Illinois has become the latest state to issue formal Health Advisories for a number of Per- and Polyfluoroalkyl Substances (PFAS). The Health Advisories are for four compounds—Perfluorobutanesulfonic (PFBS) (140,000 parts per trillion “ppt”); Perfluorohexanesulfonic acid (PFHxS) (140 ppt); Perfluorooctanoic acid (PFOA) (2 ppt); and Perfluorohexanoic acid (PFHxA) (560,000 ppt)—and the Illinois Environmental Protection Agency (EPA) was required to issue them after each chemical was detected in at least one public water system in the state.

Notable among the four Health Advisories is the 2 ppt level set for PFOA. In comparison, the Federal Health Advisory for PFOA is 70 ppt, which the U.S. EPA determined in 2016 was the level “at or below which adverse health effects are not anticipated to occur over a lifetime of exposure.” See 81 FR 33250 . 2 ppt is lower even than the relatively conservative drinking water standards set for the compound is states like Michigan (8 ppt) and New York and California (10 ppt).

Although the Health Advisory levels are not enforceable standards, they are legally significant. Where the Illinois EPA has issued a Health Advisory for a substance like these for which there is no enforceable groundwater standard, the State is required to consider the advisory level in a number of circumstances, including (1) when establishing groundwater cleanup or action levels following a release; (2) when determining whether a community water supply is taking its water from a source consistent with State siting requirements; and (3)during any rulemaking to set an enforceable standard. See 35 Il. Admin Code. § 620.601.

Does this mean Illinois is poised to enact the most stringent PFAS regulations in the country? Probably not. Under the Biden administration, The U.S. EPA will almost certainly be rolling out enforceable Maximum Contaminant Levels (MCLs) for various PFAS chemicals, including PFOA, in the near future. And that will likely take the pressure off Illinois and other states to put separate, more stringent standards into place. But these Health Advisories do reflect the seriousness with which state agencies are taking PFAS issues, and also how far views of what levels of PFAS are safe has come in the last several years, at least in some circles.