Sick soil in C.R.

CEDAR RAPIDS - Chemicals banned decades ago persist in soil throughout the city, but experts are divided on the risk they pose to people living in Cedar Rapids.

“There's a fairly big gap in our knowledge,” said Hans-Joachim Lehmler, associate professor of occupational and environmental health at the University of Iowa College of Public Health. “Will someone immediately get sick? Probably not. Is there a long-term effect from these chemicals? We don't have an answer.”

Polychlorinated biphenyls, or PCBs, and chlordanes, both banned from use by the U.S. Environmental Protection Agency, were found in nearly all of the soil samples collected during a University of Iowa study. Lehmler, a chemical toxicologist, did not participate in that study, but reviewed the report for The Gazette.

Chlordane can affect the nervous and digestive systems and the liver, with exposure to large amounts leading to convulsions and death, according to the Agency for Toxic Substances and Disease Registry.

Exposure to PCBs can cause cancer. Children whose mothers were exposed to large amounts before and during pregnancy can be born at low birth weights and experience motor skills problems and other developmental delays.

While Lehmler could not rule out the possibility of long-term effects, Stuart Schmitz, environmental toxicologist with the Iowa Department of Public Health, said concentrations found by the researchers are not cause for concern.

“With the levels they found, there wouldn't be any risk at all,” Schmitz said.

The UI team sampled soil in residential areas of Cedar Rapids in August 2008, two months after floodwaters inundated the city.

Principal investigator Keri Hornbuckle said she was interested in seeing the effects of the flood on chemical concentrations in her hometown.

“We chose Cedar Rapids because I know the city,” said Hornbuckle, a 1983 Washington High School graduate, now a UI professor of civil and environmental engineering.

Researchers took 66 samples from public right of way covering nearly four miles in the city, concentrating on sites west of the Cedar River and south of Cedar Lake, which is known to have been polluted with PCBs and chlordanes. They also took samples outside of flooded zones.

Hornbuckle said results, published online in the journal Environmental Pollution, showed concentration levels similar both in and outside the flooded areas.

“We found these two sets of chemical groups in almost every sample,” she said.

Chlordane, banned by the EPA in 1988, was used for termite control and as an insecticide on lawns, gardens and corn and other crops, while PCBs, banned in the late 1970s, were widely used as coolants, in electrical transformers and in a wide variety of products such as paints and pesticides.

Hornbuckle said the distribution of chlordanes could reflect places where Cedar Rapids residents used the pesticide.

She noted that PCBs are ubiquitous in the environment and can spread through various means, such as becoming airborne in dust.

The study is one of very few conducted on chlordanes and PCBs in urban residential soils in the United States, Hornbuckle said, and possibly the only one from the last two decades.

Concentration levels compare to urban studies elsewhere in the world, she said, but are higher in Cedar Rapids than those from rural studies.

Both chemicals are slow to degrade, but experts believe concentrations are dropping since the chemicals were banned.

“The values are not as high as if we'd done the same study 40 years ago,” Hornbuckle said.

Bob Drustrup, environmental engineer with the Iowa Department of Natural Resources, said few sites in Iowa have been targeted for cleanup because of contaminations by PCBs or chlordane.

“Close to zero,” he said.

Like Schmitz, Drustrup said he found nothing alarming with the chemical levels reported in the UI study.

Residents could be affected if exposed to higher concentrations on their skin or children could be at risk if they ingest the soil in large amounts, he said.

The study showed chlordane concentrations ranged from 0 to 7,500 parts per billion, below the statewide standard of 8,100 parts per billion, while PCB levels were 3 to 1,200 parts per billion, under the 2,200 parts per billion limit that requires remediation.

Drustrup noted that the state monitors the chemicals in fish and provides advisories as warranted on fish consumption, a more common route of exposure than soil.