New Evidence: Low Level Mercury in Fish a Health Hazard

"The problem is that we are not given enough information about just how much mercury is in the fish that is widely available in stores and restaurants. Most American consumers are simply unaware that the fish they eat could be making them sick," she said.

The San Francisco doctor was the first to recognize low-level mercury poisoning in patients who regularly consume certain types of fish when she saw the symptoms some of her own patients had in common.

Dr. Hightower's research now extends from the individual patients in her practice to widespread mercury poisonings in Japan, Canada, and Iraq.

She says the FDA guidelines for mercury "are rooted in a study of the victims of a mass methylmercury poisoning in Saddam Hussein's Iraq." But the poisoned food in that study was not fish - it was wheat.

"An associate in Iraq's health ministry who oversaw the study of Iraqi victims of mercury toxicity has recently revealed that he withheld information from researchers - information that might have shown severe effects at much lower levels of exposure," she warns.

An article on the Corrosion Doctors website gives some idea of the numbers of people affected by that methylmercury poisoning in food.

"In the early 1970's a major methyl mercury poisoning catastrophe occurred in which an estimated 10,000 people died and 100,000 were severely and permanently brain damaged. Saddam Hussein's regime was largely successful in suppressing information about the event," the site states.

In the late 1960's and early 1970's, Iraqi harvests failed to produce enought to feed the people.

Officials decided to import a newly branded "wonder wheat" from Mexico, but they worried that the seed might grow moldy during the long, humid ocean journey to Iraq if it was not dressed with some fungicide.

"Methyl mercury became the most cost-effective fungicide, because it had recently been banned in Scandinavia and several American states due to environmental and toxicological risks," Corrision Doctors explains. "So the world market was flooded and prices dropped."

Dr. Hightower says that when the FDA and the swordfishing giant Anderson Seafood Inc. went to court in the mid-1970s over the FDA's consumption guidelines, Anderson used the Iraqi study as proof that high levels of mercury exposure are safe for the general public.

Older, larger fish will be the ones with the highest concentration of mercury. (Photo by Daina S.)

But Dr. Hightower says she learned that one of the lead investigators of the Iraqi poisoning disputed the fishing industry's claim of how much mercury is safe to eat.

Government agencies around the world, including the U.S. Environmental Protection Agency, have moved away from the idea that there are "safe" levels of mercury blood levels based on the Iraq studies. But still Hightower says the FDA has failed to adequately warn the public that mercury-laden seafood is a major threat to their health.

The concern reaches far beyond women of childbearing age and children, she said Wednesday as her book, "Diagnosis: Mercury: Money, Politics, and Poison," was released.

"Common sense says that if you are not feeling well, and are eating poison, then stop eating it and see if you feel better," said Dr. Hightower.

"'Diagnosis: Mercury' brings together the strongest evidence to date that the FDA's guidelines for fish consumption are insufficient," said Chuck Savitt, president of Island Press, which published the book.

"We simply don't know how widespread low-level mercury toxicity is in the United States, and this book tells us that regular consumers of certain types of fish are in danger," Savitt said.

"Diagnosis: Mercury" makes a case for increased study and stronger FDA regulation of this poison in food supplies.

The current California Department of Health fact sheet on mercury in fish warns local fishermen, "Fish from some areas of California have mercury or other chemicals in them."

"Most fish that you buy in stores or restaurants are safe. But even these fish may contain mercury," warns the state agency, naming the dangerous fish as "shark, swordfish, tilefish or king mackerel."

The state advises that fish with little or no mercury are store-bought farmed catfish, tilapia, wild salmon, pollock, shrimp, and scallops.

Health officials generally recognize that older, larger fish, higher on the predatory food chain will be the ones with the highest concentration of mercury in their meat.

The Hawaii State Health Department advises that fish small enough to fit in a pan are the ones that will have the least mercury.