Last week, MassDEP released new guidance on how it is assessing exposures to TCE in light of EPA new assessment of TCE risks released in September 2011. The biggest issue is that concerns about fetal exposure have caused MassDEP to tighten the imminent hazard threshold for indoor air exposures to 2 ug/m3. That’s an order of magnitude reduction from the prior standard of 20 ug/m3.

MassDEP has apparently thus far taken the position that it is not planning on reopening closed sites based on the new IH criterion. However, they are going to be under a lot of pressure – including, based on my experience, from its own staff – to do so. If there really is a fetal exposure risk, how can they not?

The tension of course, is that incentives and finality matter. If sites can be reopened based on new risk criteria, such as the TCE IH criterion discussed here, then currently innocent parties will have one more reason not to invest in Brownfields, which means that some sites that would otherwise get cleaned up might remain contaminated. That’s not in anyone’s interest.

How should MassDEP balance the need to meet current risk criteria with the need for finality to encourage Brownfields cleanups and redevelopment? I’m sure that Ben Ericson, Assistant Commissioner for the MassDEP Bureau of Waste Site Cleanup, would love to hear your solutions to this conundrum.