Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

Appendix O

Details on Health-Based Benchmarks Needed

Acute Exposure Guideline Levels. EPA is responsible for a program involving entities inside and outside the government to develop Acute Exposure Guideline Levels (AEGLs). These guidelines are developed by the National Advisory Committee for Acute Exposure Guideline Levels for Hazardous Substances. The AEGLs address exposures to pollutants that last for 10 minutes, 30 minutes, 1 hour, 4 hours, and 8 hours, and are established to address three potential types of health impacts from these acute exposures: non-disabling, disabling, and death. This program has finalized a limited number of AEGLs; however, none of the finalized guidelines addressed the primary pollutants of concerns for Lower Manhattan after September 11. EPA’s Office of Research and Development and the Office of Prevention, Pesticides and Toxic Substances are currently working to establish needed AEGLs.

Sub-Chronic Guidelines. EPA also did not have sub-chronic guidelines for the contaminants found in Lower Manhattan on September 11. ATSDR defines sub-chronic as exposures lasting 2 weeks to 1 year. In general, EPA’s benchmarks have focused on lifetime cancer risk over a 30-year exposure period. Because sub-chronic guidelines did not exist for the WTC pollutants of concern, these 30-year benchmarks were adjusted to fit the situation found at WTC. For example, to assess sub-chronic (1 year) exposure to dioxin in the ambient air, EPA took the dioxin 30-year exposure benchmark and adjusted it to reflect a 1-year exposure by multiplying the 30-year exposure benchmark by 30. These guidelines should be developed, to the extent possible, before a disaster strikes so that the process can be properly peer reviewed and any necessary revisions made before they are needed.

Indoor Air Benchmarks. EPA also did not have risk-based indoor air or bulk dust benchmarks for the pollutants found in dust deposited indoors. A work group formed after September 11, consisting of officials from Federal, New York State, and New York City agencies, developed indoor air benchmarks for COPCs resulting from the WTC towers collapse. These benchmarks, identified in a document entitled “World Trade Center Indoor Air Assessment: Selecting Contaminants of Potential Concern and Setting Health-Based Benchmarks,” were initially published in draft in September 2002. The document was peer reviewed and a revised interim final version was published in April 2003. The COPC report could be used as a starting point in developing health benchmarks for additional pollutants that may be encountered in future disasters. EPA’s Homeland Security Strategy includes plans to identify chemical and biological substances for which indoor air reference levels (benchmarks) may be needed, and establish advisory indoor air reference levels for the substances identified.

Health-Based Benchmarks for Asbestos. As addressed in Chapter 2, health-based asbestos standards for indoor and outdoor air do not exist. The AHERA standard, used as a primaiy WTC benchmark to communicate asbestos risk for ambient air, is the filter background contamination level estimated when the TEM protocol was developed. Filters with smaller asbestos contamination levels are now available, so that smaller concentrations of asbestos can now be

113 Report No. 2003-P-00012

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