Watch out: That clam just might kill you

VICTORIA BARBER

May 16, 2008 at 8:13AM AKST

In February, the Division of Public Health released its assessment of the toxins that have lingered in Unalaska beaches since the Selendang Ayu oil spill in 2004.

This review is likely to be the last because, according state toxicologist Lori Verbrugge, "we really didn't find anything of concern."

Not in relation to the spill, anyway.

Verbrugge said the follow-up study revealed that levels of the cancer-causing PAHs had declined to the point that they no longer constituted a health risk. But she discussed the State's concern about something even more disturbing than oil-tainted seafood. High levels of the naturally occurring toxins that cause Paralytic Shellfish Poisoning, or PSP, have been found in blue mussel samples taken from around the island.

“It’s a big concern, and the real worry in eating shellfish,” Verbrugge said. “(Eating) high levels of PSP can kill you the same day."

Verbrugge’s study was a follow-up to one performed in 2005, which tested a variety of substances, from harbor seal blubber to roe to the island’s abundant bivalves. Initially, scientists were looking for chemical compounds called polycyclic aromatic hydrocarbons, or PAHs, which are in oil and known to be carcinogenic.

Testing showed high levels of PAHs in only one type of sample, blue mussels, so the department targeted that species when they returned in 2006. While they were at it, they decided to test for PSP as well.

“People don’t want to eat oil, and they’re mad that it’s out there — understandably so,” Verbrugge said. “But the risks that people are concerned with aren’t really the risks that us as toxicologists are worried about, and this was a great example.”

PSP is a natural occurrence, caused by algal blooms known as “red tide.” These blooms create an area of toxic, microscopic algae. When shellfish, which are filter feeders, store the toxins they become poisonous to mammals.

That’s bad news for anyone who likes to gather their own seafood. PSP is extremely dangerous to humans and can cause disorientation, numbness, paralysis or death.

Verbrugge and her colleagues collected samples for analysis of blue mussels from Makushin Bay, North Scan Bay, South Scan Bay, Kashega Bay, Wide Bay, Volcano Bay and Kismaliuk Bay.

Eight of the 10 samples tested positive for PSP. Two samples had such high levels of PSP that they were “bad enough that you would stop breathing and die,” Verbrugge said.

Harvesting from uncertified beaches appears to be getting even riskier. Bruce Wright, senior scientist with the Aleutian Pribilof Islands Association, has been studying PSP levels throughout the Aleutians for the past year. He said that there is no data to confirm it, but it seems that PSP seems to be on the rise.

“Every time I give a talk in the Aleutians (about PSP), everyone in the audience say ‘Dude, either I’ve had those symptoms or I know someone who has,’” said Wright. “I used to think the Bering Sea was PSP free.”

Scientists have speculated that climate change might be one factor. As ocean waters become warmer they may create a more hospitable environment for algal blooms and increase the frequency of PSP.

Wright said that while PSP data is being collected in light of climate change, it’s too early to verify a trend. However, Native elders have told him that PSP is a worse problem than it used to be.

Blue mussels and butter clams are considered to be the most dangerous. Butter clams have been known to retain toxins for up to two years after a red tide.

“Every test I’ve ever run for King Cove butter clams has been positive,” Wright said.

Littleneck clams are considered to be less dangerous because they process the toxins more quickly.

Shellfish sold in stores or restaurants are safe to eat because they are from beaches that have been tested and certified to be PSP free. However, none of the beaches in Unalaska undergo testing, and all are presumed to be dangerous for harvesting.

David Gregory has lived in Unalaska since 1975. He said that since the Selendang Ayu, people are more nervous about eating clams and other shellfish. Nevertheless, some still harvest it.

“When the weather’s good, people go out in their boats and get what they can to supplement their diets,” said Gregory, who said he sometimes eats local shellfish himself. “There is a saying that ‘when the tide goes out, the table’s set.’”

Gregory said that there is concern in the community that the dangers of PSP are killing a part of the Unangan way of life.

“Subsistence use of tidal resources is being lost, and it’s an issue that people are trying to figure out ways to work around,” Gregory said.

Gregory said that he hopes that soon there will be a test for PSP made available to communities like Unalaska, so that residents and subsistence users can once again comb the beaches for dinner without fear.

Wright said that such a test might someday be available. He said that, in the meantime, people will continue to risk it to pick clams and mussels.

“It’s a fun and social event for everyone who does it, and it’s healthy except that it can kill you,” Wright said. “Some people like to play Russian roulette.”

Victoria Barber can be reached at (907) 348-2424 or toll free at (800) 770-9830, ext. 424.