NATIONAL LEAD INDUSTRIES, INCORPORATED
PEDRICKTOWN (OLDMANS TOWNSHIP), SALEM COUNTY, NEW JERSEY
To determine whether residents living near the NLI site are exposed to contaminants, NJDHSS evaluates the environmental and human components that lead to human exposure. This pathways analysis consists of five elements: (1) a source of contamination; (2) transport through an environmental medium; (3) a point of human exposure; (4) route of human exposure; and (5) an exposed population. NJDHSS classifies exposure pathways into three groups: (1) "completed pathways", that is, those in which exposure has occurred, is occurring, or will occur; (2) "potential pathways", that is, those in which exposure might have occurred, may be occurring, or may yet occur; and (3) "eliminated pathways", that is, those that can be eliminated from further analysis because one of the five elements is missing and will never be present, or in which no contaminants of concern can be identified. Completed Exposure Pathway - Residential Soil
The human exposure pathway of concern to be evaluated is the ingestion of contaminated soils and dusts by children playing near the West Stream. The West Stream flows behind the residences located on Benjamin Green Road, and flows perpendicular to River Road. The lead contamination has posed a direct threat to residents, especially children, living near the stream. Approximately 10-20 persons are likely to be chronically exposed to site related contaminants through this pathway. Presently, all contaminated soils and sediments have been sampled and plans are ongoing for excavation and removal of contaminants, thus eliminating the source of contamination and interrupting the pathway for current and future exposure.
This section contains discussion of the health effects in persons exposed to specific contaminants (for completed pathways), health outcome data, and addresses specific community health concerns. Health effects evaluations are accomplished by estimating the amount (or dose) of those contaminants that a person might come in contact with on a daily basis. This estimated exposure dose is then compared to established health guidelines. People who are exposed for some crucial length of time to contaminants of concern at levels above established guidelines are more likely to incur associated illnesses or disease.
Health guidelines are developed for contaminants commonly found at hazardous waste sites. Examples of health guidelines are the ATSDR's Minimal Risk Level (MRL) and the USEPA's Reference Dose (RfD). When exposure (or dose) is below the MRL or RfD then non-cancer, adverse health effects are less likely to occur. MRLs are developed for each type of exposure, such as acute (less than 14 days), intermediate (15 to 364 days), and chronic (365 days and greater). ATSDR presents these MRLs in Toxicological Profiles. These chemical-specific profiles provide information on health effects, environmental transport, human exposure, and regulatory status.
Ingestion of contaminated soils remain a completed and potential human exposure pathway associated with the NLI site. Sample results of residential soils indicated the presence of lead contamination. Most of the surface soils samples collected from the adjoining properties to the West Stream indicated presence of lead below 500 ppm. However, some of the soils samples indicated presence of lead as high as 7180 ppm. These high concentrations of lead were detected at a depth of 0-1 feet (composite samples). Residential contact with sub-surface soil is not expected to occur, thus it is unlikely that residents will come in contact with the concentrations of lead indicated by the sampling.
The toxicological evaluation of the completed exposure pathway near the site is based upon an adult exposure duration of twenty-five (25) years, and a duration of ten (10) years for children.
In evaluating the toxicological significance of past exposure of adult residents to lead in surface soils, the following assumptions were made: a body weight of 70 kg and an ingestion rate of 100 mg/day. For children, the following assumptions were made: a body weight of 20 kg and an ingestion rate of 200 mg/day. Most of the surface soil samples collected at a depth of 0-3 inches from the adjoining properties to the West Stream indicated presence of lead below 500 ppm. Exposure dose calculations were based upon the maximum concentrations (500 ppm) detected in surface soils, thus representing a worse case exposure scenario. Lead
There is no current MRL or RfD for chronic oral exposure for lead. Inhaling or ingesting more than 500-1,000 micrograms of lead per gram of soil was a range previously considered by the CDC that could cause elevated blood lead levels in children. However, the CDC has since withdrawn this guideline due to the seriousness of lead exposure among children. Based on the assumptions cited above and the maximum levels of lead detected in surface soil samples near the site, the estimated exposure dose for children was below the No Observed Adverse Effect Levels (NOAEL) for chronic exposure in animals, for effects other than cancer as cited in the ATSDR Toxicological Profile for Lead. As previously stated, the Salem County Health Department performed lead screening for two children residing near site. The blood lead levels of the children exposed to site related contaminants were in the range of 3 to 4 ug/dl. The lead levels detected in their blood were not indicative of significant lead exposure, and not at the levels expected to cause adverse health effects.
The estimated exposure dose for adults was also below the No Observed Adverse Effect Levels (NOAEL) for chronic exposure in animals, for effects other than cancer as cited in the ATSDR Toxicological Profile for Lead. At such levels, non-carcinogenic adverse health outcomes among non-hypersensitive adults are not likely to occur. Lead is considered by the USEPA to be a probable human carcinogen. However, there are limited data describing the carcinogenicity of lead in humans. A cancer slope factor for lead has not been established; lifetime excess cancer risk estimates could not be calculated at this juncture.