The CT DPH has derived individual health-based drinking water Action Levels (ALs) for four of the most widely studied PFAS that have also been detected in human blood more frequently and at much higher concentrations than other PFAS. These four compounds were included in our previous AL, “sum of CT 5” less than 70 ppt, set in 2016. The fifth compound, perfluoroheptanoic acid (PFHpA), lacks sufficient data to develop an individual AL. The current Action Levels are:
CT Drinking Water Action Level (parts per trillion, ppt)
|Perfluorooctane sulfonic acid (PFOS)||10|
|Perfluorononanoic acid (PFNA)||12|
|Perfluorooctanoic acid (PFOA)||16|
|Perflurohexane sulfonic acid (PFHxS)||49|
These Action Levels are based on the most sensitive, human-relevant effects seen in laboratory animals exposed to PFOS (immune effects); PFNA, PFOA (developmental effects); or PFHxS (thyroid effects). This new chemical-specific approach reflects the evolving scientific evidence on the toxicity of PFAS and is more protective of public health than our previous AL (sum of “CT 5” = 70 ppt). Also, the resulting individual ALs are within the range of drinking water guidance and standards more recently derived by another federal agency (Agency for Toxic Substances and Disease Registry, or ATSDR, 2018, 2020) and by other states, including most of our neighboring states.