Hand-spinning chrysotile exposure and risk of malignant mesothelioma: A case-control study in Southeastern China

Our plain-English summary of Hand-spinning chrysotile exposure and risk of malignant mesothelioma: A case-control study in Southeastern China, by Z. Jiang, T. Chen, J. Chen, et al (International Journal of Cancer, 2018).

The study

• Authors: Z. Jiang, T. Chen, J. Chen, S. Ying, Z. Gao, X. He, C. Miao, M. Yu, L. Feng, H. Xia, W. Wu, R. Chen, K. Morinaga, J. Lou, X. Zhang
• Journal: International Journal of Cancer
• Published: 2018;142(3):514-523
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

While chrysotile has been commonly used by Chinese textile industry for many years, investigations on the association of chrysotile exposure with risk of mesothelioma in China are scarce. We conducted a case-control study in a county located at Southeastern China, including 46 cases and 230 individually matched controls. A semi-quantitative method based on experts' assessment was used for evaluating hand-spinning chrysotile exposure. Conditional logistic regression models were used to assess the association of asbestos exposure with risk of mesothelioma. We found that hand-spinning chrysotile exposure was associated with significantly elevated risk of mesothelioma, reaching OR =10 (95% CIs: 1.4-65) for possible exposure and 64 (12-328) for definite exposure. Our data suggested a dose-response relationship of chrysotile exposure duration with risk of mesothelioma, reaching 28 (6-134) for <6 years, 51 (11-247) for 7-17 years and 56 (9-351) for ≥18 years. A dose-response relationship of cumulative exposure index (CEI) with risk of mesothelioma was found, reaching 28 (6-137) for CEI at 0-0.5 fibers per milliliter years (f/mL-year), 36 (7-184) for CEI at 0.5-28.6 f/mL-years and 79 (14-451) for CEI > 28.6 f/mL-years. We found a dose-response relationship of chrysotile exposure duration and CEI with risk of mesothelioma in Southeastern China, adding valuable information on health hazards of chrysotile exposure in China where chrysotile is still used nationwide.

© 2017 UICC.

In plain English

This case-control study examined links between hand-spinning chrysotile asbestos, at plants or at home, and malignant mesothelioma in a Southeastern China county. It compared 46 patients diagnosed 1998-2011 at the county's largest hospital with 230 controls. Of the patients, 27 had pleural and 19 peritoneal mesothelioma; 83% were women. Controls from the same villages were matched by sex and birth date within five years. Two experts rated job exposure; relatives answered for most patients, who had died. The authors' sampling found no amosite or crocidolite in raw materials. Compared with unexposed people, the odds ratio was 10 (95% CI 1.4-65) for possible and 64 (12-328) for definite exposure. By years in exposed jobs, odds ratios were 28 (6-134) under 6 years, 51 (11-247) for 7-17 years and 56 (9-351) for 18 or more. By cumulative exposure, they were 28 (6-137) above 0 to 0.5, 36 (7-184) above 0.5 to 29 and 79 (14-451) above 29 f/ml-years. The authors concluded that their findings suggest chrysotile exposure is the main cause of mesothelioma there. They noted recall and selection bias.

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: Case-control study with individually matched controls (5 controls per case), analysed with conditional logistic regression
• Who was studied: 46 malignant mesothelioma cases diagnosed 1998-2011 at the largest hospital in a county in Southeastern China (27 pleural, 19 peritoneal; 83% women). They were compared with 230 living controls from the same villages, matched by sex and by date of birth within 5 years. Controls had no malignant tumor or other asbestos-related disease.
• Exposure: Occupational hand-spinning of chrysotile asbestos at plants or at home in the asbestos textile industry. Two experts rated exposure semi-quantitatively by probability, intensity, frequency, duration and cumulative exposure index (CEI, in f/ml-years). The authors' X-ray diffraction of raw materials from 18 plants found chrysotile with impurities and no amosite or crocidolite. Non-occupational exposure was not assessed.
• Main results:
  • Among the 46 cases, 27 (59%) had pleural mesothelioma and the rest had peritoneal mesothelioma. Women made up 83% of cases.
  • Among cases, 36 had definite asbestos exposure, 5 had possible exposure and 5 had no exposure. In the discussion, the authors state that 40% of controls were exposed to asbestos.
  • Estimated median airborne fiber concentration was 8.0 (2.9-13.2) f/ml for hand-spinning at plants and 0.6 (0.2-1.0) f/ml for hand-spinning at home.
  • Compared with unexposed people, the odds ratio for mesothelioma was 64 (95% CI 12-328) for definite exposure (36 cases, 75 controls).
  • Compared with unexposed people, the odds ratio was 10 (95% CI 1.4-65) for possible exposure (5 cases, 18 controls).
  • Compared with unexposed people, the odds ratio was 49 (95% CI 11-225) for high-intensity exposure and 53 (95% CI 11-263) for continuous exposure.
  • Odds ratios by duration of the exposed job, compared with unexposed people: 28 (95% CI 6-134) for under 6 years, 51 (11-247) for 7-17 years, and 56 (9-351) for 18 years or more.
  • Odds ratios by cumulative exposure index, compared with the unexposed reference group: 28 (6-137) for above 0 up to 0.5 f/ml-years, 36 (7-184) for above 0.5 up to 29 f/ml-years, and 79 (14-451) for more than 29 f/ml-years. Table 4 gives the categories as >0-0.5, >0.5-29 and >29.
  • Mesothelioma mortality in the county was 1.2 per million in 1998 and peaked at 21.7 per million in 2007.
• The authors' conclusion: The authors concluded that they found dose-response relationships between chrysotile exposure and mesothelioma risk. They stated that their findings suggest chrysotile exposure is the main cause of mesothelioma in Southeast China.
• Limitations the authors state:
  • Recall bias: exposure information for cases came mostly from relatives, who usually report fewer exposures. Most controls, by contrast, were alive and interviewed directly.
  • Possible selection bias from how controls were selected; cases came from a single hospital's case series.
  • Small case numbers prevented a separate analysis of chrysotile exposure and peritoneal mesothelioma.

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, Malignant Mesothelioma, Case-Control Study, Mesothelioma, Asbestos Exposure, Dose-response relationship, Cumulative Exposure.

Related studies

• Overexpression of fibulin-3 in tumor tissue predicts poor survival of malignant mesothelioma patients from hand-spinning asbestos exposed area in eastern China — Z. Jiang, W. Shen, et al. (2020)
• Genome-wide profiling reveals novel microRNAs in hand-spinning-specific chrysotile exposure — J. Jia, X. Guo, et al. (2019)
• 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)
• Asbestos textile production linked to malignant peritoneal and pleural mesothelioma in women: Analysis of 28 cases in Southeast China — Z. Gao, K. Hiroshima, et al. (2015)
• Follow-up study of chrysotile asbestos textile workers: cohort mortality and case-control analyses — J.M. Dement, D.P. Brown, et al. (1994)
• Plasma Fibulin-3 as a Potential Biomarker for Patients with Asbestos-Related Diseases in the Han Population — Z. Jiang, S. Ying, et al. (2017)

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