Women 16-49 at Risk of
Multiple Pollutants, Which Could Harm Brain Development of Fetuses and Babies
— In
a new analysis of thousands of U.S. women of childbearing age, Brown University
researchers found that most exceeded the median blood level for two or more of
three environmental pollutants that could harm brain development of foetuses
and babies: lead, mercury, and polychlorinated biphenyls (PCBs).
In a
recent study, more than half of women of childbearing age had median or higher
levels of at least two of three pollutants that could harm brain development.
Nearly 23 percent of American women of childbearing age met or exceeded the
median blood levels for all three environmental chemical pollutants -- lead,
mercury, and PCBs -- tracked in an analysis of data on thousands of women by
Brown University researchers. All but 17.3 percent of the women aged 16 to 49
were at or above the median blood level for one or more of these chemicals,
which are passed to fetuses through the placenta and to babies through breast
milk.
The
study, published in advance online Nov. 15 in the journal Environmental
Research, identified several risk factors associated with a higher likelihood
of a median-or-higher "body burden" for two or more of these chemicals.The three pollutants are of greatest interest
because they are pervasive and persistent in the environment and can harm fetal
and infant brain development, albeit in different ways, said study lead author
Dr. Marcella Thompson. But scientists don't yet know much about whether
co-exposure to these three chemicals is more harmful than exposure to each
chemical alone. Most researchers study the health effects of exposure to an
individual chemical, not two or three together.
"Our
research documents the prevalence of women who are exposed to all three of
these chemicals," said Thompson, who began the analysis as a doctoral
student at the University of Rhode Island College of Nursing and has continued
the research as a postdoctoral research associate for Brown University's
Superfund Research Program with co-author Kim Boekelheide, professor of
pathology and laboratory medicine. "It points out clearly the need to look
at health outcomes for multiple environmental chemical co-exposures."
Most
of the childbearing-age women -- 55.8 percent -- exceeded the median for two or
more of the three pollutants.
Risks
of exposure
Data
were collected between 1999 and 2004 from 3,173 women aged 16 to 49 who
participated in the Centers for Disease Control and Prevention National Health
and Nutrition Examination Survey (NHANES). The survey was designed to represent
the national population of 134.5 million women of childbearing age. Because the
original study also elicited a wide variety of information on health behaviors,
socioeconomic and demographic characteristics, Thompson and Boekelheide were
able to identify specific risk factors associated with increased odds of having
higher blood levels of lead, mercury, and PCBs.
They
found several statistically significant risk factors. The most prominent among
them was age. As women grew older, their risk of exceeding the median blood
level in two or more of these pollutants grew exponentially to the point where
women aged 30 to 39 had 12 times greater risk and women aged 40 to 49 had a
risk 30 times greater than those women aged 16 to 19.
Thompson
said women aged 40 to 49 would be at greatest risk not only because these
chemicals accumulate in the body over time, but also because these women were
born in the 1950s and 1960s before most environmental protection laws were
enacted.
For
further information visit: http://www.sciencedaily.com/releases/2012/11/121128143944.htm
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