What’s on the surface is often at odds with what’s buried beneath. That might seem pretty obvious, but the R.I. Department of Health does not require lead contamination soil sample to look below the surface. As it turns out, higher lead concentrations often lurk deeper down, Brown researchers report. The recent findings are important because lead exposure has serious health consequences, especially for children, researchers say.
“Especially when you are talking about children’s health and the health of the people who live there, one mistake is one too many,” lead author Marcella Thompson said in a press release. “Better safe than sorry. If there is a potential for [misclassification] to occur, we should take the more conservative route.”
The researchers analyzed hundreds of soil samples collected from 31 lead-painted water tower sites in southern Rhode Island and found that solely testing at the surface would have overlooked higher lead concentrations at lower depths at four of the 31 properties. Just six to 12 inches beneath the surface, higher than “lead-safe” concentrations of lead laid low. Sampling at just the surface could have led to 13 percent of the sites being misclassified as “lead-safe,” as defined by the DOH.
The researchers conducted the study at the DOH’s request as part of efforts to assess the impact of the state’s lead-painted water towers. The practice of coating towers with lead-paint stopped in 1979, but since then some of the paint has flaked off and contaminated nearby properties. In 2004, residents near a water tower in Westerly raised concerns about soil sampling methodology. The proceeding investigations uncovered differences in the testing standards of the Department of Health and the Rhode Island Department of Environmental Management: the latter requires testing below the soil surface while the former does not.
The findings of the study, reported in the journal Science of the Total Environment, affirm the DEM’s methodology. The study suggests that the DOH consider revising its rules and regulations for the prevention of lead poisoning. It recommends that soil be sampled at several depths and farther away than 200 feet.