Banned, contemporary chemicals widespread in U.S. pregnant women.

Jan 14, 2011

Woodruff TJ, AR Zota, and JM Schwartz. Environmental chemicals in pregnant women in the US: NHANES 2003-2004. Environmental Health Perspectives

Synopsis by Ami Zota, Sc.D

U.S. pregnant women are exposed to multiple and varied chemicals – some long banned, others currently used – that may harm the fetus during sensitive periods of development.

A new study finds for the first time that the bodies of virtually all U.S. pregnant women – and possibly their unborn children – carry multiple chemicals, including some banned since the 1970s and others used in common products such as non-stick cookware, processed foods and personal care products. 

While the Centers for Disease Control (CDC) has published previous reports on chemical levels in the general population, this is the first study to look at a broad range of chemicals specifically in pregnant women.

Researchers analyzed the data for 163 chemicals and detected about three-quarters of them at varying levels in some or all of the women. They found almost all – 99 to 100 percent – of the pregnant women carried polychlorinated biphenyls (PCBs), organochlorine pesticides, perfluorinated compounds (PFCs), phenols, polybrominated diphenyl ethers (PBDEs), phthalates, polycyclic aromatic hydrocarbons (PAHs) and perchlorate.

Other chemicals detected in the study group were PBDEs – compounds used as flame retardants and now banned in many states, including California – and DDT – an organochlorine pesticide banned in the United States in 1972. DDT was found at lower levels and in fewer women than its breakdown product DDE.

The health risks for mother and child associated with exposure to this many chemicals at detectable – and sometimes high – levels is not known. Low-level exposures to some of these chemicals during the prenatal period – a time of rapid growth – can lead to a host of long-term health effects, including birth defects, reproductive problems, and cancer. 

Surprisingly, DDE – a breakdown product of the long-banned DDT pesticide – was found in every woman and at some of the highest levels measured for any of the chemicals. Other chemicals found at high levels include perfluoroctane sulfonic acid (PFOS), which is found in food packaging and non-stick cookware (Correction, 1/19/2011: waterproof clothing and stain repellent treated carpets); triclosan, found in antibacterial soap and products; and mono-ethyl phthalate (MEP), found in cosmetics and fragrances. Animal or human studies show all of these chemicals can interfere with the endocrine system.

What these results imply for the women's health – or the health of the developing fetus – is not clear. Although the chemicals found are similar to those identified previously in nonpregnant women, pregnant women are more vulnerable than the general population. Many of the pollutants measured in the study can pass through the placenta from the mother to the developing fetus. They have been measured in cord blood, fetal blood and amniotic fluid.

Many of the chemicals found in the women, though, are known to contribute to similar health problems. Broadly, these can include effects on the heart, immune system and reproduction. A more specific example is how low exposures to lead or mercury alone may only slightly increase the risk of adverse neurological effects while exposures to both of them at the same time can produce a higher risk. The cumulative health risk from exposure to such a broad range of compounds is just beginning to be studied.

The researchers from the University of California, San Francisco, used data from the National Health and Nutritional Examination Survey (NHANES) to determine if the 163 chemicals were in the blood or urine of 268 U.S. pregnant women sampled between 2003 and 2004. The CDC conducts NHANES every two years.

The authors recommend that future work should focus on understanding sources of exposure and the health impacts from exposures to multiple chemicals.


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