A full 25 percent of adult New Yorkers have elevated blood mercury levels, presumably caused primarily by eating fish, according to New York City’s Health and Nutrition Examination Survey (NYC-HANES) -- the first-ever of its kind. Other city populations may have similarly elevated levels, or higher ones, but have yet to document them.

Across the board, those with higher mercury levels were also those who ate more fish, including Asian people and higher-income New Yorkers. Further, the survey found:

• One-quarter of New York City (NYC) women aged 20-49 years have a blood mercury level at or above 5 µg/L (micrograms per liter), the New York State reportable level.

• The average mercury level among NYC women in this age group is three times higher (2.64 µg/L) than the national average for this group (0.83 µg/L).

• Those who eat fish four or more times a week averaged mercury levels in excess of the reportable level.
  

• Higher-income New Yorkers have higher mercury levels on average (3.6 µg/L) than the lowest income group (2.4 µg/L).

• Close to half (45 percent) of NYC Asian women have mercury levels at or above the reportable level.
  

A Warning for Pregnant and Breastfeeding Women

Elevated mercury levels are of particular concern for pregnant and breastfeeding women, along with those who may become pregnant, because the heavy metal is dangerous to the developing fetus and small children.

Mercury is transferred through the mother’s bloodstream to the fetus, as well as to a newborn through breast milk. A mother’s elevated mercury levels can cause cognitive delays and learning problems in the newborn.
 
Health officials say fish is still a healthy food choice that poses little risk to adults, but because of mercury risks to fetuses and children the Health Department has released a list of fish-consumption guidelines for pregnant and breastfeeding women, and young children:

• Choose fish lower in mercury
• Don't eat fish that are high in mercury
• Eat fewer, or smaller, servings of fish
• Choose smaller fish
• Eat a variety of fish

Science Daily July 23, 2007

Mercury is a known neurotoxin that can damage infants’ brains, leading to problems with attention span, language, visual-spatial skills, memory and coordination.

It is pretty much a fact that the more fish you eat, the higher your levels of mercury will be, primarily because seafood is so effective at bioaccumulating mercury that coal-fired power plants and other pollution sources have released into the ocean. This bioaccumulation in fish can increase the concentration in their flesh many millions of times more than is present in the water.

Mercury is most dangerous to developing infants and unborn babies, but it is, contrary to what the above study’s researchers said, still a risk to adults as well. Adults who have elevated mercury levels have been found to score lower on tests for motor skills, memory and concentration, which is not surprising considering mercury destroys nerve tissue and affects the area of the brain that controls complex movements and balance.

Most everyone could benefit from strictly limiting their fish intake to seafood that you know has been lab-tested to be safe -- most all fish served in restaurants would NOT meet this standard. The only seafood that I feel confident in recommending is Vital Choice Alaskan Wild Red Salmon, which we have done extensive testing on to confirm its purity.

The NYC Health Department’s brochure has also identified high-mercury fish that should NOT be eaten, particularly by children, pregnant women, breastfeeding women, or women who plan to become pregnant. These include:

• Chilean sea bass
• Grouper, marlin and orange roughy
• King mackerel and tilefish
• Shark and swordfish
• Tuna steaks and sushi-grade tuna
  

Pregnant and breastfeeding women can get the benefits of eating fish without risking toxic mercury exposure by taking a high-quality omega-3 fat supplement like krill oil.

Finally, as you pay careful attention to avoiding diet-related sources of mercury, watch out for other hidden sources as well, namely thimerosal in flu shots and mercury in silver dental fillings.

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