EPA memorandum on WTC dust wipe sampling and cancer risk

NYC 9/11 Public Portal Document I 917165954544 P.08/08 • • ’ *JUL-29-2002 17:57 FROM US EPA REGION 2 ORC TO I I I I Notes

1. As I noted in my April 25 letter, while the NCP authorizes EPA to take actions to address the release and threatened release of a hazardous substance into the environment. Section 300.400(i)(3) of the NCP states, “Activities by the federal and state governments in implementing this subpart are discretionary governmental functions. This subpart does not create in any private party a right to federal response or enforcement action. Tins subpart does not create any duly of the federal government to take any response action at any particular time.”

2. Many have commented that this risk range, used for remedial sites under CERCLA, is the one that should apply to the Indoor Air Residential Assistance Program - World Trade Center Dust Cleanup Program. As discussed elsewhere in this letter, EPA has developed a particularly stringent clearance level for asbestos in lower Manhattan residences. Nonetheless, for the following reasons, even if this were a remedial site, the 10’^ cancer risk - which is a “point of departure” referenced in the NCP - would not be used because it is impracticable to achieve. All protocols chosen for the Indoor Air Residential Assistance Program - World Trade Center Dust Cleanup Program are designed to reach die lowest level of detection that is reasonable with established methods. For asbestos, the sampling and analytical protocols chosen are designed to attain risk estimates of 1 x lO"^. To reach estimates of 1 x 10"^, extraordinary modifications would have to be employed to either significantly increase the volume of air being sampled or-to go to extraordinary expense to analyze many more grids on each sample filter. An increase in the sample volume, through an increase in flow rates from 10 to 15 liters/minute to 500 to 1,000 . liters/minute would lower the detection level. However, the only equipment available to operate at these rates are large units that are- impractical to bring into a residence. Achieving flow rates this high has not been tested using the sampling protocols, and there would be a high likelihood of compromising the sampling filters. To achieve detection levels consistent with 1 x 10’'’ risk values by running the equipment for longer periods of time would require increasing the period of sampling from 8 hours to 33 days. These two issues make it impractical to achieve a 1 x 10"'^ detection level.

TOTAL P.08

NYC-WTC_000151660