WTC asbestos wipe sampling and cancer risk analysis, December 2001

NYC 9/11 Public Portal Document

How to use Table 3

First, look for the health effect that will occur at the lowest levels of asbestos. This would be mesothelioma, a type of cancer that affects the cavity of the thorax, and also lung cancer if you are also a smoker. If a person inhales the equivalent of 0.00031 fibers of asbestos/milliliter of air for one year, then their increased risk of getting mesothelioma is 1 in a million. If they breathe 10 times that much for one year (0.0031 f-yr/mL), then the chance is increased to 1 in 100,000. Then, go over to the right hand columns which give a range of different time periods. Say you are interested in those exposures which will increase mesothelioma cancer risks by 1 in 10,000. A person would need to breath the following concentrations of asbestos for the following time periods to increase the risk by 1 in 10,000:

Total dose required to increase risk of mesothelioma by 1 in 10,000 fibers/miliaiter time period 1.616 1 week 0.124 3 months 0.062 6 months 0.031 1 year 0.0155 2 years 0.00062 50 years

If a different time period is needed than shown in the table, multiply the one-year cumulative exposure index by the time period. For 2 weeks, multiply by 14/365, etc.

Precautions when using Table 3

Confusion over the way asbestos is reported.

The first and foremost precaution in using Table 3 is this:

DO NOT CONFUSE ASBESTOS LEVELS REPORTED AS: “structures per square millimeter” ( s/mm’) WITH “structures per milliliter” ( s/mL)

These are very different things, although to the unwary, they appear to be the same. However, “structures per square milliliter” (s/mL) are the same thing as “structures per cubic centimeter” (s/cc^). See the last section of this memo for more information on the way asbestos levels are reported.

At its web site, EPA only reported concentrations as “structures/square millimeter.”" They could have given the asbestos concentration as “structures/milliliter” but did not. Thus, it is not easy to compare the EPA data unless you look at the actual lab sheets, which are posted on the internet at the NYELJP web site.'^

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