ACGIH TLVs: a critical analysis of the documentation

Our plain-English summary of ACGIH TLVs: a critical analysis of the documentation, by P.A. Breysse (American Journal of Industrial Medicine, 1991).

The study

• Author: P.A. Breysse
• Journal: American Journal of Industrial Medicine
• Published: 1991;20(3):423-30
• Type of article: Comment, Letter
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This is a letter to the editor, not a research study. The author, writing as Chair of the American Conference of Governmental Industrial Hygienists (ACGIH) on behalf of its Board of Directors and Past Chairs, responded to a 1990 article by Roach and Rappaport. That article had argued that ACGIH threshold limit values (TLVs) for chemical substances are not true thresholds. The letter said the article studied a small, non-random sample: 70 of a possible 488 substances from the 1976 list and 29 of a possible 600 from the 1986 list. It also questioned the statistical methods. It said four of 28 examples were cited incorrectly or incompletely. One was asbestos: according to the letter, the full 1976 recommendation also stated that complete elimination of risk could not be assured for this or any other neoplastic (cancer-causing) agent. The letter reported that 1986 TLVs fully matched NIOSH recommended limits for 16 of the 29 substances. The author concluded that the article's sweeping conclusions were not appropriate. The author agreed with its suggestion to keep exposures below a small fraction (1/4 to 1/10) of the TLV.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Letter to the editor responding to and critiquing a published article (Roach and Rappaport, 1990); not an original research study
• Who was studied: No study population. The letter critiqued Roach and Rappaport's review of ACGIH TLV Documentations from 1976 and 1986. It also compared the 1986 TLVs for the 29 substances that article addressed with the 1989 NIOSH recommended exposure limits (RELs).
• Exposure: ACGIH threshold limit values for chemical substances in the workplace. Asbestos is one of the substances whose TLV citation the letter discusses; no fiber type is named.
• Main results:
  • The letter said Roach and Rappaport's 1976 analysis used TLVs for 70 of a possible 488 substances, and their 1986 analysis used 29 of a possible 600 substances, and that these were not chosen at random.
  • The letter said that of the 28 examples Roach and Rappaport took from the 1976 Documentation, four (asbestos, benzene, sulfuric acid and vinyl chloride) were incorrectly or incompletely cited.
  • For asbestos, the letter said the complete TLV recommendation was not cited. In addition to the interim exposure value, the ACGIH Committee had stated that complete elimination of risk could not be assured from this or any other neoplastic agent, because dose-response relationships were incompletely understood.
  • The letter said Roach and Rappaport misquoted sulfuric acid exposure levels from a 1952 study as 0.35-0.5 mg/m3, when the correct levels were 0.35-5.0 mg/m3, a 10-fold error.
  • The letter said Roach and Rappaport stated the early methyl chloride TLV as 20,000 ppm, whereas the Committee adopted 200 ppm in 1946, reduced it to 100 ppm in 1947, and the current value was 50 ppm.
  • Comparing the 1986 TLVs with the 1989 NIOSH RELs for the 29 substances, the letter reported complete agreement for 16 of 29 substances. Using Roach and Rappaport's correlation approach, it reported an excellent correlation between TLVs and RELs, with p less than 0.001. For all but four of the 16 substances where the two limits were equal, Roach and Rappaport had reported effects at or below the limit.
• The authors' conclusion: The authors concluded that Roach and Rappaport's sweeping conclusions were not appropriate. They gave four reasons: a limited, nonrepresentative sample of TLVs; questionable statistical analyses; errors in quoting TLVs; and errors in interpreting results. They said Roach and Rappaport's suggestion to keep exposures below a small fraction (1/4 to 1/10) of the TLV was consistent with the TLV Committee's primary prevention philosophy.

Related studies

• Time to reconsider TLVs — L. Djerassi (1988)
• Re: "TLVs for asbestos" — G.V. Coles (1993)
• Re: "TLVs for asbestos" — T.F. Mancuso (1993)
• Re: "TLVs for asbestos" — G.W. Schepers (1993)
• The role of threshold limit values in U.S. air pollution policy — J.C. Robinson, D.G. Paxman (1992)
• The limits of thresholds: silica and the politics of science, 1935 to 1990 — G. Markowitz, D. Rosner (1995)

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