EPA interim final report on WTC background study, April 2003

NYC 9/11 Public Portal Document

data and the NYCDOH/ATSDR indoor air pilot program [NYCDOH, 2002]. A concerted effort also was made to identify and review additional sources of WTC-related data fi-om other governmental agencies (e.g., U.S. Geological Survey, NYC Board of Education), academic institutions, environmental organizations, and the private sector.

A semi-quantitative screening process was performed on the collected sampling data. Based on firequency-of-detection, concentration and inherent toxicity, contaminants that exceeded health­ based screening levels for the ambient air (see Appendix B) were identified. Dioxin and PAHs were added to the COPC list by this process. In addition, building constituents with carcinogenic (asbestos) or irritant effects (fibrous glass, crystalline silica) that were consistently and significantly found in bulk debris and indoor dust samples were identified as COPCs [NYCDOH, 2002]. Finally, lead (Pb) was included based on a comparison of sampling data with existing regulatory standards. Collectively, the resulting group of contaminants are called “contaminants of potential concern” or COPCs in this report.

The list of COPCs is shown in the column at the left, below. Included for each COPC is a data summary that supports its inclusion on the list. For completeness, an additional list is included on the right containing substances that, for various reasons, have created concern, but on closer inspection, were either rarely detected in the ambient air and/or settled dust sampling around the WTC, or routinely found at concentrations below the health-based screening criteria presented in Appendix B.

COPCs Other Substances Lead Benzene PAHs PCBs Dioxin Chromium Asbestos Cadmiiun Fibrous Glass Manganese Crystalline Silica Mercury Particulate Matter Refi-actory Ceramic Fibers Mold

Lead and Combustion By-Products (PAHs, Dioxin)

Lead. EPA’s ambient air monitoring data detected lead in concentrations that exceeded 1.5 ug/m’ on five occasions fi-om September 18-27,2001. It should be noted that the National Ambient Air Quality Standard (NAAQS) for lead is 1.5 ug/m’, but is based on a three-month average. Since the ambient monitoring program began, no three-month average of the ambient air data for lead exceeded the NAAQS of 1.5 ug/m’. However, lead was more commonly found at concentrations that exceeded 0.1 ug/m’, the default value employed in EPA’s Integrated Exposure Uptake Biokinetic Model for Lead in Children [EPA, 1994]. This value represents the upper-bound of average of ambient airborne lead concentrations in urban environments. Additional support for including lead as a COPC was provided by a report that characterized the dust that settled over lower Manhattan after the WTC collapse [Lioy, 2002]. The lead

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