The main health concerns from ingestion of long-chain PFAS, such as PFOS, PFOA, PFNA, and PFHxS, come from studies in laboratory animals which consistently show effects on the liver and immune system, and on growth, reproduction, and fetal development. PFAS can also affect the endocrine (e.g., thyroid) and hormonal systems and can disturb blood lipids such as cholesterol in lab animals. Studies of human populations exposed to elevated levels of PFOS, PFOA, PFNA, and PFHxS generally support the effects seen in animals. Some studies of populations exposed to PFOA have also shown an increased risk for kidney cancer, and at very high exposure levels, for testicular cancer. Our bodies eliminate these long-chain PFAS very slowly, so they can build up over time with continued exposure. Therefore, even low levels in drinking water may increase your risk of developing a variety of health effects if exposure is long term (months to years). Exposure to PFAS above the Connecticut Drinking Water Action Level does not necessarily mean that health effects will happen. Short-chain PFAS, such as GenX (replacement for PFOA) and perfluorobutane sulfonic acid (PFBS, a replacement for PFOS), do not build up in the body over time; however, they have been shown to cause similar health effects in laboratory animals as their predecessors.
PFAS are not readily absorbed by your skin, so bathing, showering, swimming, and washing dishes in water containing PFAS is not a significant source of exposure.