Next year, Idaho health officials will check for high levels of lead in the blood of Silver Valley residents who live outside the Bunker Hill Superfund site.
The work will be done with a $130,000 federal grant, said Ken Lustig of the Panhandle Health District.
Samples of soil up and down the Coeur d’Alene River valley also will be taken, he said. That way, if high blood levels are found, health officials have an idea where the lead is coming from.
Lead can cause brain damage if it’s swallowed or breathed. Children are especially likely to be exposed to, and harmed by, the metal.
The highest blood-lead levels found among children in the United States were within the Superfund toxic waste site, where a now-defunct lead smelter spewed lead into the air in the 1970s.
Mine tailings are another source of lead. Dirt contaminated with metals continues to wash into the Coeur d’Alene River system from the historic mining area.
However, there is debate about whether the lead sulfides from ore are as easily absorbed into the body as the lead oxides from smelter emissions. If lead in the tailings isn’t readily absorbed, it could mean people who live away from the smelter are at less risk, even if they are exposed to high lead concentrations.
In the Kellogg area, residential yards were replaced with uncontaminated dirt if lead levels reached 1,000 parts per million. Lead levels of 5,000 ppm and higher have been found in riverbanks.
But people are less likely to be exposed to those rural “hot spots,” said Jerry Cobb of the Panhandle Health District.
“If you don’t have children living on that vertical river bank that’s 5,000 ppm, you don’t have a problem,” said Cobb.
“Just the fact that something’s there doesn’t mean it’s a problem. It has to get to you. With lead, and these other metals, you either eat it or breathe it.”
Valley residents could be exposed by eating vegetables grown in contaminated soil, breathing dust or drinking well water. The biggest concern is children playing in lead-tainted dirt.
The study will be designed this fall. Sampling probably won’t begin until next summer.
“We do sampling in the hottest, driest times of the year,” said Cobb, who supervises blood testing within the Superfund area. “We want to catch the kids when they’re truly outside doing what kids do, which is playing in the dirt and having fun.”
It will be 12 to 18 months from now before test results are available, Dobb said.
The grant is enough for one year’s sampling, said Lustig. The sample results will determine if additional tests are done.
The $130,000 grant was obtained from the state Division of Health, from the federal Agency for Substance and Toxic Disease Registry.
That agency helps pay for yearly blood-lead screening of children within the 21-square-mile Superfund site. Lead levels have dropped steadily over the last six years as yards and public areas have been cleaned up, Cobb said.
Lustig announced the latest grant at Wednesday’s meeting of the Coeur d’Alene Basin Interagency Group.
For seven years, that group of scientists has studied the effects of historic mining pollution on wildlife, water and land, and been involved in efforts to clean up potentially toxic metals. But they’ve wondered about humans, too.
“We’ve sampled the fish, we’ve sampled the swans, we’ve sampled the mink,” Lustig said. “And someone said, ‘What are the human health risks out there?”’