Filed Under: Seafood

People’s Republic of Mercury: China, Part Two

The Ninth International Conference on Mercury as a Global Pollutant has been heating up the Chinese city of Guiyang this week, and we’re continuing to absorb the latest research. Needless fear of tiny mercury traces have threatened to change fish from a health food into the equivalent of industrial waste. Is the skull-and-crossbones approach to seafood safety justified? Or do all those omega-3 fatty acids, and other nutrients, still make fish a smart part of our diets? Yesterday the big draw in Guiyang was a series of presentations from scientists who are continuing to hedge their bets—but their findings clearly put fish back in the “good” column:

Researchers examining why the bodies of Japanese and Koreans seem to react differently to mercury had this bottom line for the audience: “It has become obvious to us that we also need to consider the benefits of fish when we’re trying to provide guidance to specific people.”
A study measuring the mercury levels of 20,000 visitors to Japan’s National Institute for Minamata Disease determined that 15 percent of childbearing-age women had more mercury in their systems than their government recommends. But the lead researcher’s PowerPoint  presentation ended with this bold statement: “Fish is a healthy food.”
Another Japanese team tried to sort out what happens when pregnant women get traces of mercury along with significant doses of omega-3 fatty acids in the same serving of fish. “Yes, fish contain methylmercury,” the presenter told us. “However, pregnant women should not stop eating fish.”
Scientists in Zhoushan (a Chinese city) investigated whether the mercury levels of pregnant women who ate ordinary amounts of fish had any impact on the development of their children. The bottom line? “Prenatal low level mercury exposure had no significant impacts on infants’ development in [the] Zhoushan cohort.”
An Italian research team reported the latest results from their ongoing study of children in northern Italy, following them from infancy through elementary school: “[N]o association was found between prenatal and postnatal mercury exposure and neurodevelopment performances of children at 6-9 years.”
Harvard professor Emily Oken, presenting her research that was published last year in the American Journal of Epidemiology, told the conference: “Dietary recommendations for pregnant women should incorporate the nutritional benefits as well as the risks of fish intake.”
University of British Columbia environmental scientist Dr. Laurie Chan, who co-chaired the session on seafood and health, was singing our song with his presentation. “It is important,” he said, “to communicate the risk to the public without scaring them to the point that they would stop eating fish altogether.”

The primary dissent from all this good news came from two members of a scientific team studying whalingmen and others in Denmark’s Faroe Islands. Their study is the largest to document what they say is evidence of health harms from mercury in fish—even though their research population also eats lots heavily contaminated whale meat and blubber. (Is this sort of diet a meaningful model for Americans? Nope.)
Anyway, those health harms are so minuscule that they’re impossible to document in individual people: They have to be teased out of the data after complex number-crunching. So the Faroe team is pushing a new approach to stay relevant. If you want to see how bad mercury really is for your brain and your heart, they told the conference yesterday, you need a statistical model that can cancel out the health benefits of fish consumption. Then it’s obvious!
It’s as though some scientist in a windowless lab got the idea that it’s even possible to eat fish without reaping all those benefits. (It’s not.)
The pièce de résistance came from Dr. J.J. Strain, an Ireland-based scientist who works with a team studying the impact of mercury on a heavy fish-eating population in the Seychelles Islands. His study, he said, has continually “failed to show any relationship” between mercury in pregnant women’s diet and the health of their children.
Strain, a nutritionist who’s more concerned with real-world human diets than computer models, made the most dramatic point of the day. “Factoring out” omega-3s and other healthy nutrients in fish, he said, ultimately leads to a paradox: The healthier fish is, the more toxic we can make it appear. All you need is the right computer.
He’s right. And isn’t that what’s been going on since the first environmentalist decided to use seafood as a weapon?
Tomorrow we’ll discuss the burning question of just how all that mercury got into our oceans in the first place. (Hint: Mother Nature can be cruel.) And in addition to these updates, you can follow our coverage of the Guiyang conference on Twitter.

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