PORTLAND, Ore. The U.S. Food and Drug Administration says consumers should avoid eating shellfish from Oregon and Washington state because they may be contaminated with toxins that cause paralyzing shellfish poisoning. At least 31 people have fallen ill in Oregon so far, according to state health officials. See what you should know about the federal agency’s advice.
The warning says to avoid oysters and clams harvested from Netarts and Tillamook Bays in northern Oregon since May 28, as well as shellfish harvested from areas around Willapa Bay in southern Washington since May 26. PSP, a natural toxin produced by algae.
Shellfish harvested from these areas during this period were distributed beyond Oregon and Washington to Arizona, California, Colorado, Hawaii, Nevada, New York. The FDA has warned restaurants and retailers in those states not to serve it.
Elevated levels of toxins were first detected in shellfish off the Oregon coast on May 17, state fish and wildlife officials said.
Since then, an outbreak of paralytic shellfish poisoning has sickened at least 31 people in Oregon, according to the Oregon Health Authority. The agency asked people who gathered or ate Oregon shellfish since May 13 to fill out a survey designed to help investigators identify the cause of the outbreak and the number of people sickened.
Oregon officials have closed the state’s entire coast to harvesting mussels, razor clams and clams. Agricultural authorities also closed three bays, including those mentioned in the FDA advisory, to commercial oyster harvesting.
Authorities in neighboring Washington have also closed the state’s Pacific coast to shellfish harvesting, including mussels, clams, scallops and oysters, a shellfish safety map produced by the Washington State Department of Health shows.
Paralytic shellfish poisoning, or PSP, is caused by saxitoxin, a natural toxin produced by algae. Saxitoxin is a neurotoxin, which means it can damage nerve tissue.
People who eat shellfish contaminated with high levels of saxitoxins usually begin to feel sick within 30 to 60 minutes, according to Oregon health officials. Symptoms include numbness in the mouth and lips, vomiting, diarrhea, shortness of breath, and irregular heartbeat in severe cases.
There is no antidote for PSP, according to the health agency. Treatment for severe cases may require mechanical ventilators to aid breathing.
Authorities warn that cooking or freezing contaminated shellfish does not kill the toxins or make them safe to eat.
A “very large” algal bloom has resulted in “unprecedented levels” of PSP toxins along the Oregon coast, Matthew Hunter, shellfish program manager for the Oregon Department of Fish and Wildlife, said during a briefing.
Toxins built up in the shellfish, sickening some people who ate them.
Although the factors that create harmful algal blooms are not well understood, certain factors — resulting from both natural processes and human activities — are believed to play a role, according to the National Oceanic and Atmospheric Administration.
“Studies show that many species of algae bloom when wind and water currents are favorable,” the agency says on a web page dedicated to explaining harmful algal blooms. Some blooms, it says, result from “slow water circulation, abnormally high water temperatures and extreme weather events such as hurricanes, floods and droughts.”
Algae growth can also increase when nutrients used in fertilizers, particularly phosphorus and nitrogen, flow into bodies of water, according to the agency.
Oregon officials said it could take weeks, months or even a year for toxin levels to decrease, depending on the type of shellfish.
Mussels can accumulate paralyzing shellfish poison quickly, but also get rid of it quickly, according to Hunter, Oregon’s fish and wildlife officer. Because of this, it can take two weeks to a month for the mussels to eliminate the toxin.
Razor clams, however, are slower to do this. It may take several months to a year to purify themselves due to current high levels of toxins, Hunter said.
Such high levels of paralyzing shellfish poison have not been detected in Oregon for decades, according to Hunter, who cited a previous closure of shellfish harvesting in the state in 1992.
However, PSP has been prevalent in regional waters for centuries, he said.
The harvest shutdown could be a blow to fisheries in the Pacific Northwest.
The seafood industry generates $270 million a year for the region’s economy, according to the National Oceanic and Atmospheric Administration, and employs about 3,200 people.
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