Health effects of respirator use at low airborne concentrations

Our plain-English summary of Health effects of respirator use at low airborne concentrations, by J.H. Lange (Medical Hypotheses, 2000).

The study

• Author: J.H. Lange
• Journal: Medical Hypotheses
• Published: 2000;54(6):1005-7
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Respirators are considered a personal protective mechanism for preventing occupational disease because of inhaling toxic and hazardous substances. Engineering and work practice controls, in today's industrial environment, often maintain airborne contaminants below occupational hazardous levels. However, even at low concentrations, workers are often required to use respirators. Inappropriate use of respirators, during low exposure concentrations, may result in increased incidence and prevalence of disease from respirator use caused by physiological and psychological stress. This paper examines the hypothetical aspect of increased disease from using respirators at low exposure concentrations, with specific reference to the asbestos abatement industry.

In plain English

This was a hypothesis article reporting no new measurements or health data. The author proposed that requiring US asbestos abatement workers to wear negative pressure air purifying respirators below the OSHA Permissible Exposure Limit (PEL) of 0.1 fibers per cubic centimeter (time-weighted average) might increase disease through physiological and psychological stress. It drew on earlier studies of respirator physiology and of asbestos-exposed workers. A table gave estimated cancer mortality at several concentrations, from OSHA and from the author's own risk assessment. Beside these were hypothetical non-cancer mortality figures for respirator users. A footnote said these were the cancer figure multiplied by 3.57, a ratio of two standardized mortality ratios (375/105) from a 1979 study by Rubino and colleagues, not a measured respirator effect; some printed pairs do not fit this. At 0.1 f/cc, the OSHA-derived cancer figure was 2.3 × 10E-4 and the hypothetical respirator figure 8.2 × 10E-4. The author suggested limiting respirators to concentrations at or above the PEL, hypothesizing that users in low-contaminant settings will show more disease. The author noted possible confounding by smoking and other factors.

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: Hypothesis paper with no new data. It combines published findings with calculated, hypothetical mortality estimates.
• Who was studied: No study population. The paper concerns asbestos abatement workers in the United States in general.
• Exposure: Airborne asbestos at low concentrations (below the OSHA PEL of 0.1 f/cc-TWA), combined with use of negative pressure air purifying respirators (APRs). Table estimates cover 0.05 to 5.0 f/cc-TWA. No fiber type is specified.
• Main results:
  • The 'with respirator' figures are hypothetical non-carcinogenic mortality, not cancer mortality. The footnote says they were made by multiplying the cancer mortality estimate without a respirator by 3.57. That figure is a ratio of SMRs (375/105) relating non-malignant respiratory and cardiovascular disease to all malignant neoplasms, taken from Rubino et al (1979). It is not an observed comparison of respirator users and non-users. Some printed pairs do not follow the multiplication: at 0.5 and 1.0 f/cc in the risk-assessment columns, for example.
  • At 0.1 f/cc-TWA, OSHA-derived mortality from lung cancer, mesothelioma and gastrointestinal cancer was given as 2.3 × 10E-4 without a respirator. The hypothetical non-cancer figure with a respirator was 8.2 × 10E-4. The author's risk assessment gave 1.1 × 10E-5 (all cancer, without a respirator) and 3.9 × 10E-5 (hypothetical, with a respirator).
  • The author stated that the risk assessment estimate, compared with earlier OSHA estimates, suggests exposures at or below the PEL are not as hazardous as once thought. The author also noted that other studies, mostly at high exposure levels, contradicted this.
• The authors' conclusion: The author suggested that respirators be restricted to environments at or above the PEL. The author hypothesized that respirator users in low-contaminant environments will show more disease in future than non-users.
• Limitations the authors state:
  • The author noted that disease rates may be confounded by smoking, social and economic factors, poor safety practices and other substances.
  • The author noted that other occupational studies, mostly at high exposure levels, contradicted the suggestion that low exposures are less hazardous.

Topics

Medical terms in this study, explained in our Lexicon: Respirator, Occupational Disease, Abatement.

Related studies

• Safety and health of heavy equipment operators at Ground Zero — B.E. Lippy (2002)
• Workplace protection factors of HSE approved negative pressure full-facepiece dust respirators during asbestos stripping: preliminary findings — S.N. Tannahill, R.J. Willey, et al. (1990)
• Evaluation of respirator filters for asbestos fibers — Y.S. Cheng, T.D. Holmes, et al. (2006)
• Physiological and subjective responses to working in disposable protective coveralls and respirators commonly used by the asbestos abatement industry — M.K. White, T.K. Hodous, et al. (1989)
• Performance of power assisted respirators during simulated asbestos removal — M.P. Clayton, A.E. Bailey, et al. (2002)
• A study of personal and area airborne asbestos concentrations during asbestos abatement: a statistical evaluation of fibre concentration data — J.H. Lange, P.R. Lange, et al. (1996)

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