By now we’re all familiar with the warnings about mercury in fish and canned tuna fish – that deli counter staple – has been particularly targeted by these warnings because of how frequently most of us consume it. Now it seems we should be even more cautious when it comes to tuna fish as the canned variety has been found to have even more mercury than previously thought.
Consumer Reports recently tested 42 samples of tuna from cans and pouches and found that every sample contained mercury, in amounts ranging from 0.018 to 0.774 parts per million. While the FDA won’t issue a recall unless the mercury content reaches 1 ppm or more, the levels found in this test amount to more than we should consume. Just 2.5 oz of white tuna exceeds the EPA safety threshold while 5 oz of light tuna (which is generally lower in mercury than the albacore variety) would be over the limit. The levels of mercury found in white tuna were also higher than previous tests performed by the FDA in 2002-2004.
Mercury, which finds its way into our waterways from coal plants, volcanos, and other sources, accumulates in fish in the form of methylmercury. Large fish, like tuna, have higher levels of mercury because they live longer and also ingest smaller fish that contain mercury, allowing the heavy metal to build up. When we eat the fish, we ingest the mercury as well. The primary danger of overexposure to mercury is neurotoxicity. Fetuses, infants and children are most susceptible to the effects of mercury, and it’s consumption can lead to developmental delays including impaired cognition, motor skills, memory, language, attention and visual spatial skills.
This is not to say that we should eliminate fish from our diets altogether. Fish, after all, is an important part of a healthy diet, providing a great source of protein and heart-healthy, brain-boosting omega-3 fats. Although the following guidelines for fish consumption have been established with children and women of childbearing age in mind, everyone should make low-mercury choices when possible:
- Light tuna is usually lower in mercury than white tuna, and therefore a better choice.
- When it comes to canned tuna, young women and children should limit their intake.
- Children under 45 lbs should consume less than 4 oz of light tuna or 1.5 oz of white tuna per week.
- Pregnant and breast feeding women should eliminate tuna from their diets entirely.
- Avoid shark, swordfish, king mackerel, orange roughy, marlin, and tilefish
- Eat up to 12 oz (~2 servings) of low-mercury fish per week. Low-mercury fish include salmon, shrimp, catfish, pollock, anchovies, crab, haddock, sardines, oysters, tilapia, and trout
- Check with your local advisory about fish caught by family and friends in area waters