WTC asbestos wipe sampling and cancer risk analysis, December 2001

NYC 9/11 Public Portal Document

Predicting air levels if cleanup is inadequate

Air levels might also be predicted if the cleanup is inadequate. As discussed in my December 6 memorandum, the EPA determined that neither conventional nor HEPA vacuums were capable of removing significant amounts of asbestos from carpet. Only the wet-extraction HEPA vacuums removed the asbestos particles which adhere to the carpeting.® Even the wet-extraction HEPA vacuums did not remove all of the asbestos, only about 60%.

Thus, the same or similar levels of asbestos could remain in the carpets as their were before the cleanup. After cleanup, the air levels could remain as high as projected in Table 2. The dust in both of the apartments in the Ground Zero Task Force study (Table 2) was not that thick, only a fine dusting where you could still read the writing on papers on a table even in the high exposure building.. This small amount of dust could easily work its way into the carpet and remain.

(I have been informed that typically, in asbestos abatement, carpeting is removed and discarded because of the inability to remove all the asbestos. More documentation on recommendations and this practice is requested. Information on actually testing or test methods for asbestos contaminated carpeting is also solicited, [email protected])

CALCULATING TOTAL DOSE FROM ATSDR’s CUMULATIVE EXPOSURE INDEX

Cumulative, or total dose, found by ATSDR to be related to health effects

The Agency for Toxic Substances and Disease Registry (ATSDR) is part of the Centers for Disease Control. It develops toxicological profiles in response to the Comprehensives Environmental Response, Compensation, and Liability Act (CERCLA, or Superfund). These profiles are subjected to extensive review by the most prestigious scientists as well as being reviewed and commented upon by affected industries and the public. The ATSDR found that the “cumulative exposure,” or total dose, was valid for predicting the probability of suffering health effects from asbestos. There was no “threshold” or safe level.’

A number of researchers have found that the occurrence ofasbestosis and Ling cancer correlates with cumulative exposure (that is, the product of concentration [PCM fibers/mL] multipiied by years of exposure). Therefore, human exposures are expressed below as PCM f-yr/mL.

[A] number of other studies indicate that lung cancer risk is linearly related to cumulafive dose without any obvious threshold

In other words, it does not matter whether or not you got the same total dose over a short period of time at higher levels, or a long period of time at lower levels. The health effects will be the same. The ATSDR does explain that there is no absolute correlation of the total dose with health effects, but uses it as a valid method to evaluate health risks.

Table 3 lists some of the “cumulative doses” found by the ATSDR to be associated with asbestos health effects. The table also gives examples of what the air asbestos levels are required for different time periods to achieve this dose.

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