A new study led by biochemist Gabriel Filippelli at Indiana University found that approximately one in four U.S. households have soil exceeding the new U.S. Environmental Protection Agency’s lead screening levels of 200 parts per million (ppm), which was halved from the previous level of 400 ppm. For households with exposure from multiple sources, the EPA lowered the guidance to 100 ppm, and nearly 40% of households exceed that level. The findings were published in GeoHealth, an AGU journal that focuses on the intersection of human and planetary health.
Lead is a heavy metal that can accumulate in the human body, causing toxic effects, especially in children. Historically, lower-income communities and communities of color have been disproportionately affected by lead exposure due to redlining and discriminatory practices. Most lead exposure today comes from contaminated soils and dust, even after lead-containing infrastructure has been removed. The Centers for Disease Control and Prevention has lowered the lead concentration limit in blood several times and currently set it at 3.5 micrograms per deciliter.
The study authors noted that the lag in updating the EPA’s soil lead screening level for over 30 years is likely due to the immense and ubiquitous nature of the problem. The recent lowering of the screening level presents a significant challenge in terms of the nation’s lead and remediation efforts. Using a database of residential soil samples, the researchers found that about 25% of the samples exceeded the new 200 ppm level, indicating that roughly 29 million households are affected.
To address the issue of lead-contaminated soils, traditional methods like “dig and dump” soil removal can be costly and time-consuming. A more cost-effective option is capping, which involves burying the contaminated soil with a foot of clean soil or mulch. This method is quicker and can reduce exposure immediately without waiting for a lengthy remediation process. Capping is being used by urban gardeners with raised beds to address concerns about the history of land use at their properties.
Despite the scale of the problem, Filippelli remains optimistic about addressing lead contamination as it is a solvable problem. He believes that taking action and implementing simple remediation methods like capping can significantly reduce exposure to lead. Moving forward, research will focus on understanding the lifespan and sustainability of capping to further improve remediation efforts. Overall, by raising awareness about lead contamination and implementing practical solutions, the health benefits for affected households can outweigh the costs and efforts associated with remediation.