Linda's Hot  Topics
Mercury in Fish and Shellfish |
|
Fish and shellfish are an important part of a healthy diet. Fish and shellfish contain high-quality protein and other essential nutrients, are low in saturated fat, and contain omega-3 fatty acids. A well-balanced diet should contain a variety of fish and shellfish. However, nearly all fish and shellfish contain traces of mercury.
What is Mercury?
- Mercury is a naturally occurring element in the environment and is also released into the air through industrial pollution.
- Mercury is a neurotoxin, which means that it can damage the brain and nervous system.
- Fish and shellfish are the main sources of mercury exposure for humans. This mercury is in the form of methylmercury.
- Methylmercury is not the same type of mercury found in some thermometers or in dental amalgam.
- It takes one year to eliminate mercury from your body.
Who sets the standards for level of acceptability?
Environmental "Watch Dogs" have differing levels of acceptability for mercury. The Food and Drug Administration (FDA) has the least restrictive limits to ingestion and considers 1 part per million to be acceptable. The Environmental Protection Agency (EPA) and National Academy of Sciences (NAS) are about 3-5 times more limiting. An environmental research organization based in Washington, D.C., called Environmental Working Group, is even more adamant about restricting potential mercury ingestion. Their recommendations say to keep fish to about one meal per month.
How does Methylmercury get into fish?
- Mercury that falls from the air, through industrial pollution, can accumulate in streams and oceans. Bacteria in the water cause chemical changes that transform mercury into methylmercury. Fish absorb the methylmercury as they feed in these waters.
- Methylmercury builds up more in some fish than others depending on what they eat, how long they live, and how high up the food chain they are.
- Larger fish that have lived longer have the highest levels of methylmercury because they have had more time to accumulate it. These large fish pose the greatest risk.
What are the risks from eating fish and shellfish?
According to the FDA and EPA, for most people, the risk from mercury by eating fish and shellfish is not a health concern. Yet, some fish and shellfish contain higher levels of mercury that may harm an unborn baby or young child's developing nervous system. For these reasons the FDA and EPA are advising women who are pregnant or may become pregnant, nursing mothers, and young children to avoid some types of fish and to eat fish and shellfish that are lower in mercury. In general, the risks from mercury in fish and shellfish depend on the amount of fish and shellfish eaten and the levels of mercury in each fish.
What about the risks from fish caught in Texas?
In 2004, 35% of the Nations's total lake acres (about 14 million acres), 24% of the Nation's total river miles (about 840,000 miles) and 100% of the Gulf Coast were under a National Fish and Wildlife Contamination Advisory. In Texas, we currently have 12% of our lake acres and 0.1% of our river miles under advisory for a total of 25 fish consumption advisories for specific waterbodies.
For any state in the US, it is recommended that you do not to eat any other fish in the same week that locally caught fish are consumed. Before eating locally caught fish, research your state's advisories on mercury and PCB levels in caught fish. For a list of fish consumption bans and advisories in Texas go to the Texas Parks and Wildlife site
Recommended Guidelines for Selecting and Eating Fish or Shellfish
#1 High Mercury Level: Never Eat
- Shark
- Swordfish
- King Mackerel
- Tilefish (also known as Golden Snapper or Golden Bass)
#2 Moderate Mercury Level: One meal (up to 6 ounces) per month or less
- White (albacore) Tuna and Tuna Steaks (large predatory fish)
- Red Snapper
- Orange Roughy
- Pollock
- Halibut
- American Lobster
- Marlin
- Moon Fish
- Saltwater Bass
- Wild Trout
- Bluefish
- Grouper
#3 Low Mercury Level: One meal (up to 6 ounces) per week
- Canned Light Tuna (made from smaller Skipjack and Yellowfin)
- Crab
- Mahi Mahi
- Haddock
- Whitefish
- Herring
- Spiny Lobster
#4 Lowest Mercury Level: Two meals per week (up to 12 ounces total)
- Shrimp
- Wild Alaskan Salmon
- Farm Raised Catfish
- Ousters
- Farm-Raised Rainbow Trout
- Flounder/sole
- Perch
- Tilapia
- Clams
- Scallops
- Crayfish
#5 Other Tips
- When selecting tuna, choose canned light tuna. White (albacore) tuna and tuna steaks have more mercury than canned light tuna. So limit white tuna and tuna steaks to 6 ounces (one average meal) per week.
- Farm raised salmon were found to have much higher levels of chemical flame retardants (called PBCEs), PCBs (carcinogenic chemicals once used as insulator in electric equipment), and Dioxins than wild salmon. It takes 6 years to rid the body of PCBs and one year to eliminate mercury. The difference between farmed and wild salmon seems to be due to their diet.
- Fish sticks and "fast-food" sandwiches are commonly made from fish that are low in mercury.
- Do not to eat any other fish in the same week that locally caught fish are consumed.
- Other informative links:
Article written November 2005
|
