It’s a dilemma. Nutritionists say we should be eating more fish, especially sea-going oily fish. But many fish species are nearly fished out of existence. We’re supposed to be getting more lean protein, like that in seafood. But polluted oceans have given us a new danger — mercury poisoning.
Remember when actor Jeremy Piven was hospitalized for mercury poisoning? He pointed to his high consumption of sushi as the culprit. That shined a spotlight on the issue of mercury in fish.
Now, a consumer advocacy group in California has found higher amounts of this metal in supermarket fish than allowed by federal regulations. The group, Got Mercury?, tested swordfish, ahi tuna, yellowfin tuna and salmon from more than 40 stores around the state. According to Good Magazine, the results were not good.
“Their findings include the startling fact that more than a third of the grocery store fish studied had levels of methylmercury in excess of the the FDA do-not-sell limit of 1 part per million, with swordfish being by far the worst offender. In fact, only 6 of the 32 swordfish samples analyzed came in below 1 part per million, and one fish, purchased at a Ralph’s in Los Angeles, had 3 parts per million.”
What does that mean? Mercury is a naturally occurring element. But it can cause mental illness and other serious diseases, even death, if the amounts in our bodies get too high. The Food and Drug Administration and other agencies have long recommended that pregnant women and young children avoid eating those kinds of fish known to have high mercury content, like swordfish and bluefin tuna.
How did it get there? Years of burning coal has resulted in mercury finding its way into our food supply. Mercury was common in the swamps of prehistoric Earth. It settled into the mud and was covered up by dying plants. Over millions of years, that plant and mud gunk became coal. When coal is burned, the mercury is released into the air as vapor. It attaches to water droplets in clouds and becomes part of the rain. The water then runs off into streams, rivers and eventually into the oceans where it gets into the plants and animals that live there.
What’s the danger? Mercury poisoning usually is cumulative, meaning it builds up over time. There’s some mercury in the air, but it’s the type that our bodies can deal with. Methylmercury does not break down and can become lodged in the muscles and fat tissue of our bodies. The smallest marine animals filter nutrients out of the sea water, so they pick up the diluted mercury. As small fish eat those and then are eaten by larger fish, the concentration of mercury increases. The highest, most dangerous amounts are in those fish that grow large and live for more than five years. Those include swordfish and the largest of the tunas, bluefin. Mercury can be found in smaller fish like yellowfin tuna and salmon, but usually in amounts small enough that poisoning is unlikely unless you eat a lot of it. And by a lot of it, we mean a lot more than eating fish two or three times a week.
What can we do about it? First of all, both swordfish and bluefin tuna are endangered so you shouldn’t be eating them anyway. Stick to smaller tuna species for sushi. Also, smaller fish like sardines have high nutrient value, are more sustainable but are less likely to contain problem amounts of mercury. Cooking does help partially break down mercury, but doesn’t completely remove it. If you are pregnant, elderly, under 12 or have chronic health issues, limit or avoid exposure to raw fish and cooked versions of large fish. Also, we can demand better funding of those state and federal agencies responsible for regulating our food supply so they have the tools to locate and remove these problems before they get to our table.