Shellfish Toxins

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Shellfish Toxins
Thuy D Do February 27, 2007
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Washington Shellfish Monitoring

• Began in 1947
• Generally biweekly April-October
• Determine toxin content of samples by bioassay
• Limits for closing much lower than tolerance
  level of humans
• Media notice and closure signs on some beaches

http//www.tpchd.org/files/library/3f99dac18661fbb
a.pdf
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Red Tide Facts

• Red tides caused by phytoplanktons
• Plankton populations highest in warm waters
• Most red tides caused by dinoflagellates
• Very few red tides are toxic
• Many toxins exist during normal tides
• Concentration in bivalves
• Plankton cysts settled at the bottom

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Shellfish

• Filter feeders
• A large oyster can filter up to 30L/hr
• Mussels accumulate toxins fast, used as an
  indicator species
• Butter clams can store toxins over 1yr after the
  exposure
• Cooking does not inactivate toxins

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Paralytic Shellfish Poison

• aka Saxitoxin
• Secreted by Dinoflagellates-Alexandrium catenella
• Found in mussels, clams, crabs, oysters,
  scallops,
• Herring, sardines, marine mammals, and birds
• Highest toxicity in July-August
• FDA limit .8ppm

http//www.bigelow.org/hab/toxin.htmldino
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Paralytic Shellfish Poisoning

• Symptoms
• Tingling of lips and tongue
• Tingling of toes and fingers
• Loss of control of limbs
• Difficulty breathing
• Death within hours
• 15 reported cases of PSP are fatal
• No known cure

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Diarrhetic Shellfish Poisoning

• Dinoflagellate bloom
• Okadaic acids, pectenotoxins, yessotoxins,
• dinophysistoxin
• Found in mussels, oysters, and scallops
• FDA limit .2ppm

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Diarrhetic Shellfish Poisoning

• Inhibits phosphatase 1 and 2a
• nausea, vomiting, abdominal pain, diarrhea
• Long term exposure ? tumors of the GI tract

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Amnesic Shellfish Poisoning

• Domoic acid from diatomes
• Razor clams, dungeness crabs, scallops, mussels,
  anchovies, sea lions, brown pelicans, and
  cormorants
• FDA limit 20ppm

http//www.bigelow.org/hab/cause.htmldia
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Amnesic Shellfish Poisoning

• Overstimulates the hypocampal neurons
• Also keeps Ca channels open in nerves and
  muscles
• Symptoms
• Vomiting
• Abdominal cramps
• Diarrhea
• Short-term memory

http//www.wdfw.wa.gov/fish/shelfish/razorclm/razo
rclm.htm
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Other Harmful Shellfish

• Toxins directly harmless to humans, but are
  disastrous to environment
• Vibriosis in Shellfish
• V. parahaemolyticus
• From consuming undercooked fish/shellfish
• 2-3 days food poisoning

http//www.doh.wa.gov/ehp/sf/BiotoxinProgram.htm