(September 12, 2001): EPA Sets High Benchmark for Asbestos

EPA Region 2 decides that it will use a benchmark of 1 percent in determining whether the asbestos level found in outdoor dust samples collected in and around the WTC site constitutes a “level of concern.” The figure apparently derives from the National Emission Standards for Hazardous Air Pollutants (NESHAP) (see April 18, 1989), which defines products containing more than 1 percent asbestos by weight as “asbestos-containing materials” (ACM). The NESHAP one percent definition is not based on safety, but rather is the detection limit of the Polarized Light Method (PLM) for determining asbestos levels (see August 23, 1996 and see November 20, 1990). The EPA will be heavily criticized for selecting this percentage as its “level of concern” benchmark. Critics will argue:
The one percent value is arbitrary because it is not based on safety. Furthermore, it was meant to be applied only to solid asbestos-containing products that do not release emissions (like dust).
As the EPA has previously acknowledged, there is no safe exposure level to asbestos (see April 25, 1986) (see April 18, 1989).
Measuring dust by percentage weight does not allow one to accurately assess the risk to public health because it does not determine the number of asbestos structures in a given area. For example, a sidewalk coated with 4 inches of dust containing .5 percent asbestos is much more of a health risk than a tablespoon’s worth of dust on the ground containing 2 percent asbestos because the former obviously has many more structures of asbestos. A person walking on the street would inhale more asbestos fibers walking through the 4 inches of asbestos-contaminated dust than stepping on just the tablespoon’s worth. [Jenkins, 6/9/2002 ] In fact, the EPA has previously acknowledged in an official statement to the public that levels “of 1 percent or less could present a risk where there is enough activity to stir up soil and cause asbestos fibers to become airborne” (see June 18, 2001). Additionally, a study in 1995 on the health effects of vermiculite found that soils with an asbestos level of only 0.001 percent can result in air concentrations of 0.01 fibers per milliliter, which exceeds many times the EPA cancer risk level of 0.000004 f/mL (see 1995) that corresponds to a cancer risk factor of 10