SEATTLE — Washington state officials said Tuesday they found lower contamination levels when they tested geoduck clams than those alleged by China when it said geoduck imported from Puget Sound had high levels of arsenic.
China cited its findings in December when it imposed the largest ban on shellfish imports from Northwest waters — as well as from California and Alaska — in the region’s history.
Chinese officials said they found inorganic arsenic levels of .5 parts per million in the shellfish they tested in October.
But Washington officials’ tests produced different results.
“Only one of the whole samples was above China’s standard of .5 (parts per million) and everything else was below that, so that was good news,” said Dave McBride, who oversaw the testing at the Washington Department of Health.
The Department of Health tested more than 50 geoduck clams from the allegedly contaminated area, analyzing the different body parts of the clams to compare arsenic concentration levels.
The details of the test results are perhaps revealing than the overall “whole sample” figures. The skin of the clams tested by Washington exceeded China’s safe levels of inorganic arsenic by as much as three times, although McBride said that should not be worrisome to China, given how the Chinese consume geoduck clams.
“People generally do not eat the skin and we would advise people, when you eat geoduck, to remove the skin,” he said. “What we think is that, for the vast majority of the public, this is not a health issue at all. Obviously, when we’re talking about a carcinogen there is always the risk for high consumers.”
McBride added that the whole, or averaged samples, for several other clams came close to the .5ppm limit set by the Chinese.
The World Health Organization is said to be considering setting safe levels for inorganic arsenic in food in the .2-.3ppm range in 2014.
The shellfish that tested high for inorganic arsenic in China were harvested from a tract of land managed by the Department of Natural Resources that has since been closed. The tract is within the shadow of a copper smelter that was operated near Tacoma for 100 years.
“Well we know that arsenic levels are elevated in the surface soils in that area,” said Marian Abbett, manager of the Tacoma smelter clean up for the Washington Department of Ecology. Soil samples from the surrounding land show levels of arsenic between 40 and 200ppm, though that number does not directly equate to levels of arsenic that will end up in the water, or in shellfish.