Scripps Howard News Service
February 28, 2005

By Joan Lowy

The diminished intelligence of children exposed to mercury
contamination before birth costs the U.S. economy $8.7 billion a year
in lost productivity, according to a study published Monday in a
government science journal.

The study estimates that between 317,000 and 637,000 of the 4 million
children born each year in the United States are exposed in the womb
to mercury levels above the Environmental Protection Agency's safety

The IQ loss to children whose mothers' blood level of mercury was at
or above EPA's safety level was subtle and varied depending on the
mother's exposure, according to the study in Environmental Health
Perspectives, a journal published by the National Institutes of
Health. The peer-reviewed study was done by pediatricians at the Mount
Sinai School of Medicine and the Albert Einstein College of Medicine,
both in New York.

Children with mothers whose mercury levels were at or near the safety
level suffer an IQ loss of less than 1 point, while children whose
mothers are among the 5 percent of the population most highly exposed
suffer IQ losses ranging from 1.6 points to 3.21 points, the study

"While this diminution in intelligence is small in comparison with the
loss of cognition that can result from other genetic and environmental
processes, the loss resulting from (mercury) exposure produces a
significant reduction in economic productivity over a lifetime," the
study said.

The estimate of $8.7 billion in annual economic impact from mercury
was calculated using methodology employed in previous studies of the
economic impact of lead exposure, which also lowers intelligence.

The health and societal impacts of mercury "are very analogous to
lead," said Dr. Philip Landrigan, a co-author of the study.

"When I started out in pediatrics we used to think of lead as an all-
or-none disease _ either you had convulsions or other gross symptoms
or no symptoms at all," Landrigan said. "Then in the '70s we realized
that not everybody was obviously sick, but they were still injured
through the loss of a few points of IQ, their attention span was not
as long as could be or they had behavioral problems."

Coal-fired power plants, the single largest source of man-made mercury
emissions in the United States, are responsible for $1.3 billion of
the economic loss, the study found.

Leonard Levin, mercury issue manager for the industry-funded Electric
Power Research Institute, said the study relies on limited or flawed
data in its calculation of the effect of mercury exposure on fetal

"There is a huge uncertainty around whether there is any effect or
not" on intelligence from low levels of mercury exposure, Levin said.
The study also overstates the number of children exposed and
exaggerates the contribution of power plants to mercury pollution,
Levin said.

Mercury emissions from power plants, incinerators, industrial
processes and natural phenomena like volcanoes settle in water bodies.
Microbes transform the deposits into methylmercury, the most toxic
form of mercury. The contaminant then works its way up the food chain.

People are exposed to mercury primarily by eating fish, especially
large, predatory species like shark, swordfish and some species of

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