Mercury

In 2003, the Centers for Disease Control reported that 1 in 12 U.S. women of childbearing age have unsafe levels of mercury in their bodies.  How bad it it?  Forty-four states and territories have issued health advisories about eating fish caught in local waters, and new research is raising red flags about mercury in canned tuna, a staple of kid’s lunchboxes across the country.

Reference:  Dr. Roger Schlickeisen, President Defenders of Wildlife, Summer 2004 issue, p. 5

Mercury Contamination in Fish

As of 2004, it is illegal for women in Greenland to breastfeed their children due to high levels of chemical contaminants that accumulate from their primary diet of fish.  This is attributed to the jet-stream winds from America that are deposited into the Ocean around Greenland.
            From:    - Los Angeles Times, Jan. 13, 2004, p. A1

Following are excerpts from:  Science and Health, The Mercury Story, Jan 21, 2005
Published by Public Broadcasting System: http//www.pbs.org/now/science/mercuryinfish.html

In America one-in-six children born every year have been exposed to mercury levels so high that they are potentially at risk for learning disabilities and motor skill impairment and short-term memory loss. That type of mercury exposure is caused by eating certain kinds of fish, which contain high levels of the toxin from both natural and man-made sources such as emissions from coal-fired power plants.

One government analysis shows that 630,000 children each year are exposed to potentially unsafe mercury levels in the womb. If the government and its scientists know about the mercury problem, why do so many people continue to be poisoned?

Over recent years NOW has examined how the influence of the tuna industry on the FDA may be putting Americans and their children at risk for mercury poisoning. Tuna, widely known for its health benefits, is one of the most popular foods on grocery store shelves. And, in 2000, FDA draft advisories presented to focus groups warned women not to eat a lot of canned tuna during pregnancy because it contains levels of mercury that can harm developing fetuses and nursing babies. In March 2004, the FDA and the EPA issued the first ever joint advisory on this topic, What You Need to Know About Mercury in Fish and Shellfish .

Nearly all fish contain trace amounts of methylmercury. How does this element get into our fish supply? Mercury occurs both naturally and from man-made sources. Some of it can be traced to coal-burning power plants. Smokestacks release toxic mercury emissions which rain down into rivers, lakes, and oceans. Bacteria convert the mercury to a form that's easily absorbed by insects and other small organisms. Mercury moves up the food chain as small fish eat the small organisms and big fish eat the smaller fish. The highest concentrations accumulate in large predators such as shark, swordfish and tuna...some of America's favorite fish.

Pregnant women, nursing mothers, and very young children are cautioned against excessive consumption of these fish.

Step 1  - DETERMINE EPA's RECOMMENDED LEVEL FOR A 45 LB CHILD

Multiply child's body weight by EPA's reference dose.

Convert 45 pounds to kilograms = 20.45 kilograms

20.45 kilograms x .1 micrograms per kilogram per day

EPA RECOMMENDED LEVEL = 2.05 micrograms per day = 14.35 micrograms per week.

Step 2 - HOW MUCH MERCURY IS IN 6 OUNCES OF CHUNK WHITE TUNA?

Multiply amount of fish by average mercury level for chunk white albacore.

Convert 6 ounces to grams = 170 grams 170 grams X .31 ppm  (or micrograms per gram)

MERCURY INGESTED = 52.7 micrograms per gram  

Step 3 – COMPARE MERCURY INGESTED WITH EPA'S RECOMMENDED LEVEL

Divide 52.7 micrograms by 14.35 micrograms = 3.7

BY EATING 6 OUNCES OF CHUNK WHITE TUNA A WEEK, THE CHILD IS INGESTING ALMOST FOUR TIMES EPA'S RECOMMENDED DOSE.

In December 2003, the FDA began circulating a draft advisory warning women who are pregnant, nursing, or who might become pregnant about the dangers of mercury in seafood. Critics like the Environmental Working Group objected to the advisory's vague guidance on tuna, and subsequently filed a legal challenge, charging that the advisory did not meet standards for accurate government science established by the Data Quality Act.  In February 2004, a new analysis by the Environmental Protection Agency revealed that "about 630,000 children are born each year at risk for lowered intelligence and learning problems caused by exposure to high levels of mercury in the womb," nearly double the previous EPA estimate.

            From: http//www.pbs.org/now/science/mercuryinfish.html

Is Our Tuna Family-Safe?

Given its popularity, canned tuna is the largest dietary source of mercury exposure in the United States.  The government based their most recent guidelines on tests of mostly American brands of tuna, even though a growing proportion of the canned tuna consumed today in the United States is imported. In 2004, for example, 51 percent of the total U.S. supply of canned tuna came from foreign sources. Defenders conducted this study to determine whether all canned light and albacore tuna is similar in mercury content, as the current federal guidelines suggest.

Disturbing Results

Our testing results revealed high levels of mercury in canned tuna, including light tuna, which the FDA has categorized as a “low-mercury fish.” A significant proportion of light tuna we sampled contained levels of mercury high enough to pose a potential public health risk, particularly to children and developing fetuses. More than one-third (35 percent) of all cans in our sample had mercury levels above 0.3 parts per million  (ppm). Eating just one six-ounce can of this tuna a week would cause a 140 pound woman—and nearly all children— to exceed the EPA’s “reference dose” for mercury. In fact, based on this study, a 45-pound child eating one can of light tuna in a week would be consuming mercury at a level three times higher than the EPA’s recommended maximum allowable dose of mercury.

From:  The Mercury Policy Project Report issued by: 
DEFENDERS OF WILDLIFE,  www.defenders.org;

THE CENTER FOR SCIENCE IN THE PUBLIC INTEREST,  www.cspinet.org

MERCURY POLICY PROJECT,  www.mercurypolicy.org