EAST ST. LOUIS, ST. CLAIR COUNTY, ILLINOIS
Comparison values are used to screen contaminants for further evaluation. Comparison values are contaminant concentrations in specific environmental media used to select contaminants for further evaluation. These values include Environmental Media Evaluation Guides (EMEGs) for chronic exposures (CEMEGs), intermediate exposures (IEMEGs), Cancer Risk Evaluation Guides (CREGs), and other relevant guidelines. CREGs are estimated contaminant concentrations based on a one excess cancer in a million persons exposed over a lifetime. CREGs are calculated from USEPA's cancer slope factors.
A list of the contaminants that exceeded comparison values in the soil samples collected by IEPA on April 5 and 6, 1994, are summarized in Table 2. The listing of a contaminant does not necessarily mean that it will cause adverse health effects if exposure occurs. The primary contaminants of concern are PAHs in soil. The soil samples that contained PAHs at levels greater than comparison values or levels greater than background samples are X102, X105, X106, X107, X110, and X111. Samples X102, X105, X106, and X107 are on-site samples, and samples X110 and X111 are from residential soil. The inorganic compounds detected in the samples at levels above comparison values are arsenic, beryllium, lead, mercury, and thallium. None of the metals appear to be site-related.
The arsenic levels identified off the site are not at levels of health concern for children, and those on the site are not at a level of concern for adults. Beryllium levels in soils, including the background sample, exceed the CREG; however exposure would not result in a dose that would warrant a health concern. The lead concentration of 3,320 parts per million (ppm) in a residential soil sample may be of concern. The source of this lead does not appear to be site-related. Mercury and thallium are detected at their highest levels in the on-site soil samples, but no activities on-site would be considered a source of contamination. Inorganic compounds at the levels detected on the site and off the site are not expected to be a public health concern, except for the lead concentration of 3,320 ppm in the residential soil sample X112. Additional sampling may be necessary to determine the extent of the lead contamination.
Pesticides were detected on and off the site. Heptachlor epoxide was identified on the site at a level above the CREG; however, based on the low concentrations and the fact that it was on-site, no one is expected to come into contact with the heptachlor epoxide in a way that would result in a dose expected to cause adverse health effects. Dieldrin was detected at its highest level in a residential yard, which suggests possible residential application. The levels of dieldrin detected are above the CREG in most cases, but all levels are below the chronic EMEG for children and would not be expected to cause noncancer, adverse health effects.
Although Aroclor-1254 was detected in one of the samples on the site, the level was less than the comparison value for adults and children. Aroclor-1260 was detected in six of the eight on-site samples and one of the residential soil samples. Aroclor-1260 is not expected to cause adverse health effects at these levels found.
Table 3 shows soil exposure estimates for on-site workers and children off the site. The table depicts estimates for both cancer and noncancer endpoints. No adverse health effects would be expected for on-site workers or the children exposed to off-site soil. For worker exposure, IDPH staff assumed that the workers would ingest 100 milligrams of soil, 5 days a week for 50 weeks each year for thirty years. For children exposed to off-site soil, IDPH staff assumed that children would ingest 100 milligrams of soil every day for 10 years. When calculating the exposure estimates, IDPH staff used the maximum concentrations detected in the samples.
IDPH staff used the USEPA slope factor to calculate the estimated carcinogenic risk that may occur from ingestion of arsenic at the site. A low increased cancer risk was estimated for children exposed to arsenic in off-site soils. Noncarcinogenic health effects would not be expected from ingestion of concentrations detected in soil both on and off the site.
The population that is currently exposed to PAHs are the workers at the three businesses and nearby residents (Table 4). The exposure routes include inhalation, ingestion, and dermal absorption. Inhalation and ingestion are probably the most significant routes of exposure. The primary health concern when considering exposure to PAHs is their carcinogenic potential. Benz(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, and indeno(1,2,3-c,d)pyrene are classified as known animal carcinogens by the U.S. Department of Health and Human Services. The International Agency for Research on Cancer has listed the human carcinogenic potential for the following PAHs as follows:
- benz(a)anthracene, and benzo(a)pyrene are probable human carcinogens;
- benzo(b)fluoranthene, benzo(k)fluoranthene and indeno(1,2,3-cd)pyrene are possible human carcinogens;
- benzo(g,h,i)perylene, chrysene, phenanthrene are not classifiable as human carcinogens due to a lack of adequate data.
A probable human carcinogen is one that can reasonably be anticipated to be a human carcinogen based upon sufficient animal data but limited human data. A possible human carcinogen is one that can also be reasonably anticipated to be a human carcinogen based upon sufficient animal data but without human data.
Benzo(a)pyrene (BaP) is the only PAH that has a Cancer Risk Evaluation Guideline (CREG). BaP levels exceeded the 0.1 ppm comparison value in all samples, including the background samples, except sample X102. The background level for benzo(a)pyrene ranged from 0.165 to 0.22 ppm. The carcinogenic risk for PAHs was calculated by using the relative potency of each carcinogenic PAH to BaP. Table 3 presents calculated cancer risks for both children and adults who may be exposed to PAHs on and near the site. Neither children nor adults have an increased risk of developing cancer as a result PAH exposure. Likewise, no one is expected to experience noncarcinogenic, adverse health effects as a result of exposure to the PAHs found on and near the site.