Danger from arsenic in soil is unclear

April 21, 2007|By Rona Kobell | Rona Kobell,Sun reporter

Arsenic is an element found in the Earth that for centuries has been used as poison, pesticide and, in small doses, as a medicine.

When high concentrations are drunk or eaten, arsenic can cause cancer, nerve damage, heart disease and death, said Ana Navas-Acien, an assistant professor at the Johns Hopkins School of Public Health. "It was used as a poison because it has no smell or taste," she said.

But it's unclear whether a health risk is posed by prolonged exposure to arsenic in the soil, she and other experts said. Young children can ingest arsenic by getting their hands dirty and then putting them in their mouths.

But people playing baseball or football on a field contaminated with arsenic are unlikely to eat the carcinogen, researchers said.

The metal-based substance was found in the dirt at Baltimore's Swann Park, prompting the city to close the park, warn neighbors and call in federal health officials to investigate the health risk to the neighborhood.

Given all of the genetic and lifestyle factors that figure into a diagnosis of cancer, there is no way to say for sure whether arsenic contributed to the cancer of anyone who spent time at the park over the years, said Lynn Goldman, a pediatrician and environmental health professor at the Johns Hopkins Bloomberg School of Public Health.

Still, Goldman and other researchers say that closing the park was the appropriate action.

"Playing ball, I don't know how much exposure one would have," Goldman said. "We have seen some higher exposures in some communities. Those earlier cases tell us that, at least on a theoretical level, there's a reason for concern."

Ballplayers might have kicked up some dust sliding into home plate, and the dust might have stayed on their hands. If they then ate without washing their hands, they could have ingested arsenic, Goldman said.

Smokers could also ingest any dirt they picked up on their hands.

"It won't go down to your lungs," Goldman said, "but the dirt can get caught in your nose, and it will end up being swallowed that way."

A bigger concern would be children, who sometimes enjoy eating dirt and often put toys in their mouths that they have been playing with on the ground.

"Being that it's a park situation, it's doubtful that kids were out there every day," said Karl Markiewicz, a senior toxicologist with the Agency for Toxic Substances and Disease Registry, which is part of the federal Centers for Disease Control and Prevention. "But if some kid was out there every day, playing with his Tonka toy, there could be acute effects."

In some Asian countries, exposure to arsenic in drinking water has led to bladder and skin cancer, swelling of the face and cognitive delays in children.

In Taiwan, people who drank arsenic-laced water contracted what is known as "blackfoot disease," which causes the arteries to narrow and constricts circulation. It usually requires amputation.

But those illnesses are the result of prolonged, heavy exposure through drinking water, and no one who used the Baltimore park would face such risks, said Joseph Graziano, associate dean of research at Columbia University in New York.

"This possible intermittent exposure from soil doesn't compare with drinking arsenic in water, day in and day out," said Graziano, who has studied several cases of arsenic-related illness in Bangladesh.

In the Baltimore park situation, Graziano said, "I don't think it's fair to assume that there's an increased risk in cancer, for anybody."

There is some evidence that inhaled arsenic can injure pregnant women or their unborn babies, although the studies are not definitive, according to the U.S. Department of Health and Human Services.

Arsenic is not always harmful. It occurs naturally in licorice and often turns up in the soil at apple orchards, on golf courses and on land near copper mines. To mitigate, workers simply remove the top two inches of soil and put in clean fill, said Joshua Hamilton, director of the Center for Environmental Health Sciences at Dartmouth College.


Sun reporter Tom Pelton contributed to this article.

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