Seafood Safety for Women

by Diane, M.P.H, M.S.

Fish is an excellent source of protein, omega-3 fatty acids, vitamin D, and other nutrients for people of all ages and an exceptionally good food for pregnant mothers and their developing babies. Research has shown that fish consumption may actually enhance development of the nervous system in the developing fetus, infant, and young child. However, contamination with toxic mercury, polychlorinated biphenyls (PCBs), and other environmental pollutants has cast a shadow over the nutritional benefits of fish.

Methylmercury is toxic to the fetal brain and nervous system, and many popular fish species are contaminated with it. The principal exposure route for the fetus is consumption of contaminated fish by the mother. Women who eat fish during pregnancy, even as little as a single serving of a highly contaminated fish, may expose their developing child to excessive levels of methylmercury. The toxic metal can cross the placenta to damage the rapidly developing nervous system, including the brain, of the fetus. The risk of learning deficits, developmental delays, neurological problems, future school problems and remedial special education, increase in children who have been exposed even to relatively low levels of methylmercury in the womb.

The accumulation of methylmercury, PCBs, endocrine disruptors,and other toxins in the food chain in general may also be contributing to the increasing incidence of attention deficit disorders (ADD, ADHD), hyperactivity, behavior and developmental problems, as well as autism.

What is the source of mercury in our seafood? Combustion in power plants of coal containing mercury is the major source of this environmental pollution. Mercury pollution from coal-fired power plants moves through the air, is deposited in water, and finds its way into fish, accumulating especially in fish that are higher up the food chain. Fish like tuna, sea bass, marlin, and halibut show some of the worst contamination, but dozens of species and thousands of water bodies have been seriously polluted.

The Environmental Protection Agency’s (EPA) safe exposure estimate for methylmercury was dropped twice in the past 16 years, as science identified adverse effects in children exposed in the womb at lower and lower doses. The current safe dose may drop even lower in the future (NAS 2000). No one knows how long a fetus can tolerate a dose of methylmercury above a “safe level” without observable adverse effects.

On January 12, 2001, government health officials issued warnings for women to limit fish consumption during pregnancy to avoid exposing their unborn children to unsafe levels of methylmercury.

The Food and Drug Administration (FDA), which regulates commercially sold fish, recommends that pregnant and nursing women and young children not eat any shark, swordfish, tilefish, or king mackerel, but then recommends 12 ounces per week of any other fish. The Environmental Protection Agency (EPA), which makes recommendations to states about safe mercury levels in sport fish, allows up to 8 ounces of any fish per week for pregnant women, with no limits on consumption of any individual fish caught recreationally.

While these restrictions are steps in the right direction, they need to be tightened significantly to adequately protect women and their unborn children from the toxic effects of methylmercury and other contaminants.

The lack of information for pregnant women regarding methylmercury risks and mercury levels in the fish they buy pose another serious problem. According to the Centers for Disease Control and Prevention (CDC), about 10 percent of all women of childbearing age have blood methylmercury levels above the dose that may put their fetus at risk for adverse neurological effects (CDC 2001). If these women were to increase their consumption of certain fish species in hopes of benefiting their babies during pregnancy, they could expose their fetuses to potentially hazardous levels of methylmercury.

The following list was recently published by the Environmental Working Group (EWG):


King mackerel
Tuna steaks
Canned tuna
Sea bass
Gulf Coast Oysters
White croaker
Largemouth bass


Mahi mahi
Blue mussel
Eastern oyster
Great Lakes salmon
Gulf Coast blue crab
Channel catfish (wild)
Lake whitefish


Blue crab (mid-Atlantic)
Fish Sticks
Flounder (summer)
Trout (farmed)
Salmon (wild Pacific)
Shrimp: Pink shrimp from Oregon, spot prawns from Canada *

* Shrimp fishing and farming practices have raised serious environmental concerns.

** Farmed catfish have low mercury levels but may contain PCBs in amounts of concern for pregnant women.

Data from the 1970s show high concentrations in the following species (No recent data available):

Orange Roughy
Lake Trout


  1. “Complete List of Seafood Eco-Ratings: Which fish are safe for you and the oceans?” Environmental Defense Fund (EDF), 257 Park Avenue South, New York, NY 10010. General Information: (800) 684-3322. Copyright © 2011 Environmental Defense Fund. All Rights Reserved. Posted: 10/03/08; Updated: 05/08/12. (Source:
  2. “Safe Seafood Selector.” Environmental Defense Fund (EDF). 05/02/12.(Source:
  3. “Seafood Selector: Fish choices that are good for you and the ocean.” Downloadable and printable Pocket Guide (PDF). Environmental Defense Fund (EDF). 06/2011. (Source:
  4. “Seafood Watch: National Sustainable Seafood Guide.” Monterey Bay Aquarium Foundation. January 2012. (Source:
  5. “What Women Should KnowAbout Mercury in Fish.” Environmental Working Group (EWG). Headquarters: 1436 U Street. NW, Suite 100. Washington, D.C. 20009.  (202) 667-6982. (California Office: 2201 Broadway, Suite 308, Oakland, CA. 94612; Midwest Office: 103 E. 6th Street, Suite 201, Ames, IA. 50010; Sacramento Office: 1107 9th Street, Suite 340, Sacramento, CA. 95814). Copyright 2007-2012.



{ 1 comment }

Andy Peters November 16, 2012 at 3:10 pm

Dear Mrs. Dianesays,

I just read the below article on yahoo about what fish is safe to eat and thought of you. I love your posts. I wish I could follow them, but there is not a link on you page that I could find for people to follow your page and receive e-mail updates when you post.

Hope all is well,

Andy P.

Comments on this entry are closed.

Previous post:

Next post: