Mothers with gestational diabetes transferring harmful 'forever chemicals' to their fetus

By Dr. Ananya Mandal, MDJul 17 2019

Researchers from the University of Massachusetts have found that pregnant women with gestational diabetes have a higher rate of passing on harmful synthetic chemicals called PFAS (17 - per- and polyfluoroalkyl substances) to their unborn babies and thus risking their health.

The study comes from a detailed epidemiology study and is titled, “Physico-chemical properties and gestational diabetes predict transplacental transfer and partitioning of perfluoroalkyl substances.” The study is published in the latest issue of the journal Environment International.

The team wrote that PFAS compounds have been used in non-stick cookware, food packaging, stain resistant materias and water proof materials used in the kitchens since 1950s. They were also widely used in aqueous firefighting foams at the military training sites and made their way into water sources. These were termed “forever chemicals” because of their resistance to wear and tear and break down. Certain communities, especially those living in Massachusetts were exposed to these chemicals wrote the researchers. Youssef Oulhote, assistant professor of biostatistics and epidemiology at UMass Amherst and the study's corresponding author explained, “The contamination is all over the world. We find them even in polar bears.”

The team of researchers write that this is one of the largest epidemiological studies looking at the presence of these compounds in pregnant women and the risk of harmful health outcomes including cancers, hormonal problems, problems of the immune system and developmental delays in the children born from these mothers.

For this study thus, the team collected blood and umbilical cord samples from pairs of mothers and their babies living in Faroe Islands. For this study the team chose 2 Faroese cohorts of mothers and babies. The first birth cohort was 100 single births between 1999 and 2001 called the Cohort 3. The second birth cohort examined was 51 single births between 2008 and 2009 called the Cohort 5. The team explains that they chose Faroe Islands as these are located away from the coast of Northern Europe between Norway and Iceland. The population consumes a lot of whale and is genetically similar. They wanted a genetically as well as socially similar population to exclude other factors that may affect the results. Oulhote added, “Most importantly, they consume whale, which is high in the food chain, so it accumulates many of the contaminants.”

Faroe islands village Sydrugota. Image Credit: Leos Mastni / Shutterstock

These blood samples were examined by the researchers at the Sorbonne University in Paris, the University of Southern Denmark, the Faroese Hospital System and Harvard University. Maternal levels of the PFAS were measured by collecting blood samples from the mother at 32 weeks of pregnancy from Cohort 3 women and at 2 weeks after delivery from women in Cohort 5. Levels of the following were measured, “9 Perfluorocarboxylates (PFCAs): Perfluorobutanoate (PFBA), Perfluoro-n-pentanoic acid (PFPeA), Perfluorohexanoate (PFHxA), Perfluoroheptanoate (PFHpA), PFOA, PFNA, PFDA, PFUnDA, and Perfluorododecanoic acid (PFDoDA); 5 PerfluoroSulfonates (PFSAs): PFBS, PFHxS, Perfluorohexanesulfonate (PFHpS), PFOS (both linear [n] and branched [br] isomers), and Perfluorodecane sulfonate (PFDS); and 3 precursors (perfluoroalkane sulfonyl fluoride based substances): perfluorooctane sulfonamide (FOSA: both linear [n] and branched [br] isomers), perfluorooctane sulfonamidoacetic acid (NMeFOSAA), and N-ethyl derivative of perfluorooctane sulfonamidoacetic acid (NEtFOSAA),” wrote the researchers.

The team then looked at the level of the chemicals transferred across the placenta to the babies. Multiple PFAS compounds with different chemical and physical properties were found and the characteristics and health parameters of the mother and baby pairs were recorded. While some of the PFAS compounds have been stopped from the manufacturing units, these were not commonly found. Those found were those with short carbon chains that were assumed to be less toxic but had the capacity to accumulate within the body. They added that they “observed a U-shaped relationship between transplacental transfer ratios and carbon chain length for perfluorocarboxylates and perfluorosulfonates.”

Oulhote added that there have been studies showing the transfer of PFAS compounds from mothers to babies. This study looked specifically at the transfer rate of these chemicals from pregnant mothers with gestational diabetes. Oulhote said, “It's one of the most consistent results we got. There was up to a 50 percent greater transfer on average,” in mothers who were diagnosed with gestational diabetes. He added, “We hypothesized that diabetes mellitus alters the kinetic disposition and metabolism of these chemicals. We know this has been shown to happen with some drugs and some nutrients in previous studies.”

The team wrote, “Median transplacental transfer ratios were generally below 1, except for perfluorooctane sulfonamide (FOSA), and ranged between 0.36 for perfluorodecanoate (PFDA) and perfluoroundecanoate (PFUnDA) and 1.21 for FOSA.” The team wrote, “gestational diabetes was also a strong predictor of transplacental transfer ratios, with significantly higher transfer in mothers with gestational diabetes.”

The study researchers concluded that this study provided a “better understanding of the transplacental transfer and blood partitioning of a large number of PFAS compounds.” They added, “Results elucidate the importance of chemical structure for future risk assessments and choice of appropriate blood matrices for measurement of PFAS compounds.”

The study was supported by the National Science Foundation-National Institutes of Environmental Health Sciences Oceans and Human Health Program, wrote the researchers.