About the Biotoxins and Illness Prevention Program

Program Goals

The goal of the Biotoxin Program is to protect humans from illness and death caused by eating shellfish contaminated with biotoxins. The program encompases both commercially and recreationally harvested molluscan shellfish (those that have a hinged shell such as clams, mussels, oysters, geoduck, and scallops).

Biotoxins are poisons that are produced by certain kinds of microscopic algae (a type of phytoplankton) that are naturally present in marine waters, normally in amounts too small to be harmful. However, a combination of warm temperatures, sunlight, and nutrient-rich waters can cause rapid plankton reproduction, or "blooms." These blooms are commonly referred to as harmful algal blooms or "HABs" because of their potential to cause illness.

Biotoxin Monitoring

Shellfish in both recreational and commercial harvest areas are routinely tested for biotoxins known to be present in Washington marine waters, such as Paralytic Shellfish Poison, Amnesic Shellfish Poison, and Diarrhetic Shellfish Poison. When toxins are detected at dangerous levels, we close the harvest area. We continue to test the closed area, and when lab results confirm that biotoxin concentrations have dropped again to safe levels, we reopen the area to harvest.

When we close an area that is on or near a public beach, we notify the local health department and issue a news release about the closure. We also post the closure information on our website and include it in our recorded hotline to let recreational harvesters know that shellfish in that area are not safe to eat. Danger, Warning, or Closure Signs (PDF) are placed on the beach, but they are often vandalized or stolen. Beachgoers should not count on warning signs to let them know if a beach is closed for harvest.

When the closure is in an area that is commercially harvested, we contact all licensed companies harvesting in that area and notify them to stop harvesting immediately. We also recall any commercial product on the market that came from the closed area.

Biotoxin Testing is Done in a Lab

All Washington shellfish testing is currently performed at our Public Health Laboratory in Shorline. At this time there is no certified reliable biotoxin test that can be performed outside of a laboratory environment.

Biotoxin Levels are Unpredictable

They can rise quickly and remain high for long periods of time, and they can drop just as quickly to safe levels. There are no reliable indicators at this time to suggest when biotoxin levels will increase or decrease, although research is being conducted in this area. Prediction prototypes are currently underway for several regions in the U.S., including Washington State. The National Oceanic and Atmospheric Administration is actively involved in this research.

Illness Investigations

Activities included in the Biotoxin Program are those that focus on shellfish-related illnesses. Washington State has an international reputation for providing safe shellfish; however, illness outbreaks occasionally do occur. The program works closely with local, Tribal, state, and federal health officials to investigate shellfish related illnesses and to take necessary prevention steps, such as closing growing areas and recalling product. For more information see our pages on Norovirus and Vibriosis.


Marine Biotoxins

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