Fetuses may be exposed to antimicrobial compounds

By way of the umbilical cord, babies in the womb may receive doses of antimicrobial compounds, including the controversial and ubiquitous chemical triclosan. Though scientists do not know whether the exposures pose any risk to mother or child, animal studies have linked some of the compounds to hormone disruption.

The evidence for the compounds’ effects on human health is still murky, says epidemiologist Paul Terry of the University of Tennessee in Knoxville. But, he adds, “It’s always a concern when you see levels in what could be vulnerable populations — and that’s pregnant women and fetuses.”

In a study of more than 180 pregnant women in Brooklyn, N.Y., every woman had triclosan, a common ingredient in products such as soaps and toothpastes, in her urine. Triclocarban, a related compound also found in personal care products, was present in nearly 87 percent of samples. The researchers also looked for five parabens, a group of antimicrobial chemicals used as food additives and preservatives in cosmetics. All of the women were exposed to at least one of the five compounds.

The scientists, led by public health researcher Rolf Halden of Arizona State University in Tempe, then collected cord blood samples from around 30 of the women when they gave birth. All of the cord blood samples contained at least one paraben. About half of the samples contained triclosan and nearly a quarter contained triclocarban. Because cord blood acts as a conduit between mother and baby, the result suggests direct exposure to the baby. The paraben results were presented August 10 at the national meeting of the American Chemical Society in San Francisco and the triclosan and triclocarban data appeared in the Aug. 5 Environmental Science & Technology.

Previous surveys of urine samples in the United States have found similar levels of antimicrobials, with triclosan and parabens detected in the majority of people studied. But Halden cautions that even though researchers can detect exposure to a chemical, there aren’t necessarily effects on human health, and Halden and his colleagues have so far found no link between triclosan or triclocarban exposure and any negative health outcomes. However, the researchers did find that exposure to one particular paraben, butylparaben, was associated with slightly short body length and smaller head circumference at birth. Whether those differences mean anything for health is unclear, Halden says, and the study needs to be repeated with more babies.

In cell and animal studies, triclosan and triclocarban have been shown to disrupt hormone systems, which could potentially botch normal body development in children, promote cancer and alter fertility. Some studies have also linked parabens to hormone disruption and cancer, but clear evidence for human health effects has yet to be found.  

Although human health effects are uncertain, scientists know that use of such antimicrobial compounds promotes the spread of drug-resistant bacteria and potentially difficult-to-treat infections (SN: 5/17/14, p. 12).

The U.S. Food and Drug Administration is reviewing the safety of triclosan in personal care products. But for now, Halden suggests that consumers conduct their own cost-benefit analysis. The risks are unknown, Halden says, but compared with antibacterial soap, regular soap is just as effective at cleaning hands. Without any benefits, he asks, why take unknown risks?