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“Exposure to the GenX compound HFPO-DA may cause a range of adverse effects during pregnancy, according to a rodent study by researchers from the US National Toxicology Program (NTP). 

They exposed pregnant mice either to PFOA or GenX (hexafluoropropylene oxide dimer acid; HFPO-DA). PFOA has already been associated with adverse pregnancy outcomes in mice and humans, including reduced birth weight. But little is known about the effects of HFPO-DA, a later generation short-chain PFAS, which has been detected in river water worldwide.

Both PFOA and GenX (see box) resulted in:

  • increased gestational weight gain;
  • higher maternal liver weights;
  • adverse microscopic changes in the maternal liver;
  • abnormal lesions in the placenta;
  • higher placental weights; and
  • reduced embryo-placenta weight ratios.

Even the study’s lowest GenX dose (2mg/kg/day) caused significant adverse effects. 

The researchers are particularly interested in the finding that it appears to travel across the placenta, leading to higher placental weight and lower embryo-placenta weight ratios in mice exposed to higher doses. They suggest that maternal exposure to PFOA or GenX could cause a condition known as placental insufficiency. 

The work raises the wider issue that the placenta is rarely evaluated in reproductive toxicity studies. This is despite the fact that epidemiological studies suggest that disproportionately large placentas increase the risk of adverse health outcomes, including the likelihood of developing cardiovascular disease. 

Led by Suzanne Fenton from the National Institute of Environmental Health Sciences (NIEHS), which hosts the NTP, the researchers suggest that future studies should investigate adverse effects at levels below the study’s lowest GenX dose…”