Chrysotile asbestos exposure: cancer and lung disease risks

Our plain-English summary of Chrysotile asbestos exposure: cancer and lung disease risks, by J.M. Dement (New Solutions, 1994).

The study

• Author: J.M. Dement
• Journal: New Solutions
• Published: 1994;4(4):5-8
• Read it: PubMed · Publisher

In plain English

The author updated a study of 1,247 white men who worked at least one month in textile production between 1940 and 1965 at a South Carolina plant where chrysotile was the only asbestos processed as raw fiber. With follow-up extended to 1990, deaths rose from 308 to 607. Compared with U.S. death rates, all-cause mortality was higher than expected (standardized mortality ratio, SMR, 1.44; 90% confidence interval 1.35 to 1.54). So was mortality from cancer (SMR 1.46; 1.26 to 1.68), non-malignant respiratory disease (SMR 2.24; 1.78 to 2.79) and respiratory tract cancer, mainly lung cancer (SMR 2.25; 1.85 to 2.71). There was an unexpected excess of liver, gall bladder and biliary tract cancer, based on 6 deaths (SMR 4.04; 1.76 to 7.97). Two death certificates recorded mesothelioma (one pleural, one peritoneal). Among workers with at least 15 years latency, lung cancer risk rose with cumulative exposure, to an SMR of 10 (2 deaths observed, 0.2 expected) above 100,000 fibers/cc-days. The author concluded this confirmed a steep exposure-response relationship for lung cancer and that the data gave no scientific basis for different public health policy for chrysotile.

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: Update and reanalysis of a retrospective cohort mortality study, adding 15 years of follow-up. This is a brief report; full methods were published elsewhere.
• Who was studied: 1,247 white male workers employed for at least one month in textile production operations between January 1, 1940 and December 31, 1965 at an asbestos textile plant in South Carolina. Vital status was followed to December 31, 1990, giving 44,131 person-years at risk.
• Exposure: Chrysotile asbestos, received from Quebec, British Columbia and Rhodesia, was the only type of asbestos processed as raw fiber in asbestos textile production. Exposure was estimated by plant area, job and calendar year, in fibers longer than 5 micrometers per cubic centimeter of air. It was summed as cumulative exposure in fibers/cc-days.
• Main results:
  • Among the white male cohort, deaths almost doubled from 308 to 607 with the update.
  • All-cause mortality was higher than expected based on U.S. death rates: SMR 1.44 (90% confidence interval 1.35 to 1.54).
  • There were statistically significant excesses for all cancer (SMR 1.46; CI 1.26 to 1.68) and diabetes mellitus (SMR 2.02; CI 1.17 to 3.28). Heart disease, cerebrovascular disease and accidents were also statistically significantly in excess.
  • Non-malignant respiratory disease was statistically significantly increased (SMR 2.24; CI 1.78 to 2.79). This was mainly due to pneumoconiosis (asbestosis) and other respiratory disease, primarily chronic obstructive pulmonary disease.
  • All respiratory tract cancer was statistically significantly increased (SMR 2.25; CI 1.85 to 2.71), primarily due to lung cancer.
  • There was an unexpected statistically significant increase in liver, gall bladder and biliary tract cancer (SMR 4.04; CI 1.76 to 7.97).
  • The liver, gall bladder and biliary tract cancer excess was based on 6 observed deaths (Table 3).
  • Cancers of the pancreas, gastrointestinal tract, kidney and larynx were in excess, but these excesses were not statistically significant.
  • Mesothelioma, one pleural and one peritoneal, was recorded on the death certificates of two white males. They had been employed at the plant for 25 and 32 years, with latency periods of 37 and 34 years. One death from 'cancer of the pleura' was recorded without mention of mesothelioma. A further mesothelioma after 1990, in a worker employed mostly in non-textile operations, was not included in the cohort.
  • Lung cancer risk rose with cumulative exposure among workers with at least 15 years latency. A statistically significant increase was first seen at 1,000 to 2,500 fibers/cc-days, and the SMR reached 10 among those exposed above 100,000 fibers/cc-days.
  • In the highest exposure group (above 100,000 fibers/cc-days), the SMR of 10.00 rested on 2 observed lung cancer deaths against 0.2 expected.
• The authors' conclusion: The author concluded that the updated results confirm earlier observations of a steep lung cancer exposure-response relationship among chrysotile textile workers, consistent with other chrysotile textile cohorts. The author also concluded that available epidemiological and animal bioassay data provide no scientific basis for differential public health policy for chrysotile.

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Asbestos Exposure.

Related studies

• An epidemiological study of the role of chrysotile asbestos fibre dimensions in determining respiratory disease risk in exposed workers — L. Stayner, E. Kuempel, et al. (2008)
• Occupational exposure to chrysotile asbestos and cancer risk: a review of the amphibole hypothesis — L.T. Stayner, D.A. Dankovic, et al. (1996)
• Nonoccupational exposure to chrysotile asbestos and the risk of lung cancer — M. Camus, J. Siemiatycki, et al. (1998)
• Health risk of chrysotile revisited — D. Bernstein, J. Dunnigan, et al. (2013)
• Relative risk of mesothelioma among railroad machinists exposed to chrysotile — T.F. Mancuso (1988)
• Mesothelioma risk from chrysotile — J.T. Hodgson, A. Darnton (2010)

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