On Monday, the Washington Toxics Coaltion sent out this Tweet:

RT @SeattleMamaDoc: "There is really no place 4 mercury in children." Ped neuro Dr. Suresh Kotagal 2 FDA panel re:mercury fillings @Mtnmd

The issue is whether mercury fillings for teeth should be banned due to concerns about that metal. I am not familiar with the science on mercury fillings, but the Tweet gave me a sense of deja vu, particularly appropriate for Groundhog Day.

A lack of familiarity with the science hasn't prevented the Toxics Coalition and others in the environmental community from passing along numerous scares regarding mercury – scares that ended up harming the people they claim to be concerned about.

Two stand out.

Eating Fish During Pregnancy

The Washington Toxics Coalition says simply, "Women and children should not eat tilefish or tuna steaks, and should limit their consumption of canned tuna."

The British medical journal, The Lancet, debunked this scare years ago, finding, "Children born to mothers-to-be who ate an average of 12 meals of fish a week – about 10 times the average U.S. citizen eats – showed no harmful symptoms." The women studied had six times the levels of mercury as average U.S. women, but found no negative impacts.

Another study found that eating more fish, including tuna, is good for pregnant women, noting that it is the best way to receive some important nutrients. A group of obstetricians and doctors of nutrition in coordination with the National Healthy Mothers, Healthy Babies Coalition released their recommendations in 2007, saying:

...women who want to become pregnant, are pregnant or are breastfeeding should eat a minimum of 12 ounces per week of fish like salmon, tuna, sardines and mackerel, and can do so safely. The Group found that eating fish is the optimal way to gain the benefits of long-chain omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Seafood is the richest dietary source of DHA and EPA in Americans' diets. The Group also recognized that selenium, an essential mineral found in certain ocean fish, accumulates and appears to protect against the toxicity from trace amounts of mercury.

Last year the WPC highlighted research that specifically notes eating tuna is good for women, helping prevent endometriosis which can cause infertility. Reuters reported "Women who eat lots of tuna, salmon and other foods rich in essential omega-3 oils might be less likely to develop endometriosis than those whose diets are loaded with trans fats, U.S. researchers said."

The article goes on to list tuna as one of the best sources of omega-3 oils, saying:

Most of the omega-3 fatty acids eaten by the nurses came from full-fat salad dressing, followed by fatty fish like tuna, salmon and mackerel. Walnuts and flaxseeds are also considered good sources. Omega-3 fatty acids, considered essential for good health, can lower heart disease risk.

So, in addition to reducing the risk of endometriosis, tuna is a great source of omega-3 oils that lower heart disease risk. Studies continue to reveal that mercruy levels in seafood are an exaggerated risk, with the benefits of eating fish, including tuna, far outweighing the risks.

When will the Washington Toxics Coalition correct its recommendations and quit giving pregnant women bad health advice?

Vaccines

Environmental activists have been among those pushing the claim that a vaccine preservative called Thimerosal, derived from mercury, caused autism. Previous research showed the link to be false noting:

Researchers from the state Department of Public Health found the autism rate in children rose continuously during the 12-year study period from 1995 to 2007. The preservative thimerosal has not been used in childhood vaccines since 2001…

The damage, however, had been done. Along with the claim that the MMR vaccine caused autism, the thimerosal scare pushed down vaccination rates leading to increased sickness among children and even some deaths.

These are real impacts, harming real people. In some cases groups like the Washington Toxics Coalition simply move on to the next scare. In other cases they continue to pass along bad information.

The problem is that their claims are so repetitive that people begin to believe them, making decisions that leave them and their children worse off. It's like a bad movie.