US EPA

632460 

Book/Book Chapter 

Asbestos, all forms 

American Conference of Governmental Industrial Hygienists :: ACGIH 

1998 

American Conference of Governmental Industrial Hygienists 

Cincinnati, OH 

Documentation of the threshold limit values and biological exposure indices 

1 

A-1 - A-13 

TLV Recommendation
A TLV-TWA of 0.1 fiber/cc is recommended for all forms of asbestos. This TLV provides a good margin of safety in terms of asbestosis prevention. The weight of toxicological evidence supports the view that prevention of asbestosis will also prevent the risk of lung cancer.
In terms of mesothelioma, there are inadequate dose-response data, but the recommended TLV should also serve to prevent the risk of mesothelioma in workers.
The recommended TLV for the various forms of asbestos is for fibers greater than 5 um with an aspect ratio equal to greater than 3:1 as determined by the membrane filter method at 400 to 450X magnification (4-mm objective) phase-contrast illumination .
At this time, no STEL is recommended until additional toxicological data and industrial experience become available to provide a better base for quantifying on a toxicological basis what the STEL should be. The reader is encouraged to review the section on Excursion Limits in the "Introduction to the Chemical Substances" of the current TLV/BEI Booklet for guidance and control of excursions above the TLV-TWA, even when the 8-hour TWA is within the recommended limits.