A chemical that can accumulate in seafood and is known to cause brain damage is also toxic to the kidneys, but at much lower concentrations, according to a study appearing in an upcoming issue of the Journal of the American Society of Nephrology.The findings suggest that officials may need to reconsider what levels of the toxin are safe for human consumption.

The neurotoxin domoic acid, also called "Amnesic Shellfish Poisoning," is a very stable, heat resistant toxin that is becoming more prominent in coastal regions, likely due to environmental changes, according to background information in the study. It can accumulate in mussels, clams, scallops, and fish, and the FDA has set a legal limit of domoic acid in seafood based primarily on its adverse neurological effects.

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Domoic acid's affect on the kidneys
Because domoic acid is cleared from the body by the kidneys, P. Darwin Bell, PhD, Jason Funk, PhD, from the Medical University of South Carolina, and their colleagues looked to see if the toxin might also have detrimental effects on these organs. By giving mice varying doses of domoic acid and then assessing animals' kidney health, the team found that the kidney is much more sensitive to this toxin than the brain.

"We have found that domoic acid damages kidneys at concentrations that are 100 times lower than what causes neurological effects," said Dr. Bell. "This means that humans who consume seafood may be at an increased risk of kidney damage possibly leading to kidney failure and dialysis."

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While the findings need to be verified in humans, the researchers said they would like to see increased awareness and monitoring of domoic acid levels in all seafood. They say that the FDA may also need to reconsider the legal limit of domoic acid in food due to its kidney toxicity.