EPA report on WTC air monitoring and cleanup, April 2003

NYC 9/11 Public Portal Document \

of dust contamination as determined through visual inspection. If a visual inspection of the residence and the building’s common spaces (including elevator shafts) revealed minimal dust accumulations (light coating), “Scope of Work A” applied. If visual inspection indicated large or significant accumulations of dust or debris from the WTC collapse in residences, portions of the residence, or the Vi t J € rt t £ vUft-S building’s common spaces, “Scope of Work B” applied. In general, “Scope of J Jr 11 c ' <'5 A \ Work B” included additional cleaning of surfaces not included in “Scope of i A Appendix M describes the two approaches available for residents cleaning and post-cleaning testing.

A significant issue with respect to developing health-related benchmarks , Av* •^. (qj. clearance standards) is the extent of prior or background contamination, of txge, particularly in urban areas. This information is needed to determine the impact of / Vo 5? a disaster on the indoor environment. Studies have shown that these background / 4 cYs levels can exceed concentrations that may present a greater than 1-in-1,000,000 I excess lifetime cancer risk (foe desired cleanup goal for foe Superfund program). In foe WTC case, EPA’s background study of Upper Manhattan suggests foat background concentrations for asbestos in indoor air and dioxin in settled dust \ were at levels that presented a greater than 1 -in-1,000,000 excess cancer risk. (

V Concurrent with foe start of foe indoor cleanup, a multi-agency workgroup of .1. Federal, State and city officials identified contaminants of potential concern P(COPC) related to foe WTC collapse and developed health-related benchmarks for (Vx ^11 ^^e COPCs, including asbestos, lead, dioxin, PAHs, fibrous glass, and Il silica. Three of these COPCs are considered cancer causing: asbestos, Ago dioxin, and PAHs. For each of foe three carcinogens, foe v. crkgrcup established a V f ' o ©r\ ' health-related benchmark that equated to an increased lifetime cancer risk of 1 -in- a 10,000. This means foat if 10,000 people are exposed to a single COPC at foe ■ I <,U5 9®'^' 1 ^restablished benchmark level for 30 years, there may be one more case of cancer '*'1® vV ft than if the group had not been exposed. ( K September 2002, foe multi-agency workgroup published foese COPCs in a peer , oC. review draft entitled “World Trade Center Indoor Air Assessment: Selecting Contaminants of Potential Concern and Setting Health-Based Benchmarks,” which was peer reviewed by the Toxicology Excellence for Risk Assessment (TERA) organization in October 2002. TERA’s peer review report was issued on February 7,2003. The group’s suggestions included:

• Expanding the list of COPCs as appropriate, • More clearly explaining the methodology for selecting the COPCs, • Adding criteria to account for potential exposures through contact with dust in the risk-based screening for COPC selection, • Adding parameters for children’s exposure, and • More fully describing the approach for considering the health effects of mixtures of COPC.

49 Report No. 2003-P-00012

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