Study Finds Mercury Exposure Higher in Asians, Pacific Islanders and Native Americans

Until recently, Asian, Pacific Islander and American Indian Women in the United States had not been identified as a high-risk group for exposure to methylmercury through fish consumption.

Research/Academic Showcase

Dr. German T. Hernandez Dr. German T. Hernandez served as senior author of the study conducted with investigators from the University of California and the California Pacific Medical Center in San Francisco.

In February, German T. Hernandez, M.D., F.A.S.N., Assistant Professor of Medicine, Texas Tech University Health Sciences Center at El Paso, served as the senior author of a study published in Environmental Health Perspectives, the monthly journal of peer-reviewed research and news on the impact of the environment on human health published by the National Institute of Environmental Health Sciences. Dr. Hernandez completed the research at UC-SF prior to joining the Health Sciences Center team at El Paso.

The study found that among women of childbearing age who self-identified as Asian, Pacific Islander, or American Indian (or a race/ethnicity other than Hispanic, black or white) 16 percent had elevated levels of mercury in their blood as compared to only five percent of the Hispanic, black and white women who were in the study.

Dr. Hernandez, along with investigators from the University of California and the California Pacific Medical Center in San Francisco, say that although omega–3 fatty acids in fish have been associated with healthful benefits, there is increasing evidence that the mercury content in some fish, if consumed too frequently, may lead to adverse health effects.

Some of these effects may include cardiovascular disease, autoimmune disease, infertility, and neuropsychiatric effects. Many of these effects may occur at mercury levels previously thought to be safe, according to Hernandez and the co-authors.

The study looked at 3,637 women of child-bearing age because the greatest concern is mercury’s potential to cause permanent damage to the developing brain of the fetus.

Because Asian, American Indian, and Pacific Islander women have not been previously identified as a high-risk group for mercury exposure, the Hernandez and his fellow investigators recommend further studies focusing on these populations.

According to information provided by the Food and Drug Administration, mercury occurs naturally in the environment and can also be released into the air through industrial pollution. Mercury falls from the air and can accumulate in streams and oceans and is turned into methylmercury in the water.

Fish absorb the methylmercury as they feed in these waters. It builds up more in some types of fish and shellfish than others, depending on their lifespan and what the fish eat.

Swordfish is a particularly popular fish for cooking Swordfish is a popular fish for cooking. Larger fish like swordfish, shark, king mackerel and tilefish that have lived longer tend to have the highest levels of methylmercury.

Nearly all fish and shellfish contain traces of methylmercury. However, larger fish that have lived longer have the highest levels of methylmercury because they've had more time to accumulate it. These large fish (swordfish, shark, king mackerel and tilefish) pose the greatest risk. Fish considered to be safer to eat include sardines, canned light tuna and salmon. Other types of fish and shellfish may be eaten in the amounts recommended by the FDA and the Environmental Protection Agency.

People who regularly eat types of fish that are high in methylmercury can accumulate it in their bodies over time. Methylmercury is removed from the body naturally, but it may take longer than a year for the levels to drop significantly. This is the reason why women who are trying to become pregnant should also avoid eating certain types of fish.

 

- Lisa Ruley

 

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Jan 15, 2020