Depending on the levels of exposure, high levels of methyl mercury can be toxic to the nervous system. The first signs of methyl mercury poisoning are numbness and tingling sensations around the lips, fingers and toes. Severe cases may include tremors or jerks. Most cases of this type of poisoning have occurred in countries where fish is consumed on a daily basis. If you think you may have symptoms of mercury poisoning have your physician test your mercury levels.
Methyl mercury amounts in fish and shellfish are measured in parts per million (ppm). Only a few species of fish reach the FDA limit for human consumption of 1 ppm. The average concentration of methyl mercury for commercially imported species is less than 0.3 ppm. For most people, the risk from mercury poisoning from eating fish is not a health concern yet. However, some fish and shellfish contain higher levels of mercury that may harm an unborn baby or a young child’s developing nervous system. The Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) advise women who may become pregnant, pregnant women, nursing mothers and young children to avoid some types of fish and eat fish and shellfish that are lower in mercury.
By following these recommendations, women and young children can receive the benefits of eating fish and shellfish with reduced exposure to the harmful effects of mercury:
1. Do not eat Tilefish, Swordfish, King Mackerel, and Shark due to their high levels of mercury.
2. Eat up to 12 ounces a week of a variety of fish and shellfish that are lower in mercury such as shrimp, canned light tuna, salmon, Pollock and catfish. Note that albacore “white” tuna has more mercury than canned light tuna.
3. Check local advisories about levels of mercury found in fish caught by family and friends in local areas. If no advice is available, eat up to 6 ounces (one average meal) of fish per week to be safe.
The bottom line for the general population is to minimize your intake of Shark, Swordfish, King Mackerel, and Tilefish to once a month. Limit all other fish to 12 oz (2 average meals) per week, and call local fish advisories if needed. Overall, understand that no food is risk free. Enjoying fish in moderation has many health benefits and should be included in safe amounts in your diet.
For further information about the risks of mercury in fish and shellfish call the U.S. Food and Drug Administration information line at 1-888-SAFEFOOD or visit their website
www.cfsan.fda.gov/seafood1.html .
For more information regarding locally caught fish and shellfish, visit the Environmental Protection Agency’s Fish Advisories website
www.epa.gov/ost/fish or contact your local Health Department.
References
Robb, Matthew, Today’s Dietitian, Nov 2004 “Seafood Safety Is Something Fishy Going On?” p 29-31.
Article by Cristie Lynn Utter MS, RD, LD
