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PUBLIC HEALTH ASSESSMENT

BOHN HEAT TRANSFER FACILITY
BEARDSTOWN, CASS COUNTY, ILLINOIS


DISCUSSION

IDPH compared the concentration of each contaminant detected during environmental sampling with the appropriate comparison values developed by the Agency for Toxic Substances and Disease Registry (ATSDR). The comparison values are used to select contaminants for further evaluation for exposure and for further evaluation for any resulting carcinogenic and non-carcinogenic health effects (Attachment 1). Chemicals found at levels greater than comparison values or those for which no comparison values exist were selected for further evaluation. At the Bohn site, chemicals exceeded comparison values in on-site and off-site groundwater and in two on-site soil samples.

Pathway Analyses

IDPH evaluates the environmental and human components that lead to exposure to determine whether nearby residents are exposed to contaminants migrating from a site. A hazardous chemical can affect people if they are exposed to high enough levels for a sufficient period. A source of contamination, transport of the contaminant in the media of concern, a point of contact, a route of exposure, and an exposed population must all be present for an exposure to occur. Exposure pathways are either completed or potential. All five elements are present in completed exposure pathways, but at least one element, although possible, has not been identified in potential exposure pathways. Although no completed exposure pathway presently exists at the Bohn Heat Transfer Facility, future potential groundwater and soil exposure pathways have been identified (Table 11).

The main concern at the site is exposure to contaminated groundwater. The contaminants of interest in groundwater are organic solvents, including 1,1,1-TCA and TCE. If groundwater contamination migrates far enough, individuals using the Beardstown public water supply could be exposed to those contaminants. Off-site groundwater is contaminated, but no completed exposure pathway presently exists. No site-related contaminants were detected in the nearby private well and the public supply wells. Currently, no one uses groundwater immediately downgradient from the loading dock area of the site, so no exposure to on-site groundwater takes place.

Contact with contaminated soil is not a current hazard at the site. Remedial actions taken in 1982 included removal of contaminated soil from the loading dock area and replacement with clean sand and gravel. Subsequent soil sampling in 1989 and 1990 revealed the presence of VOCs, but those chemicals were present only in subsurface soil. Two on-site surface soil samples collected in 1989 contained PAHs; however, a 6-foot-high, chain-link fence surrounds the site, so access is limited. IDPH did not evaluate exposure to PAHs because the site is secure, and no one is exposed to on-site soil. Future construction activities could expose workers and nearby residents to contaminated surface and subsurface soil by generating contaminated dust and by bringing contaminated soil to the surface.

Public Health Implications

Trichloroethylene

The highest level of TCE detected following the 1983 groundwater investigation was 3,200 ppb. That sample was collected on March 25, 1993, from Hydro-punch 18, next to the intersection of Route 125 and Beardstown Road (Table 7 and Figure 6). The maximum contaminant level (MCL) for TCE is 5 parts per billion (ppb) and ATSDR's comparison value is 3 ppb (11). The MCL is the maximum level of a contaminant allowed in public drinking water supplies.

IDPH estimated the dose of TCE for children and adults through ingesting groundwater containing the maximum TCE level and found that exposure to that level of TCE could pose a moderate increased cancer risk (12).

The estimated exposure to children and adults is less than the no-observed-adverse-effect levels (NOAELs) for TCE in animals. NOAELs reflect actual doses used in animal studies that did not result in observable health effects. Studies of humans exposed to TCE in drinking water suggest that adverse health effects may include skin rashes, liver problems, urinary disorders, anemia and other blood disorders, and diabetes, but levels that might cause those effects are not well established, and no one at the site is currently being exposed to any TCE from the site (13). The health information for whether TCE may cause cancer and birth defects is controversial; study findings are mixed partly due to differing study methodologies. The carcinogenicity of TCE is under review (13).

1,1,1-Trichloroethane

The highest level of 1,1,1-TCA detected following the 1983 groundwater investigation was 620 ppb. That sample was collected in December 1994 from monitoring well 901S immediately downgradient from the loading dock area (Table 8). The MCL for 1,1,1-TCA is 200 ppb (11).

IDPH estimated the dose for children and adults to this chemical through ingestion of groundwater, but no ATSDR health guideline exists for 1,1,1-TCA. The estimated exposure to children and adults is less than the NOAELs for 1,1,1-TCA in animals and would not be expected to result in adverse health effects in humans (14). The human carcinogenicity of 1,1,1-TCA has not been classified.

Cis-1,2-Dichloroethene

The highest level of cis-1,2-DCE detected following the 1983 groundwater investigation was 1,200 ppb. This sample was collected on March 25, 1993, from Hydro-punch 19, north of the intersection of Route 125 and Beardstown Road (Table 7 and Figure 6). The MCL for cis-1,2-DCE is 70 ppb, which is also the ATSDR comparison value (11). IDPH estimated the dose for children and adults to DCE through ingestion of groundwater and found the estimated dose did not exceed ATSDR health guidelines (12).

IEPA has reported low levels of cis-1,2-DCE in Beardstown public water supply well 13 since 1993 (15). Currently, well 13 (also G501 and municipal well 1) is not used as a drinking water source, but it is used for fire fighting and other emergencies (6). Groundwater modeling performed by IEPA predicts that contaminated groundwater flows beneath the off-site recovery well toward the Beardstown public water supply well field. The density of cis-1,2-DCE may be having an impact on the ability of the groundwater recovery system to remove it before it reaches the public supply well field; the trend appears to be an increase in cis-1,2-DCE levels in well 13. The highest level detected to date in finished or raw water samples is 7.4 ppb. That level of cis-1,2-DCE is less than the MCL, and exposure would not be expected to result in adverse health effects.

1,1 -Dichloroethene

The contaminant 1,1-DCE was detected in March 1998 in one off-site well in the farm field northwest of the site. The level detected (25 ppb) exceeds the MCL, but exposure at that level would not be expected to result in adverse, noncarcinogenic health effects. Exposure to that level, however, could pose a low increased cancer risk (16).

1,1-Dichloroethane

The highest level of 1,1-DCA detected following the 1983 groundwater investigation was 44 ppb. That sample was collected in December 1994 from monitoring well 901S immediately downgradient from the loading dock area (Table 8). No comparison value exists for 1,1-DCA in drinking water, but the estimated exposure to children and adults is less than NOAELs for 1,1-DCA in animal studies (17). Drinking water with that level of 1,1-DCA would not be expected to result in adverse health effects.


COMMUNITY HEALTH CONCERNS

Area citizens have expressed concern about the possible future contamination of the Beardstown public water supply wells. The Beardstown public water supply well field is approximately 2,000 feet northwest of the site, and groundwater flows in that direction. If contamination continues migrating in that direction, the wells might be at risk. The groundwater recovery and treatment system activated in 1997 should reduce the levels of contamination that might reach public water supply wells over time. Routine monitoring of public water supplies also aids in detecting contamination before water is distributed for use.

This public health assessment was made available for public comment from February 24 to March 29, 2000, at the Beardstown Public Library and on the IDPH home page. No public comments were received.


CHILD HEALTH INITIATIVE

IDPH and ATSDR recognize that children are especially sensitive to some contaminants. For that reason, IDPH includes children when evaluating exposures to contaminants and considers children as the most sensitive population considered in this public health assessment. At this time, no one is being exposed to contaminants migrating from the site.


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