New Mercury Warning for Tuna

Why was the Mad Hatter in Alice in Wonderland mad as a hatter? Before the use of mercury was banned in the 1940s, hat makers used it in their craft which left many of them drooling, twitching, lurching, befuddled and mumbling. These days, you don’t have to be in the millinery business to be worried about mercury—it is has invaded our waters and consequently much of the fish we eat.

We’ve been hearing about mercury in fish for a while, but now a new round of testing conducted by Consumers Union has found mercury in each of the dozens of cans and pouches, prompting a more stringent warning on tuna consumption. The samples were purchased in the New York Metropolitan area and online.

There is no debate about the toxicity of mercury poisoning from fish. It is most threatening to prenatal development—thus pregnant women are advised to practice extreme caution when eating fish. Young children and women planning on becoming pregnant are always advised to watch their mercury as well.

Consumers Union is urging pregnant women to avoid eating tuna altogether and advising small children to limit consumption. “White” tuna generally contained more mercury than “light” tuna, but some light tuna contained enough that a woman of childbearing age eating less than a can a week would exceed federal recommendations for mercury consumption, the new Consumer Reports study says.

Children who weigh less than 20kg are urged to limit their weekly intake to 0 to 110gm of light tuna or 0 to 40gm of white tuna, depending on their weight. For children who weigh at least 20kg, the recommended limits are 110 to 350gm of light tuna or 40 to 110gm of white tuna, depending on their weight.

Mercury occurs naturally, but is also a product of industrial pollution. In this guise it falls from the air and settles in our waterways—there, it is turned into methyl mercury and absorbed by fish. As it goes, larger and older fish have a longer time to build up mercury than smaller and younger fish. Plus, large predatory fish at the top of food chain generally have higher levels of mercury. Although the FDA had determined safe levels of methyl mercury consumption for adults—I’d rather just avoid the risk of neurological damage altogether, thanks.