Federal law generally sets a floor, rather than a ceiling, when it comes to emission reduction regulations, and thus, when assessing a facility’s compliance and legal risks it is important to track state and local laws, regulations, and enforcement activities. This is particularly important for EtO, where several states have gotten ahead of EPA in setting state specific EtO risk thresholds and regulatory requirements.
As noted in our prior alert, public attention was drawn to EtO with the publication of the 2014 NATA in 2018, which identified many census tracts throughout the nation that merited further analysis for potential cancer risk associated with estimated EtO emissions. Because the existing federal NESHAP standards for industrial sources of EtO were all based on EtO unit risk estimates from before the 2016 IRIS EtO URE, and because EPA did not immediately propose to revise federal NESHAPs in light of the 2016 IRIS EtO URE and the 2014 NATA, many states have felt pressure to impose additional regulations on top of federal regulations. But in the absence of guidance from EPA on the meaning of the IRIS EtO URE and how to use it in the regulatory context (rather than in the preliminary risk screening context it was developed for), the result has been a complicated and contradictory patchwork of regulations that vary from state to state. Three basic approaches have emerged.