Friday, April 07, 2006
Seafood & Mercury
I like seafood. But recently I've been hesitant to buy or eat seafood because of the health risks involved. I wasn't sure which kinds of fish or shellfish had the toxic mercury I heard were found in seafood. This is something I didn't worry about when I lived in San Francisco because I bought my seafood at Whole Foods Market. Now that I live in Manila I have to be more careful because there are no indicators to what the mercury level is, if any, in the seafood bought anywhere in the country. So I did a bit of research for my peace of mind and so I may make informed decisions.
Mercury is found in all sea creatures. So there isn't a single seafood found in any market in any part of the world that will be free of mercury contamination. That’s sad isn't it? The implications of this is no longer merely ones health but extends to the health of the planet in general. Mercury is found in the atmosphere, soil, seas and lakes. It enters water systems mainly through rain and surface water run-off. Much of the mercury acquired by sea life comes from toxic heavy metals in the air and water, along with sediment that reaches aquatic life. Mercury comes from multiple sources, the most pervasive of which is from acid rain caused by powerplant emissions and from gold mining operations. Mercury contamination affects us globally since mercury can be transported through the atmosphere over large distances.
Mercury contamination poses health risks to adults and especially children and the unborn fetus. In adults, symptoms of mercury toxicity are hair loss, upset stomach, difficulty concentrating; numbness, burning or tingling of the extremities (lips, fingers, toes); fatigue; weakness; irritability; shyness; loss of memory and coordination; tremors; and changes in hearing and blurred vision. Extremely high mercury levels can permanently damage an adult's brain and kidneys, or even lead to circulatory failure. In the unborn child, infants and children, high levels of mercury can harm the developing nervous system, kidneys, liver and cause neurological damage.
Some fish have higher levels of mercury than others. Predatory, large and long-lived fish such as shark, swordfish, tilefish, orange roughy, tuna, marlin and king mackerel have the highest levels of mercury and should be avoided altogether. The lowest levels of mercury are found in shrimp, sole, tilapia, clams, oysters, herring, hake, scallops, anchovies, squid, flounder and sardines. In general, the smaller the fish the lower the level of mercury.
The good news is that mercury is released from our bodies through perspiration. But, this isn’t enough if one eats contaminated seafood regularly. The only other way to eliminate mercury from our bodies is to stop eating fish. It will take 2 to 3 months for the toxin be expelled but this is only for mercury we consumed recently. Mercury that has lodged itself in tissue is much harder to remove from our system. I would suppose fasting and taking bentonite would remove mercury together with other toxins from our bodies. The other thing is that we should not altogether eliminate seafood from our diets because we need to consume foods with omega 3 oils, which our bodies don’t produce naturally. So the best thing to do is to eat fish that has very low levels of mercury and consume more foods, such as nuts and seeds, that are high in omega 3 oils.
BusinessWeek, “Time To Scale Back On Big Fish?”
by Carol Marie Cropper, Jan 19, 2004
University of Kentucky - College of Agriculture,
“Mercury in Fish: Advice for Consumers”,
Oceans Alive, “Mercury in Fish and Shellfish”,
Natural Resources Defense Council, “Mercury
Contamination in Fish”,