Re: "TLVs for asbestos"

Our plain-English summary of Re: "TLVs for asbestos", by T.F. Mancuso (American Journal of Industrial Medicine, 1993).

The study

• Author: T.F. Mancuso
• Journal: American Journal of Industrial Medicine
• Published: 1993;23(6):961-5
• Type of article: Comment, Letter
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This item was a letter to the editor, not a research study. The author, Thomas F. Mancuso, replied to a 1992 letter by Cook about asbestos litigation and the Threshold Limit Value (TLV) for asbestos of 5 million particles per cubic foot (mppcf). The letter presented no new data. It quoted historical documents from the ACGIH, NIOSH, OSHA, the IARC and other writers. The author argued first that the asbestos TLV was meant to prevent asbestosis, not cancer, citing the 1962 ACGIH documentation and the 1972 NIOSH standard. The author also quoted ACGIH history stating that TLVs were not sharp dividing lines between safe and harmful exposure. The main point disputed Cook's statement that compliance should have been judged on the percentage of asbestos in the dust. Citing the 1938 Dreessen study, ACGIH, NIOSH, Balzer and a 1986 letter from Cook, the author stated that the 5 mppcf value counted all dust particles, fibrous and non-fibrous. The author concluded that this TLV was for total dust and was not based on the percentage of asbestos.

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 replying to an earlier letter. It quotes historical documents and published literature and contains no original study data.
• Who was studied: No study population. The letter discusses the history of the ACGIH asbestos TLV and the dust measurements in the 1938 Dreessen study of asbestosis in the asbestos textile industry, on which the TLV was based.
• Exposure: Asbestos dust, as measured for the TLV of 5 million particles per cubic foot by impinger dust counts, first set by the ACGIH in 1946.
• Main results:
  • The author stated that the asbestos TLV was intended to prevent asbestosis, not cancer.
  • The author quoted the 1972 NIOSH recommended standard as designed primarily to prevent asbestosis.
  • The author quoted the 1976 IARC monograph as saying it was not possible to assess whether there is a level of human exposure below which an increased risk of cancer would not occur.
  • The author quoted an ACGIH historical review explaining that the word 'threshold' did not mean a sharp line between safe and injurious exposure.
  • The author quoted the 1962 ACGIH documentation stating that the Dreessen counts included both fibrous and non-fibrous particles, with non-fibrous particles greatly predominating.
  • The author stated that the ACGIH asbestos TLV, from 1946 onward, never specified a percentage of asbestos in the total dust count, unlike the TLV for silica.
  • The author quoted a 1986 letter in which Cook acknowledged that dust counts of that era included asbestos particles and particles of other composition.
  • The author quoted an unpublished 1947 Hemeon report stating that the available information did not give complete assurance that 5 million particles was safe.
• The authors' conclusion: The author concluded that the historical literature, including Cook's own 1986 letter, established that the 5 mppcf TLV for preventing asbestosis applied to total dust, fibrous and non-fibrous, and was not based on the percentage of asbestos, as Cook had asserted in 1992.

Related studies

• ACGIH TLVs: a critical analysis of the documentation — P.A. Breysse (1991)
• Re: "TLVs for asbestos" — G.V. Coles (1993)
• Re: "TLVs for asbestos" — G.W. Schepers (1993)
• Time to reconsider TLVs — L. Djerassi (1988)
• Mesothelioma: cases associated with non-occupational and low dose exposures — G. Hillerdal (1999)
• Corporate influence on threshold limit values — B.I. Castleman, G.E. Ziem (1988)

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