Harvard University Superfund Research Program (SRP) scientist Jim Shine, Ph.D. presented new information about lead, zinc, and cadmium in soils to community residents living around the Tar Creek Superfund Site in Oklahoma on May 9-10. Tar Creek is a 40 square-mile Superfund site contaminated with remains from what was once one of the largest lead and zinc mining operations in the world.
Shine introduced the key issue of bioaccessibility of metals, a measure of the potential for human uptake of toxic metals upon exposure. His study found the bioaccessibility of lead, zinc and cadmium in yard soils in the Tar Creek community varied greatly, from about 5 percent to 100 percent.
For risk assessment and clean-up purposes, the U.S. Environmental Protection Agency (EPA) often uses a fixed value of total amount of metals in soil to determine if a health risk exists and needs to be remediated. Shine explained that the total concentration of lead in the soil is not always the best way to think about health risks.
“The percent biologically available was not correlated with the total concentration, meaning that knowing the total concentration of metals didn’t always paint the best picture of true health risks,” said Shine. “My goal is to let them understand the assumptions that are happening underneath the risk assessments so that the community themselves can ask the right questions and understand the answers they get in return as the EPA selects clean-up options for their community.”
“I have consistently brought my SRP trainees to this community to talk about their research so they know how research actually relates to the real-world, answering real questions of concern from real citizens” said Shine. “Science is not limited to some assay in a test-tube in a laboratory with no windows.”
Shine began working in Tar Creek in 2004, studying the environmental pathways that determine how toxic metal mining wastes move through the environment and ultimately end up in people.