Arsenic found in soil samples

E-mail this article Print this article

Sampling of 62 of 75 wooded sites on the mainland of South King County revealed elevated concentrations of arsenic in soil — enough, health officials say, to pose a health risk to residents who don't take simple precautions.

But even though levels of contamination exceeded state limits in several areas, there's no reason for residents to be alarmed, officials said.

"This is not an imminent health threat," said Alonzo Plough, director of Public Health — Seattle & King County. "This is not like discovering E. coli or some hazard where we have any evidence that there's even been human exposure.

"We have no findings of health effects."

State Department of Ecology officials have been sampling soil in an ever-widening footprint spreading north, east and south of the former Asarco smelter off Commencement Bay in Ruston, near Tacoma. Two years ago, they found elevated levels of arsenic and lead on several sites throughout Vashon and Maury islands.

The copper smelter operated from the 1890s to 1985.

The latest samples, taken over 200 square miles from Federal Way north to West Seattle and as far east as Bellevue, showed arsenic levels significantly lower than those found on Vashon and Maury, but still above state cleanup limits of 20 parts per million. Only six sites showed levels above 100 parts per million in soil.

One, near Normandy Park, was 260 parts per million, slightly higher than the 230 parts per million level at which the federal government required yard replacements near Ruston.

Lead in soil was far less widespread. Lead levels above state standards were found on only 12 of 75 sites.

State officials think the contamination is linked to emissions from Asarco's smelter and that the contaminants settled into the soil over the years. Once the top 2 to 6 inches of dirt have been turned over, the contamination is diluted with fresher soil from below.

In other words, on property that has been disturbed or replaced — with homes, businesses, yards — contamination levels typically drop. The recent samples were all taken from areas where dirt has remained untouched for years.

Precautions against arsenic in soil • Don't wear your shoes into the house. Most dirt enters the house on shoes. • Wash your hands frequently, especially before eating. • Damp-mop floors frequently to keep the dust down — especially if you have small children. • Keep children out of bare patches of dirt. Cover with grass or plants, or fence off such areas. • Wash vegetables and fruits before eating. For more information, go to: www.metrokc.gov/health/tsp/arsenic.htm

"The 75 sites were all in what we call minimally disturbed areas," said Norm Peck, manager for the smelter-plume contamination program in King County. "Most, if not all, were in wooded areas clearly not disturbed in at least 20 years."

Arsenic occurs naturally in the Northwest, but exposure to elevated levels has been linked to more than 30 health problems, from abnormal heart functions to blood vessel damage. It's also been linked to increased risk of kidney, liver, bladder and skin cancers.

While scientists generally agree that ingesting arsenic at any level is not good, the risk is based on statistics and direct exposure over a lifetime. And arsenic, like lead, is fickle; sensitivity varies from person to person.

Take the state's cleanup limit of 20 parts per million, for example. With exposure over 70 years to 20 parts of arsenic to a million parts of soil, officials would expect to see one additional cancer death for every million people.

"This is not a health emergency," said Marian Abbett, who oversees the Department of Ecology's smelter-contamination response program. "There is a concern, but there are measures people can take."

The federal Environmental Protection Agency (EPA) does not have a uniform national standard for arsenic limits in soil.

At the Ruston site, where hundreds of homes were exposed to high levels of arsenic contamination, The EPA required yard replacement only when arsenic reached 230 parts per million, a level of risk at which one of every 2,000 people exposed over a lifetime could expect to die from cancer.

Typically, however, federal cleanup sites range from two to 305 parts per million.

Regardless, for arsenic to do damage it must be inhaled or ingested over long periods.

"That's why our concern is with children because they're in direct contact with soil when they play," Abbett said. "Adults could be exposed working in a garden, or not washing vegetables thoroughly. We also recommend people don't smoke while working in dirt" because arsenic could be inhaled with the smoke.

Next summer, the state plans to take more detailed samples around day-care centers and other children's play areas in mainland King County to make sure soil samples don't exceed 100 parts per million — the level at which the state says immediate corrective action is warranted.

When similar tests were performed on 34 play areas of Vashon and Maury islands — where elevated lead and arsenic levels were significantly higher — no children's play areas tested exceeded those levels.

The Ecology Department is still studying the depth and magnitude of the contamination and will begin collecting soil samples this spring in Pierce County.

But it remains unclear how much cleanup will take place.

"Right now we're just figuring out how big it is, how bad it is and what people can do to reduce risks," Peck said.

Craig Welch can be reached at 206- 464-2093 or cwelch@seattletimes.com. Seattle Times staff reporter Andrew Garber contributed to this report.