Memorandum on asbestos wipe sampling and cancer risk estimation, December

NYC 9/11 Public Portal Document

ESTIMATING INCREASED HEALTH RISKS FROM VARIOUS WTC EXPOSURE SCENARIOS

The following represents my efforts as a staff scientist to characterize any elevated health risks from exposures to WTC asbestos-contaminated dusts. As stated at the beginning of this memorandum, this risk assessment does not represent any official EPA analysis or position and does not necessarily reflect EPA policy. It has not been reviewed by EPA. There are many alternate ways to perform a risk assessment other than the one presented below. This risk assessment has a wide range of uncertainty both because of the limited data and the many assumptions that were utilized.

The EPA does not consider any exposure to a man-made carcinogen to be acceptable, but does base its actions in existing exposure situations according to the degree of elevated risk. The EPA chooses a degree of protection, or risk level, as a criteria for abating exposures.

The EPA generally considers an upper-bound lifetime cancer risk to an individual of between 10'’ audio** as a safe range. A risk of 10** represents a probability that there may be one extra cancer case in a population of 10,000 (1 per 10,000). A 10* risk is the probability that there may be one extra cancer case in a population of one million people over a lifetime of exposure (1 p^* 1,000,000. The National Contingency Plan (NCP) (Superftmd) requires that the 10* risk level should be the point of departure; the goal in any response by the EPA to ameliorate exposures to carcinogens from man-made sources. A response action is generally warranted if the cumulative excess carcinogenic risk for ary single individual affected by a site exposing humans to carcinogens exceeds 1 in 10,000 (the 10* risk level) using reasonable maximum exposure assumptions for either the current or reasonably anticipated future exposures. '*

Scenario 1 - Volunteer at Ground Zero for two weeks

A person volunteered to provide refreshments to the rescue workers on die perimeter of Ground Zero for two weeks. The volunteer spent 12-hour days, going home to Brooklyn at night S/he stayed outdoors for the majority^of die time, but came inside to one of the adjacent evacuated hotels for shelter from the elements, to rest, and to eat. Approximately 3 hours per day were spent inside this building.

This person also lived/may live in an urban environment for a life of 85 years, with and exposure level of 6 X 10 * (0.000006) s/mL.”

From Table 2, the asbestos level inside the contaminated building near Ground Zero is estimated to be 10 s/mL, midway between the “passive” conditions tested in the high-exposure building near Ground Zero, and the level estimated for cleaning out a storage room.

The level at the refreshment stand on the perimeter of Ground Zero is estimated to be 0.16 s/mL, towards the high side of EPA’s air readings outdoors near Ground Zero in the month of October, but low for the month of September,. (Inlenet Version)

- 11 - J NYC-WTC_000151645