The U.S. Food and Drug Administration says consumers should avoid consuming shellfish from Oregon and Washington states because it may be contaminated with toxins that cause paralytic shellfish poisoning. At least 31 people have fallen ill in Oregon so far, according to health officials. Here's what you need to know about the federal agency's advisory.
The warning says to avoid oysters and bay clams harvested since May 28 in Netarts and Tillamook bays in northern Oregon, as well as shellfish harvested since May 26 in areas around Willapa Bay in southern Washington. They may be contaminated with high levels of paralytic shellfish poisoning, or PSP, a naturally occurring toxin produced by algae.
Shellfish harvested from those areas during that period was distributed beyond Oregon and Washington to Arizona, California, Colorado, Hawaii, Nevada and New York. The FDA has warned restaurants and retailers in those states not to serve it.
Elevated levels of toxins were discovered in shellfish on the Oregon coast for the first time on May 17, state fish and wildlife officials said.
Since then, an outbreak of crippling shellfish poisoning has sickened at least 31 people in Oregon, according to the Oregon Health Authority. The agency has asked people who have harvested or eaten Oregon shellfish since May 13 to complete a survey intended to help investigators identify the source of the outbreak and the number of people sickened.
Oregon authorities have closed the state's entire coastline to the harvest of mussels, razor clams and bay clams. Agriculture officials also closed three bays, including those mentioned in the FDA advisory, to commercial oyster harvesting.
Officials in neighboring Washington have also closed the state's Pacific coast to harvesting shellfish, including mussels, clams, scallops and oysters, according to a shellfish safety map produced by the Washington State Department of Health.
Paralytic shellfish poisoning, or PSP, is caused by saxitoxin, a naturally occurring toxin produced by algae. Saxitoxin is a neurotoxin, meaning it can damage nerve tissue.
People who eat shellfish contaminated with high levels of saxitoxins usually start feeling sick within 30 to 60 minutes, according to Oregon health officials. Symptoms include numbness of the mouth and lips, vomiting, diarrhea, shortness of breath, and in severe cases, an irregular heartbeat.
According to the health department, there is no antidote for PSP. Treating severe cases may require mechanical ventilators to assist breathing.
Authorities warn that cooking or freezing contaminated shellfish does not kill the toxins or make it safe to eat.
A “very large” algae 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 at a briefing.
The toxins have built up in the shellfish, making some people who have eaten them sick.
Although the factors that cause 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.
“Research shows that many algae species flourish when wind and water currents are favorable,” says the agency on a web page dedicated to explaining harmful algal blooms. Some blooms result from “slow water circulation, unusually high water temperatures and extreme weather events such as hurricanes, floods and drought.”
According to the agency, algae growth can also increase if nutrients used in fertilizers, mainly phosphorus and nitrogen, enter water bodies.
Officials in Oregon said it could take weeks, months or even a year for toxin levels to drop, depending on the type of shellfish.
Mussels can accumulate paralyzing shellfish poison quickly, but they can also get rid of it quickly, said Hunter, the Oregon fish and wildlife official. Because of this, it can take two weeks to a month for mussels to remove the poison.
However, razor blades do this more slowly. It can take several months to a year for them to cleanse themselves due to current high toxin levels, Hunter said.
Such high levels of paralyzing shellfish poison have not been seen in Oregon in decades, according to Hunter, who cited a previous closure of the state's shellfish harvest in 1992.
However, PSP has been widespread in regional waters for centuries, he said.
The harvest closure could be a blow to fisheries in the Pacific Northwest.
According to the National Oceanic and Atmospheric Administration, the shellfish industry generates $270 million annually for the region's economy and employs about 3,200 people.
