Mercury is a metal, a chemical element that is liquid at room temperature. It is found naturally in deposits all over the world and is used in several applications like thermometers, switches and other scientific equipment. Ingestion of mercury can cause mercury poisoning, and accidents with this type of equipment has caused mercury to be phased out from most mainstream use. Many foods contain mercury, so their consumption should be limited, especially during pregnancy. Mercury poisoning can cause brain development problems in infants and children, and it can affect the central nervous system.
Mercury in Fish
Mercury pollutants fall from the air into rivers, streams and oceans, and they get absorbed by most fish and shellfish. Some fish accumulate more mercury than others, due to their environment and what that particular fish eats. Large fish that that eat a high amount of smaller fish tend to accumulate more mercury, because the smaller fish also have mercury in them -- which gets absorbed by the larger fish. Older fish that have lived longer also tend to have higher amounts of mercury, because they have had more time to accumulate the toxin.
Fish to Avoid
According to the Environmental Protection Agency, pregnant women -- as well as women who plan to become pregnant -- and young children should avoid shark, orange roughy, bigeye tuna, ahi tuna, swordfish, king mackerel and tilefish, because these fish contain unsafe levels of mercury. The EPA says there are no safe levels of these types of fish because their mercury content levels are so high.
Fish to Restrict
Fish that are labeled "high mercury" and should be limited to three or fewer 6-oz. servings per month are: bluefish, grouper, Spanish grouper, Gulf grouper, Chilean sea bass, canned white albacore tuna and yellowfin tuna. "Lower mercury" fish that should be limited to six or fewer servings each month are: carp, Alaskan cod, White Pacific croaker, striped bass, black bass, halibut, lobster, mahi mahi, monkfish, skipjack tuna, sea trout, perch, sablefish, skate, canned light tuna and snapper.
HFCS
A 2009 study published in "Environmental Health Journal" reports that many products with high-fructose corn syrup are contaminated with mercury. Caustic soda is produced using mercury cells, which causes the caustic soda to become contaminated with mercury. This caustic soda is then used in high-fructose corn syrup production, which contaminates the HFCS. Given that most North American's diets of processed foods high in HFCS, the accumulation of mercury at high levels is possible. Avoid foods high with high-fructose corn syrup, or purchase products made from mercury-free HFCS when possible.
References
- American Pregnancy Association: Mercury Levels In Fish; March 2011
- EPA: What You Need to Know About Mercury in Fish and Shellfish; 2004
- The Washington Post: Study Finds High-Fructose Corn Syrup Contains Mercury; January 2009
- "Environmental Health Journal"; Mercury from Chlor-Alkali Plants: Measured Concentrations in Food Product Sugar; Renee Dufault, et al; January 2009
