Pregnant women in Brooklyn with high levels of certain compounds used in makeup and soaps were more likely to have preterm births and babies that weighed less, according to a new study.

The study, published online last week in the Journal of Hazardous Materials, provides the first evidence that germ-killing and preservative chemicals used in cosmetics and soaps might impact newborns’ health. It also bolsters suspicions that chemicals in soaps and lotions disrupt people’s endocrine systems, which are crucial for reproduction and babies’ development.

“The endocrine system is responsible for releasing chemicals that regulate growth and development, and these chemicals are really important during fetal maturation,” said Laura Geer, associate professor and environmental health scientist at SUNY-Downstate Medical Center in New York and lead author of the study.

Industry representatives, however, said that the study didn’t determine where the exposure to the chemicals came from and that preservatives in makeup make them safer for people.

From 2007 to 2009, Geer and colleagues tested 185 mothers’ third trimester urine, as well as the umbilical cord blood of 34 of them, for a suite of different parabens, used mostly in cosmetics, and triclosan and triclocarban, which are used as antimicrobials in soaps. The mothers were from the University Hospital of Brooklyn’s Prenatal Clinic.

Women with higher levels of butylparaben, a preservative in cosmetics, were more likely to have babies with decreased birth weights and preterm births. Higher levels of propylparaben, used in lotions and creams, were associated with decreased body lengths in the newborns.

Triclocarban, an antibacterial used in soaps and lotions, was linked to births happening earlier in the pregnancy.

The chemicals, especially the parabens, are common: According to the Environmental Working Group’s Skin Deep database, butylparaben is used in 2,245 personal care products, propylparaben is used in 7,212, and triclocarban is used in 21.

The results don’t prove that the chemicals are behind the birth problems. While scientists know the chemicals have some biological activity, the amount of exposure that could cause problems remains unclear.

Animals exposed to the chemicals have had some reproductive impacts. In rats, triclocarban impacted male sex organ development in a 2008 study. Paraben exposure decreased male rat sperm counts and efficiency in a 2002 study. One of the most studied endocrine disrupting chemicals, bisphenol-A or BPA, has been linked to multiple birth defects.

Kurunthachalam Kannan, a professor at the New York State Department of Health’s Wadsworth Center, said there are two plausible ways endocrine disrupting compounds could impact fetal growth: through oxidative stress or through estrogen receptors.

Linda Loretz, chief toxicologist at the Personal Care Products Council, said that parabens, used as preservatives, actually keep makeup safer by preventing microorganisms. She said such chemicals have been deemed safe by the Cosmetic Ingredient Review, which tests cosmetics’ ingredients. The Review is funded by the Personal Care Products Council.

She added Geer’s study was “pretty limited.”

“They didn’t determine where exposures came from,” she said.

Some of the compounds tested had what Geer referred to as “protective” effects, meaning higher levels of the pollutants meant increases in metrics such as birth weights.

“They saw both adverse and protective effects, which makes you wonder if it’s more noise than real effects,” Loretz said.  

Kannan also pointed out the researchers did not see any potential impacts from methylparaben, despite its similarity to butylparaben and the fact it was found at higher levels.  

Geer said it’s not surprising to see such disparities when looking at exposure to endocrine disruptors. Different chemicals act upon different hormones, which are responsible for different aspects of fetal development.

Nearly half the women tested were born outside the U.S., mostly from Caribbean countries and the rest mostly African American, Geer said. “We don’t know if there’s additional vulnerability … genetic or racial factors. Or there may be differences in terms of product use,” she said.