Study of occupational lung cancer in asbestos factories in China

Our plain-English summary of Study of occupational lung cancer in asbestos factories in China, by H. Zhu, Z. Wang (British Journal of Industrial Medicine, 1993).

The study

• Authors: H. Zhu, Z. Wang
• Journal: British Journal of Industrial Medicine
• Published: 1993;50(11):1039-42
• Cited by: 25 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

A retrospective cohort study (1972-81) of occupational cancers in asbestos (chrysotile) factories has been previously published. In this paper the results of continued tracing and interviewing of members of this cohort from 1982 to 1986 is reported. The cohort included 5893 persons (45,974 person-years for men and 39,445 person-years for women). Malignant tumours played a large part in causes of death (36.9%). There were 183 cancers and 67 lung cancers among 496 deaths. The mortality due to lung cancer had a tendency to increase. By comparison with a control group, the RR of lung cancer was 5.32 (p < 0.01), and the SRR of lung cancer was 4.2 (p < 0.01), significantly higher than those of a control group. Among 148 cases of death from asbestosis there were 33 cases complicated with lung cancer (22.3%). The dose-response relations between exposure to asbestos and incidence of asbestosis and lung cancer were also studied in one asbestos factory. There was a positive correlation. A synergistic effect was found between cigarette smoking and lung cancer. Preventive and control measures and exposure limits for asbestos dust in the air of workplaces were recommended.

In plain English

This study extended follow-up of Chinese asbestos factory workers, first studied for 1972 to 1981, to the end of 1986. The factories used chrysotile asbestos. The authors traced 5893 people from eight factories who had worked there for more than 15 years, and compared them with workers not exposed to asbestos. There were 496 deaths: 183 from cancer and 67 from lung cancer (including two pleural mesotheliomas). Lung cancer death rates were 110.9 per 100,000 person-years for men and 40.6 for women. Compared with the control group, the relative risk of lung cancer was 5.3 (95% confidence interval printed as 2.6 to 7.1). By sex it was 11.7 for women, while the figure for men is printed as '5 8', apparently with a lost decimal point. Of 148 deaths from asbestosis, 33 were complicated with lung cancer. The average time from first employment to lung cancer was 23.91 years. Against workers with neither exposure, the relative risk was 1.8 for smoking alone, 3.8 for asbestos alone, and 11.3 to 17.8 for both, rising with amount smoked. The authors concluded that lung cancer remained the major cause of excess death.

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: Cohort study: a retrospective cohort (1972 to 1981) that was then followed prospectively from 1 January 1982 to 31 December 1986, with comparison to a control group of unexposed workers
• Who was studied: 5893 people from eight asbestos factories in China (the original cohort came from nine factories) who had worked there more than 15 years, traced to 31 December 1986; 45,974 person-years for men and 39,445 for women; follow-up rate 97.1%. The controls were workers not exposed to asbestos (122,021 person-years).
• Exposure: Work in chrysotile asbestos factories. Jobs named include treating crude material, handling, twisting, and repairing and maintaining. Workshop dust concentrations were collected, but no figures are given in this paper.
• Main results:
  • Among the 5893 asbestos workers there were 496 deaths (8.4%): 183 from cancer and 67 from lung cancer, which included two pleural mesotheliomas
  • Lung cancer mortality among the asbestos workers was 110.9 per 100,000 person-years for men (51 deaths in 45,974 person-years) and 40.6 per 100,000 person-years for women (16 deaths in 39,445 person-years) (Table 1)
  • Lung cancer in asbestos workers compared with controls: 67 deaths in 85,419 person-years (78.4 per 100,000) versus 18 deaths in 122,021 person-years (14.8 per 100,000). The relative risk was 5.3 (95% CI 2.6 to 7.1) and the attributive risk was 63.6, p less than 0.01.
  • Compared with controls of the same sex, the relative risk of lung cancer was 11.7 for female asbestos workers. For male asbestos workers it is printed as '5 8', apparently 5.8 with the decimal point lost in scanning, though no table confirms this figure (p less than 0.01)
  • The standardised relative risks for asbestos workers compared with controls were 2.7 for all cancers and 4.2 for lung cancer (p less than 0.01)
  • Of 148 deaths from asbestosis, 33 (22.3%) were complicated with lung cancer
  • The average latent period for lung cancer was 23.91 years (geometric mean): 23.41 for men and 25.57 for women
  • Lung cancer incidence by type of work was highest for workers treating crude material (193.8 per 100,000), then handling (144.8 per 100,000), then twisting (79.2 per 100,000)
  • Compared with people having neither exposure, smoking alone gave a relative risk of lung cancer of 1.8 and asbestos exposure alone gave 3.8
  • Asbestos exposure combined with smoking gave relative risks of 11.3 for light, 13.7 for medium and 17.8 for heavy smoking
  • The authors stated a positive dose-response relation between asbestos exposure and the incidence of asbestosis and lung cancer. They cite a separate publication for this, and the data are not shown in this paper.
• The authors' conclusion: The authors concluded that cancer was still the major cause of death and that lung cancer remained the major cause of excess death. They said they would recommend new health standards for asbestos dust in workplace air, and called for dust control, shorter working time, education of workers about smoking, and a ban on smoking in the workplace. They also suggested that lung cancer complicated with asbestosis be recognised in China as an occupational disease.

Topics

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

Medical terms in this study, explained in our Lexicon: Lung Cancer, Cohort Study, Chrysotile, Dose-response relationship, Synergistic Effect.

Related studies

• Study of occupational lung cancer in asbestos factories in China — R.W. Morgan, K.E. Zhao (1994)
• Analysis of mortality in chrysotile asbestos miners in China — L. Du, X. Wang, et al. (2012)
• Occupational and environmental cancer incidence and mortality in China — P. Li, S.S. Deng, et al. (2012)
• Lung cancer mortality from exposure to chrysotile asbestos and smoking: a case-control study within a cohort in China — E. Yano, X. Wang, et al. (2010)
• Cause-specific mortality in a Chinese chrysotile textile worker cohort — X. Wang, S. Lin, et al. (2013)
• Cause-specific mortality in relation to chrysotile-asbestos exposure in a Chinese cohort — S. Lin, X. Wang, et al. (2012)

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