EPA Implements New Update to Regional Screening Levels

EPA has released a new update to its Regional Screening Levels (RSLs), which are likely harbingers of what’s to come from IDEM. The RSLs are developed using risk assessment guidance from the EPA Superfund Program, though their use is not limited to such sites.  They are widely used for site screening and as initial clean-up goals across most states, including Indiana.  IDEM utilizes EPA’s RSLs and toxicity information to put out its own guidance, with the main difference between the two being that IDEM uses a 1x10-5 risk threshold, compared to EPA’s more conservative screening threshold of 1x10-6.

There are multiple updates to the RSLs, from the usual spelling corrections to the new additions of EPA ID numbers for all of those chemicals not having a CAS number.  Those identification numbers can be located at the EPA’s Substance Registry Service here.  Notable are the toxicity changes based on IRIS (Integrated Risk Information System) updates, such as benzo(a)pyrene (a common SVOC contaminant) with associated relative potency factors, the trimethylbenzenes, ammonia, and ethylene oxide.  There also were multiple changes to various sections of the associated User’s Guide and FAQs.

For questions on how EPA or IDEM updates may affect your projects, please contact a member of our Environmental Law Practice, at 317 269 9330.

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