New York Times
February 10, 2004


By Jennifer Lee

WASHINGTON, Feb. 9 -- More than one child in six born in the United
States could be at risk for developmental disorders because of mercury
exposure in the mother's womb, according to revised estimates released
last week by Environmental Protection Agency scientists.

The agency doubled its estimate, equivalent to 630,000 of the 4
million babies born each year, because recent research has shown that
mercury tends to concentrate in the blood in the umbilical cord of
pregnant women.

The Centers for Disease Control and Prevention estimates that one
woman in 12 of childbearing age has a mercury level in the blood that
poses a concern. But recent research has shown that the umbilical cord
can have an average mercury concentration 1.7 times as great as the
concentration in the mother's blood.

The senior mercury researcher at the E.P.A., Dr. Kathryn Mahaffey,
said a newborn could exceed the safety concentration level of 5.8
parts per billion in a mother whose mercury concentration was just 3.5
parts per billion. Exceeding the safety level does not necessarily
mean that a baby will have impaired development, because researchers
build in a cushion between a defined safety level and the level known
to show harm.

Moreover, the mercury level in umbilical cord blood does not
necessarily match the level in the fetus.

Researchers say the estimates, presented last month at the National
Forum on Contaminants in Fish in San Diego, could change as federal
scientists reassess risks. Nonetheless, the new estimates fuel a
continuing debate on the hazards of methylmercury, an organic mercury
compound that concentrates in large marine animals and humans.

The Food and Drug Administration and the E.P.A. issued a more
conservative advisory that cautioned pregnant women and young children
to limit fish and shellfish to two to three meals a week.

Mercury pollution has become a contentious environmental issue with
the Bush administration's proposal to create a market-based
trading-pollution system. Advocates have been pushing for stricter
limits on mercury emissions from power plants, which emit almost 50
tons of mercury annually. But the direct chemistry of how and whether
power plant emissions end up in human beings is still being cleared

"I think between these new calculations and research findings, it is
now abundantly clear for this government to get serious about mercury
polluters," Linda Greer, a scientist with the Natural Resources
Defense Council, said. "We just can't watch these numbers go up in the
bloodstream of American women."

Copyright 2004 The New York Times Company