Related Press:
EPA Revises Risk Estimates
By Guy Gugliotta
Washington Post Staff Writer
Friday, February 6, 2004; Page A03
A new government analysis nearly doubled the estimate of the number of newborn
children at risk for health problems because of unsafe mercury levels
in their blood. Environmental Protection Agency scientists said
yesterday that new research had shown that 630,000 U.S. newborns
had unsafe levels of mercury in their blood in 1999-2000.
The key factor in the revised estimates is research showing differences
in mercury levels in the blood of pregnant women and their unborn
children. In a Jan. 26 presentation at EPA's National Forum on
Contaminants in Fish, in San Diego, EPA biochemist Kathryn R.
Mahaffey said researchers in the last few years had shown that
mercury levels in a fetus's umbilical cord blood are 70 percent
higher than those in the mother's blood.
"We have long known that the effects of methyl mercury on
the fetal nervous system are more serious" than on adults,
Mahaffey said in a telephone interview yesterday. "But we
did not routinely measure [umbilical] cord blood. We had thought
that the mother and the fetus had the same level."
Jane Houlihan, a vice president of the Environmental Working
Group, noted that the study "for the first time . . . calculated
the number based on children's blood levels, not mothers'. The
EPA analysis is showing that even if even if the mother is below
the danger zone, she can give birth to a baby that's over the
limit."
Mercury, a heavy metal, is a highly toxic substance that can
seriously damage neurological tissue. Poisoning can lead to learning
disabilities, lower intelligence and overall sluggishness. Fetuses,
infants and young children are especially vulnerable. Recent advisories
from EPA and the Food and Drug Administration have cautioned pregnant
women on the dangers of eating tuna and other large predatory
fish and shellfish, whose tissues absorb elevated levels of mercury.
EPA has said the largest U.S. sources of mercury contamination
are coal-fired power plants, whose annual atmospheric emissions
contain 48 tons of mercury. Much of it drifts into the ocean.
The Bush administration is proposing a new regulation requiring
power plants to cut mercury emissions 29 percent by 2007
and 70 percent by 2018. Environmental advocates say the
industry can achieve significantly deeper reductions.
Mahaffey, a top scientist in EPA's Office of Prevention,
Pesticides and Toxic Substances, said she began developing
her new estimates of the number of infants at risk by studying
research published last year from New Jersey and Maine.
The information helped her revise the formula used to extract
data from a survey conducted by the Centers for Disease
Control and Prevention in 1999-2000 on mercury levels in
pregnant women's blood.
The new formula showed that one out of six pregnant women
had mercury levels in their blood of at least 3.5 parts
per billion, sufficient for levels in the fetus to reach
or surpass the EPA's safety threshold of 5.8 parts per billion.
In 1999-2000, the last year for which government data are
available, this meant that 630,000 children were at risk
instead of the original estimate of 320,000.