CHESTNUT STREET PROPERTY NEAR ABEX LEAD SITE
The U. S. Environmental Protection Agency - Region III (EPA) asked the Agency for Toxic Substances and Disease Registry (ATSDR) to assess the health impact of lead contamination in soil at a private home near the Abex Corporation site in Portsmouth, Virginia. The EPA also asked ATSDR to comment on the utility of indoor dust sampling for the assessment of the health risk to occupants of the house.
The Abex Corporation operated a brass and bronze foundry from 1928 to 1978. When the facility was operating, air particulates from the stack were dispersed to the surrounding neighborhoods.In 1991, the potentially responsible party conducted a remedial investigation at the site with oversight by the Virginia Department of Waste Management and the EPA. In this study, transects were drawn though off-site areas in the predominant wind directions as predicted from wind rose data. Soil samples were collected from residential properties along the transects and analyzed for lead and other metals. A surface soil sample collected from a property on Chestnut Street contained 33,700 parts per million (ppm) lead.December 1997, the EPA collected and analyzed six additional surface soil samples at this property; the lead concentrations in these samples were 4,043; 349; 874; 1,670; 359; and 5,543 ppm. Two adults and three teen-aged children currently live at this property. The property is located about 1,500 feet southwest of the former Abex Foundry.
Lead is toxic to the nervous system, particularly in young children and in a developing fetus. Epidemiologic studies have provided evidence that neurotoxic effects of lead can occur at blood lead levels as low as 10 µg/dl. Children are also at greater risk from environmental lead contamination, because they are more likely to engage in hand-to-mouth activity that could increase exposure.
Recent studies indicated that surface soil at the Chestnut Street property contains lead at conentrations as high as 5,543 ppm. This contamination is of health concern as epidemiologic studies have indicated that blood lead levels can increase in children who are exposed to soil containing lead at concentrations of 500 to 1,000 ppm.
Residents could also be exposed to lead from indoor house dust. It has been estimated that about 50 percent of the mass of house dust is derived from soil. Therefore, if residential soil contains elevated concentrations of lead, dust inside the house could also be contaminated. To assess indoor dust contamination, two complimentary methods are used: (1) measuring the lead concentration in dust (ppm) and (2) measuring lead loading on surfaces (micrograms/square foot).
To assess the health impact of lead-contaminated house dust, risk assessors often apply soil lead criteria (e.g., lead concentrations in excess of 500 ppm pose a potential health risk). For lead surface loading, the U. S. Department of Housing and Urban Development (HUD) has recommended guidelines for indoor residential surfaces -- e.g., 100 micrograms (µg) /square foot for floors. However, the HUD guidelines are based on what is practical to achieve following lead-paint abatement, and the guidelines< are not health-based. Recent studies have indicated that blood lead levels can be elevated in some children at surface loading levels below the HUD guidelines.
Lead concentrations in house dust and lead surface loading provide complimentary information. The risk assessor should consider not only the lead concentration in dust, but also how much dust is present on the surface. Therefore, if house dust testing is conducted, both parameters should be included.
- Lead contamination in surface soil at the Chestnut Street property poses a public health hazard.
- Lead contamination inside the house has not been characterized.
- Remediate lead contamination in soil at the Chestnut Street property.
- Characterize lead contamination in house dust to determine if indoor remediation is needed.