Toxic Chemicals Can Pass From Pregnant Woman To Child

Two new studies have provided even more evidence that toxic chemicals used in everyday products contaminate the bodies of pregnant women, who pass the chemicals on to their fetuses before birth.

In exciting new research, scientists from the Harvard School of Public Health and the Centers for Disease Control (CDC) have published a study looking at exactly how much of certain chemicals move across the placenta to the fetus and how much they concentrate in breast milk. The Harvard and CDC scientists and their collaborators recently published research that examined chemicals in 15 mother-child pairs, measuring to what extent the chemicals cross the placenta and reach the fetus. They measured a total of 87 chemicals and found nearly all of them in both mother and fetus. Average concentrations were highest in breast milk, and blood levels in mothers averaged 1.7 times those of the fetus.

In general, chemical levels correlated well between mother and fetus, indicating that the chemicals are crossing the placenta. One exception was the metal cadmium, which appears to accumulate in the placenta. Among other chemicals, structural differences such as number of bromine atoms or carbon chain length affected their ability to cross the placenta. Interestingly, levels of some highly chlorinated dioxins were lower than expected in milk, suggesting that larger molecules are at least to some extent blocked from passage into milk.

The researchers studied moms and babies from the Faroe Islands, which lie between Great Britain and Iceland. This population was chosen because of their marine mammal consumption and consequent wide range of exposures to persistent toxic chemicals like PCBs, toxic flame retardants, and Teflon chemicals.

A January study from the University of California San Francisco (UCSF) makes it very clear that moms in the U.S. also carry these chemicals during pregnancy. Researchers identified toxics such as bisphenol A (BPA), lead, cadmium, the toxic flame retardants PBDEs, and other chemicals in 268 pregnant women.

The UCSF researchers analyzed data collected by the CDC, which tests thousands of Americans each year for the presence of toxic chemicals in their blood and urine. Previous studies—such as WTC’s Earliest Exposures study—have examined smaller populations of women for specific chemicals, but this was the first time researchers have used the large data set collected by the CDC to assess pregnant women’s exposures.

Many of the chemicals were found in nearly all the pregnant women tested, and in most cases these chemicals are known to cross the placenta and expose the fetus during development. For example, the Teflon chemicals PFOA and PFOS were in 99% of pregnant women, and 96% tested positive for BPA.

The researchers wrote in the study, “Our analysis of the NHANES pregnancy data finds ubiquitous exposure to multiple chemicals during a sensitive period of development.”

Some chemicals, such as the rocket fuel chemical perchlorate, were present at higher levels in pregnant women; others were found at similar or lower levels. Changes during pregnancy such as higher blood volume and changed concentration of blood proteins are likely to affect how the women metabolize chemicals and ultimately their concentration.

The authors raised the concern that these chemicals may well be present at levels that are negatively affecting fetal development. The study’s lead author, Dr. Tracey Woodruff, said, ““Several of these chemicals in pregnant women were at the same concentrations that have been associated with negative effects in children from other studies.”

Image courtesy of flickr user jmayer1129