Mercury in fish: scientists study Asians for health risks

Asians, who eat more fish than other ethnic groups in the U.S., have significantly higher levels of mercury.

While fish is a good source of protein and beneficial omega 3 fatty acids, eating a lot of fish high in mercury can increase the risk for cardiovascular disease in adults and affect the neurocognitive development of children whose mothers consume the fish while pregnant.

Asians eat more fish than any other ethnic group in the United States, and studies have found that Asians living in New York and Seattle have significantly elevated levels of mercury compared to non-Asians, based on hair and blood analysis.

With a five-year, $2.6 million grant from the National Institute of Environmental Health Sciences, UIC School of Public Health researchers will measure levels of mercury and estimate levels of PCBs — another pollutant known to concentrate in fish — in Asians living in Chicago.

“We believe that Asians in Chicago, similar to Asians in other cities, are at a higher risk of having elevated mercury levels compared to other populations,” said Susan Buchanan, clinical associate professor of environmental and occupational health sciences.

“We want to know if there are specific, ethnic, fish-consumption practices or preparations that contribute to the mercury burden in this population.”

The findings will help them develop targeted text messages to Asians with the highest risk of mercury- or PCB-related heath problems. The texts will include information on safe fish consumption and general health.

Previous studies found elevated mercury in a third of Asians living in Seattle and 46 percent of Asians in New York City. The National Health and Nutrition Examination Survey found 28 percent of Asians over 50 had elevated mercury, compared to 5 percent of others in that age group.

Risks of fish sauce, fishhead soup

Buchanan and co-principal investigator Mary Turyk, associate professor of epidemiology, learned that new mothers of Chinese descent are encouraged to eat fishhead soup to promote milk production.

“Right now, we don’t know if eating fishhead soup or other ethnic fish preparations are a significant risk factor for elevated mercury levels,” Turyk said.

“So we’re very interested in getting a better idea of how fish sauce and other fish preparations impact mercury levels, so that we can tailor our interventions to best reduce risk.”

Buchanan and Turyk will partner with Asian community organizations in Chicago to recruit adults of Chinese, Korean and Vietnamese background to participate in focus groups, complete surveys and provide hair samples for analysis, both before and after the text-messages.

Because PCB levels are difficult and costly to determine in the body, the researchers will estimate exposure by measuring PCBs in fish purchased at stores where the participants shop.

Risk profiles for the various Asian ethnic groups will be used to craft and target the text-message intervention.

“It’s very important to balance the risk and health messages associated with eating fish,” Buchanan said. “If we can narrow down the risk messaging to those subpopulations that are most at risk, we can help people consume fish safely.”

The Midwest Asian Health Association is a participant in the grant.