. The exposure to other contaminants, particularly cadmium, is not known since vegetables were not analyzed for cadmium concentration. Cadmium is taken up by plants and the extent of this uptake in the garden plants grown near Taracorp is not known.
6. Will blood tests for lead be made available?
Blood tests were made available by IDPH for residents of Granite City, Madison, and Venice as part of the blood lead study. This testing began in August 1991. There are currently no IDPH-sponsored testing of individuals in the Granite City, Madison, and Venice area.
7. What is the basis for the 500 parts per million cleanup level?
The 500 parts per million residential soil cleanup level for lead was set by USEPA. USEPA supported this cleanup level in the amended ROD based the USEPA's Integrated Exposure, Uptake, and Biokinetic Model for Lead.