April 11, 2022 — Eating fish is the most common way people are exposed to mercury — more specifically, methylmercury, a highly toxic organic compound. While low levels of exposure are typically harmless, and fish is a healthy source of protein, its overconsumption can lead to neurological problems, especially for fetuses and young children.
The amount of mercury in the atmosphere has quadrupled since the Industrial Revolution, according to some estimates. The pollution has been largely caused by emissions from coal-fired power plants, but other industries also play a role.
Though mercury levels in water are declining — thanks to decreasing coal use in North America and Europe, and technology that reduces sulfur in smoke stacks — scientists are now discovering that climate change might increase methylmercury levels in fish. That’s because fish are becoming more active with rising ocean temperatures, requiring more food and therefore, ingesting more mercury, according to a 2019 Harvard University study.
Researchers in Delaware and New Jersey are trying to find out where and why mercury levels persist. The research, they say, is part of an effort to manage marine fisheries and inform human health guidelines.
“Understanding how methylmercury accumulates in marine fish will help us identify and control its sources to the ocean, and studying how concentrations of methylmercury vary among fish that people eat will improve guidelines for safe seafood consumption,” said Dr. John Reinfelder, an environmental sciences professor at Rutgers University, who has been studying mercury levels in bluefin tuna populations.