|
|
|
|
News
|
|
|
|
ODA program keeps an eye on shellfish toxins
|
|
|
6/1/2011
|
|
Article Content Year around monitoring maintains food safety
One of the more popular times to harvest shellfish on the Oregon Coast can also be the most dangerous. Summer brings ideal weather and tidal conditions for recreational harvesting of clams and mussels, but can also bring high levels of harmful bacteria and toxins in the bays and estuaries, and on beaches and jetties. Oregonians should know that someone is watching out for them. The Oregon Department of Agriculture's Shellfish Program provides year around sampling and testing to protect the public and the commercial shellfish industry. As summer approaches, a strong monitoring effort is needed if the presence of marine toxins rises.
"Recreational shellfish harvesting is popular in Oregon," says Vance Bybee, administrator of ODA's Food Safety Division. "But in the summer, there are often problems associated with algae blooms in the ocean which could cause problems in shellfish that cooking can't eliminate."
From the coastline to its laboratory in Portland, ODA ensures safe consumption of commercially and recreationally harvested shellfish. ODA may double or even triple shellfish sampling and testing during summer as warmer water causes toxic algae blooms where clams, mussels, and oysters feed.
"The two marine toxins of most concern for us are paralytic shellfish toxin (PST) and domoic acid," says Alex Manderson, ODA's Tillamook-based shellfish specialist. "PST is still a concern in the summer months, but historically not as much as domoic acid, which often forces harvest closures between spring and fall. With more daylight hours available for clam diggers and other shellfish harvesters, it's very important for us to know what's going on in the ocean and along the coast."
Eating shellfish contaminated with low levels of domoic acid can cause minor illness within minutes to hours after consumption. In mild cases, symptoms can include vomiting, diarrhea, abdominal cramps, and headache. More severe cases of domoic acid poisoning can result in memory problems, damage to the central nervous system, renal failure, and even death. Young children, pregnant women, and the elderly are especially vulnerable to the effects of domoic acid poisoning. Anyone experiencing such symptoms after consuming shellfish should contact a physician.
Razor clams are affected by domoic acid to a greater extent since the toxin can be stored in the fatty, edible tissue. While other shellfish, including other types of clams, are able to purge the toxin in a relatively short time, domoic acid is retained by razor clams, making them the target of beach closures when toxin levels are high.
"We haven't had a closure in nearly eight months and that was due to PST," says Manderson. "But these toxin levels can rise fairly quickly. That's why we watch so closely."
Staff from ODA and the Oregon Department of Fish and Wildlife (ODFW) situated along the coast, with help from a team of volunteers, collect shellfish and phytoplankton samples every other week at 25 different locations or weekly if it appears there is a trend of rising toxin levels. Meat samples are iced, labeled, and rushed from the coast to ODA's laboratory in Portland within 24 hours of collection. If the lab finds samples reaching or nearing what is known as the alert level, it quickly notifies the Food Safety Division. Because the program is collecting and testing samples while the public is also harvesting, time is of the essence.
"If we didn't monitor shellfish for these toxins, we would always be reacting to a problem that had already occurred," says Manderson. "We don't want to wait until somebody actually gets sick before closing the harvest of shellfish in an affected area of the coast. Because of the ongoing sampling and testing program, we can take action before anyone gets ill."
The program also uses a relatively low-tech method of sampling phytoplankton to determine what might be happening with toxin levels in the shellfish. Plankton nets are dragged through the water at four or more collection sites on the coast, gathering and concentrating the algae in the bottom of the net. Microscopic examination identifies whether the type of algae collected is the kind that produces PST or domoic acid. ODA and ODFW team up to provide this invaluable monitoring tool.
Levels of domoic acid above 20 parts per million are considered above the safe level and lead to shellfish harvest closures even though it actually takes levels up to four times that amount to cause illness in people who consume the affected shellfish. ODA and ODFW publicize the closures but also make sure signs are posted along the coast in areas that have been closed to shellfish harvesting. The Oregon State Police patrols these locations to make sure no one is harvesting. A recent audit of the patrol effort was conducted by the Food and Drug Administration. Oregon received high marks.
"FDA requires a good audit in order for us to maintain interstate shipment of shellfish," says ODA's Bybee. "They looked at records maintained by ODA and the State Police to make sure what is being done to safeguard the public is sufficient. According to FDA, Oregon's audit covering the past two years exceeds the quality of regulation found in most other shellfish-producing states."
Recreational shellfish harvesters need to be aware of the latest conditions and test results, even before they make a trip to the coast. Current information on closures is provided toll free by ODA's shellfish safety hotline at 1-800-448-2474. Shellfish safety information and current status is also provided on ODA's website.
"It's a good idea to always check and make sure the beaches and bays are open," says Bybee.
All in all, ODA's Shellfish Program provides a valuable service to Oregon's important commercial shellfish industry, not to mention its protection of recreational harvesters who flock to the coast during the summer and throughout the entire year.
For more information, contact Bruce Pokarney at (503) 986-4559.
Story of the Week pdf version
http://oregon.gov/ODA/docs/pdf/news/110601shellfish.pdf
Audio Story of the Week
http://oregon.gov/ODA/news/110601shellfish_audio.shtml
|
|
|
|
|
|
|
|
|
|