The study, published in Environment International, found that using personal care products like nail polish, makeup and hair dye while pregnant or lactating is associated with significantly higher levels of per- and polyfluoroalkyl substances, known as PFAS, in blood plasma and breast milk.

“While PFAS are ubiquitous in the environment, our study indicates that personal care products are a modifiable source of PFAS,” said study author Amber Hall, a postdoctoral research associate in epidemiology at the Brown University School of Public Health. “People who are concerned about their level of exposure to these chemicals during pregnancy or while breastfeeding may benefit from cutting back on personal care products during those times.”

PFAS are synthetic chemicals that have been used in consumer products and industrial settings since the 1950s due to their ability to resist oil, water and heat. The study notes that PFAS have been associated with a range of adverse health effects, including liver disease, cardiometabolic and cardiovascular issues, and various cancers.

While several studies have detected these chemicals in personal care products directly, few have evaluated whether using these products impacts internal PFAS concentrations, Hall said. This is important, she added, because exposure to PFAS during pregnancy could contribute to adverse birth outcomes such as decreased birth weight, preterm birth, some neurodevelopmental disorders and diminished vaccine response in children.

Hall led a research team that analyzed data from the Maternal-Infant Research on Environmental Chemicals Study, which enrolled 2,001 pregnant people from 10 cities across Canada between 2008 and 2011. The researchers evaluated the contribution of the use of personal care products on PFAS concentrations in prenatal plasma (six to 13 weeks gestation) and human milk (two to 10 weeks postpartum). Participants reported frequency of use across eight product categories during the first and third pregnancy trimesters, one to two days postpartum, and two to 10 weeks postpartum.

In first-trimester pregnant people, the researchers found that higher use of nail care products, fragrances, makeup, hair dyes and hair sprays or gels was associated with higher plasma PFAS concentrations. Similar results were observed for third-trimester personal care product use and breast-milk PFAS concentrations at two to 10 weeks postpartum.

For instance, participants who wore makeup daily in the first and third trimesters had 14% and 17% higher plasma and breast-milk PFAS concentrations, respectively, compared to people who did not wear makeup every day. In addition, the researchers found that people using colored-permanent dye one to two days postpartum had higher PFAS levels (16% to 18% increases compared to never using them) in human milk concentrations.

Hall noted that the study examined only four types of PFAS among thousands that are used in industry and commerce. Thus, the study likely underestimated the extent of exposure to all PFAS from these products during pregnancy, she said.

Hall conducted the research with Joseph Braun, a professor of epidemiology and director of children’s environmental health at Brown University, who has been studying the health effects of PFAS for over a decade. Braun suggested that future studies examining how the use of personal care products affects PFAS exposure should consider differences by product type, as well as timing and frequency of use, or product formulation. This type of research can guide individual choices and also inform PFAS regulation, he said.

“Not only do studies like these help people assess how their product choices may affect their personal risk, but they can also help us show how these products could have population-level effects,” Braun said. “And that makes the case for product regulation and government action, so that we can remove some of the burden from individuals.”

The Maternal-Infant Research on Environmental Chemicals Study, which Braun helped to conduct, was supported by Health Canada’s Chemicals Management Plan, the Canadian Institutes of Health Research (MOP-81285) and the Ontario Ministry of the Environment.