Unfinished business: the asbestos textiles mystery

Our plain-English summary of Unfinished business: the asbestos textiles mystery, by J.C. McDonald (The Annals of Occupational Hygiene, 1998).

The study

• Author: J.C. McDonald
• Journal: The Annals of Occupational Hygiene
• Published: 1998;42(1):3-5
• Type of article: Editorial, Review
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

In this invited editorial, the author reviewed evidence on why lung cancer risks among asbestos textile workers were much higher than expected from chrysotile exposure in other industries. He described two 1983 cohort studies of a textile plant in Charleston, South Carolina, of 1261 white males and of 2545 men. Using over 5000 impinger samples, both found closely similar linear exposure-response relationships for lung cancer (RR = 1 + 0.069 and 1 + 0.051 per mpcf.y). The plant used almost only chrysotile. Similar lung cancer findings came from a plant in Pennsylvania and a factory in Rochdale. The textile exposure-response slope was some 50 times steeper than in Quebec chrysotile miners and millers. Mesothelioma rates at Charleston (about 2 per 1000 deaths) were in line with Quebec. Possible explanations included exposure estimation errors, fibre size differences, smoking and mineral oil sprays; apart possibly from the oils, none seemed capable of reducing the difference below 10-fold. One lung burden study (161 samples) found similar fibre size distributions in Charleston and Thetford Mines except for tremolite fibres over 20 µm. Another (54 cohort members, 34 referents) found higher chrysotile and tremolite concentrations in workers. The author concluded that the remaining hypotheses, fibre length and mineral oil spray, were not well supported. He said the question remained unsolved after 15 years and needed far greater contributions from physical scientists and experimental toxicologists.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This invited editorial did not report new research. The author reviewed published studies on why lung cancer risk was so high among workers making asbestos textiles, a question the author called unexplained. The author described 1983 cohort studies of a textile plant in Charleston, South Carolina, which used mainly chrysotile. In one of these, 1261 white men had 35 lung cancer deaths, a standardized mortality ratio of 1.50. The author wrote that, for the same estimated exposure, the lung cancer risk rose about 50 times more steeply in textile workers than in Quebec chrysotile miners and millers. Mesothelioma did not show this difference. A lung tissue study by other researchers found similar fibre sizes in Charleston and Quebec workers, except for tremolite fibres longer than 20 micrometres, a difference the author called easily due to chance. The author judged that two explanations remained, fibre length and mineral oil spray, and that neither was well supported. The author concluded that the mystery remained unsolved and called for more work from physical scientists, occupational hygienists and toxicologists.

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: Invited editorial reviewing previously published cohort and lung fibre burden studies (no new data)
• Who was studied: Published studies of asbestos textile workers (Charleston, South Carolina; Mannheim, Pennsylvania; Rochdale) compared with Quebec chrysotile miners and millers and with other chrysotile industries
• Exposure: Mainly chrysotile (largely from Thetford Mines, Quebec, also Rhodesia) at the Charleston plant, with very small amounts of amosite and some crocidolite yarn. Tremolite contamination and mineral oil spray were discussed.
• Main results:
  • As reported by the author from Dement et al.: in the Charleston cohort of 1261 white males there were 35 lung cancer deaths by the end of 1975, a standardized mortality ratio of 1.50 against US rates
  • The author stated that the exposure-response slope for lung cancer in the textile industry was about 50 times steeper than in Quebec chrysotile miners and millers
  • From updated cohort data cited by the author: 2 mesothelioma deaths out of 1259 deaths from all causes (2/1000) in the Charleston cohort, compared with 38 of 8009 (5/1000) in the Quebec cohort
  • From the lung tissue study by Sebastien et al. (1989), cited by the author, comparing Charleston and Thetford Mines cohort members: the distributions of fibre lengths and widths were closely similar in the two cohorts, except for tremolite fibres over 20 micrometres
  • From the same Sebastien et al. study: 4 of 175 tremolite fibres (2.2%) from Charleston were longer than 20 micrometres, compared with 1 of 405 (0.2%) from Thetford. The author described this difference as easily due to chance.
  • From Green et al. (1997), cited by the author, comparing 54 Charleston cohort members with 34 matched reference autopsies: the geometric mean fibres per microgram of dried lung in cohort members compared with referents were 33.45 vs 6.71 for chrysotile and 3.56 vs 0.26 for tremolite
  • The author judged that two hypotheses remained, fibre length and mineral oil spray, and that neither was well supported
• The authors' conclusion: The author concluded that the high lung cancer risk in asbestos textile workers remained an unexplained mystery. The author judged that it might never be answered without greater contributions from physical scientists, occupational hygienists and experimental toxicologists.
• Limitations the authors state:
  • The author noted that peak exposures and fibre size distributions in ambient air had not been examined in the relevant cohorts
  • The author noted that the Green et al. lung fibre study was hard to interpret because it lacked denominators and times since last exposure, and because it was unclear how representative the small series was

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestos textiles, Chrysotile, Lung cancer.

Medical terms in this study, explained in our Lexicon: Asbestos Textiles, Lung Cancer, Chrysotile, Midget Impinger, Quebec Chrysotile, Mesothelioma, Thetford Mines, Tremolite.

Related studies

• Increased lung cancer mortality among chrysotile asbestos textile workers is more strongly associated with exposure to long thin fibres — D. Loomis, J.M. Dement, et al. (2012)
• Relationship of mortality to measures of environmental asbestos pollution in an asbestos textile factory — J. Peto, R. Doll, et al. (1985)
• Occupational cancer of the urinary bladder in dyestuffs operatives and of the lung in asbestos textile workers and iron-ore miners — G.M. Bonser, J.S. Faulds, et al. (1955)
• Updated mortality study of a cohort of asbestos textile workers — E. Pira, C. Romano, et al. (2016)
• Monitoring and Simulating Environmental Asbestos Dispersion from a Textile Factory — D. Kang, Y. Hwang, et al. (2018)
• Asbestos hazard evaluation in South Korean textile production — E. Johanning, M. Goldberg, et al. (1994)

Browse more research in The Annals of Occupational Hygiene, or return to medical research.