EPA memo re: asbestos assessment and Superfund advantages, Jan 2002

NYC 9/11 Public Portal Document

3.1% to 6.5%, with a mean of 5.6%. Because of the uncertainty from such limited data, if any conversion were to be made at this time for WTC fallout, then 20% of the total asbestos should be assumed to be PCM-equivalent.

No correction should be made for PCM-equivalents to asbestosis risks that were projected in the December 19 memo. This is because the ATSDR reviewed studies showing that asbestosis is associated with shorter asbestosis fibers.” In addition, it would probably be appropriate to use an uncertainty fector of 1000 for asbestos risks, according to CERCLA guidelines,’'* so that the risks I had previously projected in the December 19 memo for asbestosis would be 1000 times higher.

No correction should be made for the type of asbestos, chrysotile vs. amphibole vs. amosite, etc. This is because EPA does not recognize any difference in toxicity for the purpose of making risk assessments.”

Cancer risk level constituting an imminent and substantial endangerment to public health pursuant to Superfund

The EPA generally considers an upper-bound lifetime cancer risk to an individual of between 10 * and 10’® 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 IO"® 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 per 1,000,000. The National Contingency Plan (NCP) (Superfund) 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 any single individual affected by a site exposing humans to carcinogens exceeds 1 in 10,000 (the IO"* risk level) using reasonable maximum exposure assumptions for either the current or reasonably anticipated future exposures.’®

Cancer risks for Libby compared to Lower Manhattan

The December 20, 2001 risk assessment’’' prepared by Dr. Weis of EPA’s Carcinogen Assessment Group (CAG) found that for maximum concentrations of asbestos exposures to Libby residents through breathing suspended dusts inside residences, the cancer risk was between 1 in 1000 to 1 in 100. This cancer risk exceeded the threshold of 1 in 10,000 necessary to be considered an endangerment to public health.

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