Seafood: To Eat or not to Eat?

I have eaten only a few ounces of seafood in my life. I was a picky eater as a child, and then I became a vegetarian, so I have almost no experience with eating fish. Now that I am recently married and contemplating having children, I am puzzled by contradictory messages about the consumption of fish. This is another one of those unbelievably complicated issues at the intersection of science and politics. Just the kind of thing I enjoy!

By now, you've heard about mercury levels in fish. Most of the mercury comes from coal-burning power plants. It is emitted into the air and eventually comes to rest in bodies of water. In the 1990s, the EPA under the Clinton administration limited mercury emissions from all other industries. The EPA was set to regulate power plants as well, with new regulations that would have reduced mercury emissions by 90% by 2008. Bush administration appointees weakened the regulations in 2003, requiring only a 70% reduction by 2018.

Animals don't easily absorb mercury in its natural form. It becomes problematic when it gets into water, though. Microorganisms methylate it into methylmercury (in this reaction, a hydrogen gets replaced with a methyl group), which is easily absorbed into digestive tracts and stored in fat and muscle. Small fish and algae eat the microorganisms, and larger fish eat them. A bigger fish will eat several smaller fish, and build up a concentrated dose. Most humans eat lots of the bigger fish in a lifetime and build up an even more concentrated dose. There have been documented affects on the human nervous system frommethylmercury poisoning, with the greatest danger to developing fetuses and young children.

Mercury isn't the only toxin found in concentrated doses in fish. Among the other dangerous chemicals are dioxins, DDT (dichloro-diphenyl-drichloroethane) and PCBs (polychlorinated biphenyls). The latter two chemicals have been banned from use in the United States for over 30 years, but they remain in the environment and in the water.

In 1994, the FDA issued an advisory that pregnant and nursing women should limit their consumption of fish (revised 2001 & 2004). The current position of the FDA is that women who are pregnant, thinking of becoming pregnant, or breast feeding should eat no more than 12 ounces fish that are lower on the food chain per week. The full advisory can be seen on their website. These warnings initially led to a decline in fish sales. But since the late 1990s, omega-3 fatty acids (a.k.a.docosahexaenoic acid a.k.a. DHA) have been heavily touted as beneficial to brain health and development and the decline in sales has reversed.

If these claims are to be believed, I may be doing potential harm to myself and my future children by not eating fish. I may have a higher risk of heart disease and less intelligence and ability to concentrate. My children may have lower IQs and more behavioral problems. The FDA approved the health claims after an intensive lobbying effort by the fish industry.

Omega-3s have been in the news a lot recently because of a press conference held by an organization called the National Healthy Mothers, Healthy Babies Coalition on October 4th. This is a non-profit coalition that includes scientists, members of the American Academy of Pediatrics, the March of Dimes, the National Institute of Child Health and Human Development, and the Centers for Disease Control and Prevention. They stated that pregnant and breast-feeding women should eat at least 12 ounces of seafood per week to avoid low birth weight, low IQ scores, post-partum depression, and behavioral problems. The FDA is not a part of this coalition and has not altered its position.

The story got more interesting with an article in USA Today on October 12. This article states that many scientists involved with the coalition are 'distancing'themselves from the statement. The article goes on to say: The dietary recommendations were put together by the Coalition's Maternal Nutrition Group. The group's work was paid for in part by a $60,000 grant from the National Fisheries Institute, a fishing industry trade association...

On Tuesday, the March of Dimes issued a statement saying, "We continue to recommend that pregnant and nursing women eat no more than a maximum each week of 12 ounces of fish that are low in mercury."

The National Institute of Child Health and Human Development, the Centers for Disease Control and Prevention, and the Health Resources and Services Administration issued a statement that they did not help craft the recommendation and learned about it only after it was announced.

The American College of Obstetricians and Gynecologists, one of the coalition's founding members, also said it supports the FDA's guidelines.

The National Healthy Mothers, Healthy Babies Coalition has posted a note on its website saying that the recommendation supported by its board "in no way implies that it has been endorsed by our member organizations."

"Clearly, when these studies come out that are funded by industry that completely dismiss the potentially harmful effects of mercury on mothers and fetus, one certainly has to question the validity of their findings," says Urvashi Rangan, a scientist at the Consumers Union, which publishes Consumer Reports.

So are omega-3s as important as they say? Are vegetarians' children less intelligent than those of the fish-eating population? I have personally known 3 people with vegetarian mothers who were vegetarian from birth who were also quite intelligent. A recent study published in the British Medical Journal and summarized on the BBC website found that vegetarians were generally more intelligent than the general population. The Vegetarian and Vegan Foundation also refutes the fact that eating fish is better for heart health or intelligence than eating fruits and vegetables.

I'm inclined to believe that much of the hype about omega-3s comes from an industry worried about losing consumers due to toxic chemicals in their product. In order to preserve their profits, they ought to be active in trying to promote regulation of the polluters. Think about it, fishing industry, think about the difference you could make in all of our lives and the good press you'd get if you assumed this strategy. We know you have powerful lobbyists at your disposal.

Contaminants aren't the only concern of the fishing industry, though. Fish populations around the world are in rapid decline. Humans have become too good at catching fish and are catching more than can be replenished through reproduction. We are also damaging habitats with global warming, trawling, and pollution. It is hard to count the number of fish in the ocean, but a very thorough study was published in the journal Nature and summarized here in 2003. The authors found a 90% reduction in worldwide fish populations since 1950. The only way to prevent a complete collapse of every large species is through a 60% reduction in fishing worldwide. Since the world's governments have not come together to commit to saving the oceans, it's up to each consumer to reduce their individual consumption by 60%.

For the remaining 40%, there are several websites that provide downloadable pocket guides that you can take along to the store or restaurant to ensure that you are making the best possible selection in terms of health and sustainability:
The Monterey Bay Aquarium
Environmental Defense
The Blue Ocean Institute

As a footnote, I know that some readers will wonder about whether farmed fish are the solution. Greenpeace describes the problems with fish farming on their website:

Aquaculture is often promoted as being the solution to sustainable fisheries, and has undergone a massive growth over the last 50 years. Unfortunately, with the exception of some shellfish farms and freshwater fish reared in ponds, most aquaculture exacerbates the pressures placed on over-exploited marine ecosystems. In particular:

* Wild caught fish are used for fishmeal and fish oil to feed farmed stocks. It takes over three tonnes of wild fish to produce one tonne of salmon.
* Industrial fishing for smaller fish like sandeels and anchovies for use in fishmeal has caused massive disruption to marine food webs. It has almost certainly led to the decline in numbers of cod, seals and seabirds in the North Sea.
* Disease spreads easily from farmed to wild populations, further depleting wild stocks.
* Water and surrounding ecosystems are polluted by chemicals, antibiotics and vaccines used to control diseases in intensively farmed fish.
* Many aquaculture practices are associated with poor human rights records, including loss of land and access to fishing grounds and poor employee rights.

I will also add that farmed fish are much higher in fat since they are penned in for their entire lives.