OSHA: The 1972 Standard for Asbestiform and non-Asbestiform

Because the 1972 standard did not distinguish between asbestiform and non-asbestiform ATA, OSHA began to inspect employers whose employees were exposed to either mineralogic variety.

One supplier of industrial talc containing non-asbestiform anthophyllite and tremolite (the R.T. Vanderbilt Company) petitioned OSHA to restrict the application of the 1972 standard so that non-asbestiform anthophyllite and tremolite would not be covered by it.

In October 1974 OSHA interpreted the applicability of the asbestos standard to mean only asbestiform tremolite with and aspect ratio of 5 to 1.

However, because of preliminary information received from NIOSH regarding medical evaluations of workers exposed to tremolitic talc, FIM #74-92 was canceled on January 4, 1977. OSHA reverted to its regulatory definition of asbestos, which included all tremolite fibers, whether asbestiform or non-asbestiform.

In 1975 OSHA proposed to reduce the PEL and otherwise revise and tighten the asbestos standard to protect employees against carcinogenic effects of asbestos. No change was proposed concerning the six minerals defined as asbestos, but OSHA proposed to define "asbestos fiber" as a "particulate" instead of a "fiber" so as to stress its "morphology and toxicity * * * rather than its geologic or mineralogic origin."

It also proposed to add a three to one aspect ratio and a five micrometer maximum diameter to the definition of fiber in recognition of fiber respirability and the ACGIH recommended methods for fiber sampling and counting using phase contrast microscopy. No hearings were held on this proposal.

Courtesy of http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=PREAMBLES&p_id=784

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