Two house painters in hazmat suits removing lead paint from an old house.
Two house painters in hazmat suits removing lead paint from an old house.

A discrepancy in two federal environmental standards regulating lead hazards in homes could put more than 35,000 children in the United States at an increased risk of lead poisoning, according to a new study led by Joseph Braun, an associate professor of epidemiology at Brown University. The U.S. Environmental Protection Agency (EPA) recently tightened the standard for the amount of residential dust lead considered hazardous to children to 10 micrograms per squre foot (μg/ft2) from 40 μg/ft2 on floors and to 100 μg/ft2 from 250 μg/ft2 on windowsills.

Traditionally, the residential standard had been the same as the clearance standard for dust lead levels after completing lead abatement work. However, despite a lawsuit filed by environmental groups in 2016, the EPA left the post-abatement clearance standard where it has stood since 2001. Both the residential standard and the clearance standard fall under the Toxic Substances Control Act.

As a result, a risk assessment could conceivably identify a dust lead hazard above 10 μg/ft2 but below 40 μg/ft2 on the floor of a home where there is a child with lead poisoning. According to Braun, an abatement contractor could theoretically do nothing, but given the discrepancy in the standards, the unit would pass the clearance standard.

Braun and his co-authors set out to determine how many extra cases of lead poisoning would result from the post-abatement clearance standard being higher than the dust lead hazard standard. The research, published in Pediatric Research, found that children in homes with floor dust lead loadings between 10 and 40 μg/ft2 had nearly four times the risk of lead poisoning compared with children from homes with floor lead dust loadings at or under 10 μg/ft2. The researchers estimated 36,700 cases of childhood lead poisoning were attributable to the regulatory discrepancy.

To conduct the study, the researchers analyzed 250 children from Cincinnati, Ohio, living in homes built before 1978 whose mothers participated in a longitudinal pregnancy and birth cohort study between 2003 and 2006. The researchers took samples of floor and interior windowsill dust lead loadings when the children turned 1 and again when they turned 2 while also collecting blood samples from the children.

The EPA has issued a proposed rule to align the post-abatement clearance standard with the tighter, revised standard from 2019. Its two-month public comment period ends August 24.

Reducing childhood lead exposure and addressing associated health impacts has been a top stated priority for the EPA, and in December 2018, the agency introduced its Lead Action Plan, a blueprint with the stated goals of reducing children's exposure to lead sources, identifying lead-exposed children and improving their health outcomes, communicating more effectively with stakeholders, and supporting and conducting critical research to inform efforts to reduce lead exposures and related health risks. The agency issued a status report update on the federal action plan in April 2019, highlighting activities being conducted to support the Lead Action Plan. In addition to highlighting ongoing efforts to strengthen the dust-lead hazard standards for floors and window sills, the status report also highlighted ongoing efforts to increase the number of certified renovation firms capable of providing lead-safe services.