Oregon issues clam eating limit due to high arsenic levels

Oregon health officials on Monday issued a consumption advisory for softshell clams dug along the state's entire coast because they contain high levels of arsenic.

The Statesman Journal reported on the problem last week, after the Oregon Health Authority notified coastal health and government officials, but told them to keep mum.

Several refused, saying the public deserved to know right away.

"The fact we're being asked to sit on information that's a matter of a public health advisory – I didn't really feel comfortable doing that," Newport City Councilor David Allen said.

The advisory recommends removing the skin from the siphon, or neck, of softshell clams before eating them, because that's where most of the arsenic is concentrated.

It also recommends limiting the amount consumed each month, depending on the eater's age and where the clams were harvested.

OHA has declined to release information about the arsenic levels.

But the Statesman Journal obtained a technical advisory showing that levels along the North coast were highest, with an average of 4.87 milligrams per kilogram of tissue. The Mid-Coast followed at an average of 1.39 mg/kg, and the South Coast had the least, at 0.77 mg/kg.

The U.S. Environmental Protection Agency sets safe levels at than 0.7 mg/kg of tissue or less.

The state Department of Environmental Quality found elevated arsenic levels in samples of softshell clams taken in 2013 as part of its water quality toxics monitoring program.

OHA received the results in March of this year and confirmed them with follow-up sampling conducted in April. It received those results in May and finished its analysis of health risks in June.

The advisory targets recreational clam diggers and the specific species Mya arenaria. That species is not commercially available in markets or restaurants, OHA said in a press release.

DEQ also tested Olympia oysters, California mussels and purple varnish clams, looking for a wide range of potential contaminants, including other metals such as cadmium, mercury, and selenium; chlorinated pesticides such as DDT and chlordane; polychlorinated biphenyls (PCBs); dioxins and furans; tributyl tin; and brominated flame retardants (polybrominated diphenyl ethers, or PBDEs).

None of the other contaminants were present at high enough concentrations to pose a public health risk, OHA said in a question and answer document made public Monday.

The clams are contaminated with inorganic arsenic, the toxic form of arsenic. It can occur naturally but also can be introduced by pressure-treated wood, outdoor materials, agriculture and industry.

The advisory is likely to be permanent, OHA said.

Chronic exposure to inorganic arsenic can increase the risk of skin, bladder, liver and lung cancer. Chronic exposure can also cause wart-like skin problems, increase the risk of diabetes and cardiovascular problems, and cause neurological problems including painful numbness or "pins and needles" sensations in toes and fingers.

tloew@statesmanjournal.com, (503) 399-6779 or follow at Twitter.com/Tracy_Loew