Get the Lead Out: The Persistent Problem of Lead Exposure from Soil, Dust and Water
Citation:
Hughes, M. AND K. Bradham. Get the Lead Out: The Persistent Problem of Lead Exposure from Soil, Dust and Water. Society of Toxicology, San Antonio, Texas, March 11 - 15, 2018.
Impact/Purpose:
This is the proposed presentation description or abstract for a workshop to be presented at the 2018 Annual Meeting of the Society of Toxicology. The purpose is to present data on the exposure of lead in soil, dusts and water, neurotoxicological effects of lead and modeling efforts aid in predicting blood lead levels following exposure by soil or water.
Description:
The heavy metal lead, a known neurotoxicant, has been used for centuries in a variety of industries and household and consumer products. The choice to use lead reflects its physical/chemical properties including softness, ductility, poor conductibility and resistance to corrosion. Although a natural component of the earth’s crust, high concentrations of lead in the environment, particularly soil, have resulted from human activity and its resistance to natural degradation. From the decades long use of lead as a fuel additive, soils in urban areas with high traffic volume have been found to have highly elevated levels of lead. In residences that predate 1978, when lead-based paint was banned in the United States, dust from deteriorating paint contains elevated levels of lead. The soils on and near several industrial smelting sites, such as in East Chicago, IN, also have high levels of lead. Finally, lead is found in drinking water in homes that have water pipes containing lead, with leaching a complex function of pH, alkalinity, and water characteristics. In homes typically located in older urban centers with aging water infrastructure, the risk of elevated lead in the water is higher, if the water is corrosive. Elevated blood levels have been found in people, particularly children, who were exposed to soils, dust, and water containing high levels of lead. The main public health issue with lead is that it is neurotoxic, especially to children. Elevated levels of lead in children can result in impairment of intelligence and learning, and behavioral disorders. There is no known biological requirement for lead, although it is absorbed fairly well following ingestion or inhalation. Lead accumulates in bone, as it has similar properties as calcium, taking its place in this organ. Lead in bone can be a long-term source of internal exposure, as it can be released from bone into the systemic circulation and distributed to other organs. This panel brings together experts on lead with regard to its exposure, neurotoxicological effects, and the use of models to predict blood lead levels in individuals exposed to lead in soil, dusts, and water. The first presenter will discuss the positive association between lead in soil or bioaccessible (an in vitro method simulating the gastrointestinal tract) lead and blood lead levels in children in an urban area. This presentation shows the feasibility of using in vitro methods to improve child lead risk assessments in the place of total soil lead content. The second presentation will discuss how soil lead levels and children’s blood levels have changed pre- and (10 years) post-Hurricane Katrina in New Orleans, Louisiana. It was observed with decreased soil lead levels after hurricane, the blood lead levels in the children also decreased. The third presentation will focus on the potential mechanisms of lead that result in adverse health outcomes following maternal lead exposure with the potential development of neurotoxicity in the offspring. This includes studies from both human and laboratory maternal exposures. The fourth presentation will evaluate the impact of varying Regional Screening Levels on blood lead predictions in the Integrated Exposure Uptake Biokinetic (IEUBK) model to aid in reducing uncertainty in human health risk assessments. The final presentation will describe application of EPA’s Stochastic Human Exposure and Dose Simulation-Multimedia and IEUBK models to determine the level of lead in drinking water that should result in children’s blood lead levels that are less than specified values. The analysis reveals the importance of the soil and dust ingestion exposure pathway. (This abstract does not represent US EPA policy.) (note - the number of characters in the presentation description exceeds what is allowed in this box. One sentence is missing. See attached