Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

and outdoor settings. Some of the screening levels developed to assess the sub­ chronic risks from the contaminants created by the WTC collapse were developed by adjusting emergency removal guidelines listed in EPA’s Hazard Evaluation Handbook to take into account shorter exposure periods. These guidelines are based on a 30-year exposure period and correspond to a 1-in-10,000 increased lifetime cancer risk for carcinogens.

Further, some of the benchmarks used to assess air quality and bulk dust in Lower Manhattan were criteria- or condition-based standards and not health-based standards. For example, the benchmark used to assess asbestos risk from WTC dust was developed to determine when asbestos containing material was subject to demolition and renovation regulations. For future disasters, health benchmarks are needed to address the types of exposures experienced at the WTC site, which included:

• acute or high concentration exposures up to 8 hours • sub-chronic (2 weeks to 1 year) exposures • indoor air exposures • exposure to asbestos • synergistic or multiple pollutant exposures

Details on each of the above benchmarks are in Appendix O.

We recognize that it is not possible to anticipate all the scenarios and develop standards that address all possible pollutants that may result from a disaster. Thus, we believe an agreed-upon framework for quickly developing additional guidelines and benchmarks in an emergency situation is needed. This process could include a panel of scientific experts that would be available in an emergency to analyze the available risk data and establish appropriate health-based benchmarks for the pollutants of concern

As discussed above, a multi-agency workgroup developed health-related benchmarks for six pollutants of concern related to indoor environment contamination from the WTC collapse that underwent peer review in October 2002. We believe the Agency should expand on these efforts to identify benchmarks for other pollutants of concern and for outdoor and indoor exposures based on threat assessments discussed earlier in this chapter. Related to this effort, EPA should collect information on background levels (i.e., pollutant concentrations under normal conditions), to properly assess the impact that a disaster has on the concentration of these pollutants of concern in the environment.

61 Report No. 2003-P-00012

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