Risk is a combination of two factors: toxicity and exposure. If there is a bucket of very hazardous waste, but it's locked in a room where no one will ever be exposed to it, risk is low. Similarly, something like water is not toxic at all, so even at high exposure it has minimal risk.
EPA has set a chronic lifetime health advisory for drinking water of 70 parts per trillion, the level at which EPA has determined regular exposure over human life is unhealthy. OHA has developed its own health advisory levels for PFAS in drinking water that are lower than EPA's.
Not all types of PFAS have known health implications. The 2013-2015 analysis of all major public drinking water systems and some small systems tested for six types of PFAS. These six types are the ones for which there is established testing methodology and that have known harmful health impacts if a person is regularly exposed to them over the course of a lifetime. However, these six PFAS are a small subset of the 172 PFAS compounds that EPA now requires selected industries to report under the Toxics Release Inventory program, most of which do not yet have available toxicity information or testing methodologies. It's an even smaller subset of the 7,000+ known PFAS compounds.
DEQ will continue to work with EPA, OHA and other agencies to evaluate other PFAS screening tools to gain a more comprehensive understanding of potential PFAS risks in Oregon. Research has shown that many newer “short-chain" PFAS, which have been deemed safer than the older “long-chain" PFAS, can transform into the more toxic and persistent forms of PFAS in the environment, or through manufacturing processes or combustion. These scientific realities make managing PFAS as a class, rather than on a chemical-by-chemical basis, a more effective and efficient approach for reducing PFAS risks and impacts.
DEQ is continuing to investigate whether there are other ways humans are being exposed that could be monitored or controlled through existing DEQ programs. As more scientific research is produced on PFAS, risk determinations in Oregon may change over time.
According to the Agency for Toxic Substances and Disease Registry, the potential for health effects from PFAS in humans is not well understood. Some types of PFAS, such as PFOS, PFOA, PFHxS and PFNA, have generally been studied more extensively than other forms of PFAS. In general, studies have found that animals regularly exposed to PFAS at high levels resulted in changes in the function of the liver, thyroid, pancreas and hormone levels.