NYSDOH Lowers Vapor Intrusion Action Levels for TCE

As anyone who has gone through the New York State Brownfield Cleanup Program (BCP) is all too aware, the New York State Department of Health (NYSDOH) has an important role in the cleanup process. The NYSDOH is responsible for determining that work completed under the NYSDEC remedial programs are protective of public health for the intended use of the property.

The NYSDOH is often the critical regulator that BCP applicants have to satisfy during the remedial site cleanup process. The NYSDOH Bureau of Environmental Exposure Investigation will assign staff for each site to investigate the potential for human exposure from environmental contamination as well as coordinate and communicate health-related activities. NYSDOH reviews sampling results, work plans, investigation reports and remediation decision documents, and provide comments or recommendations to NYSDEC. While NYSDEC guidance indicates that the agency project managers will consult with and receive input from NYSDOH, the recommendations from NYSDOH will often drive investigation and remedial decisions.

Back in 2013, we reported that the NYSDOH has lowered its air guideline value for PCE from 100 to 30 micrograms per cubic meter of air (30 ug/m3). The air guidelines are used to evaluate if further action is warranted to address exposures to certain volatile organic compounds (VOCs). Recently, NYSDOH lowered its chronic TCE exposure standard to from 5 micrograms per cubic meter (5 ug/m3) to 2 micrograms per cubic meter (2 ug/m3). NYSDOH has also set 20 micrograms per cubic meter (20 ug/m3) as the default level for taking “immediate and effective action” to protect the fetuses of pregnant women in the first trimester of pregnancy.

The impact of the changes to the TCE air guidelines will likely be geographically expanded remedial investigations and additional remedial obligations such as installation of sub-slab depressurization systems (SSDS). What is unclear is if previously approved workplans at sites that have not yet obtained COCs will now need to be revised. The changes could possibly trigger reopeners for sites that have already obtained COCs for additional investigation or installation of an SSDS to address vapor intrusion or require extended/enhanced Operation, Maintenance and Monitoring if indoor air exceeds the revised TCE air guidelines.

NYSDOH reduced its TCE air guideline because of new information on TCE. In 2011, the federal EPA recommended a 2 ug/m3 reference concentration (RfC) which is the level of a chemical in air that is unlikely to cause harmful non-cancer health effects. Because NYSDOH policy has been to set a guideline for a chemical at an air concentration that is equal to or less than its RfC, NYSDOH replaced its old RfC with EPA’s revised RfC.

In the revised fact sheet, DOH indicates that it is particularly concerned about exposure during pregnancy to air concentrations higher than 20 ug/m3 especially during the first trimester because the major steps of heart development occur during this period and TCE may be a risk factor for fetal heart defects in humans. Thus, NYSDOH recommends taking immediate and effective action to reduce exposure when an air concentration is equal to, or above 20 ug/m3. In all cases, the specific recommended action depends on a case-by-case evaluation of the situation.

By way of comparison, the EPA Region 9 office recently published Interim TCE Indoor Air Response Action Levels for residential and commercial/industrial exposure scenarios to address non-cancer risks posed by exposure to TCE. The EPA Region 9 TCE “urgent response action level” (interim measures implemented and completed within days) is 6 ug/m3 for residential exposures, 24 ug/m3 for commercial exposures for 8-hour workdays and 21 ug/m3 for 10-hour workdays. The EPA Region 9 “accelerated response action level” (interim measures completed with a few weeks) is 2 ug/m3, 8 ug/m3, and 7 ug/m3, respectively. Meanwhile, EPA Region 10 office has also established a short-term (21-day) non-cancer residential exposure of 2 ug/m3 while the commercial/industrial exposure setting is set at 8.4 ug/m3. Both of these regional offices have adopted a cancer risk chronic (lifetime) level of .43 ug/m3 and chronic non-cancer level of .21 ug/m3 for residential settings with the commercial/industrial settings set at 3.0 ug/m3 and .88 ug/m3, respectively. It should be noted that the use of the non-cancer risk level for TCE is very controversial and EPA is facing litigation over

DOH cautions that the air guideline is not a bright line between TCE concentrations that cause health effects and those that do not. The guideline was set at an air concentration that is lower than air concentrations known to cause, or suspected of causing, effects in humans and animals. Thus, exposure to concentrations above, but near the guideline, is not expected to cause health effects in people. In addition, the guideline is based on the assumption that people are continuously exposed to TCE in air all day, every day for months or as long as a lifetime. Continuous exposure is rarely true for most people, who, if exposed, are more likely to be exposed for a part of the day, part of a week, or part of their lifetime.

NYSDOH has developed two decision matrices to provide guidance about actions that should be taken to address current and potential exposures related to soil vapor intrusion. Actions recommended in the matrix are based on the relationship between sub-slab vapor concentrations and corresponding indoor air concentrations. NYSDOH is in the process of updating its matrices to reflect the changes to the TCE and PCE air guidelines.

EPA recently issued new VI guidance which is available Here. Look for a future post discussing the revised EPA VI guidance.

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