Case-control study of pleural mesothelioma in workers with social security in Mexico

Our plain-English summary of Case-control study of pleural mesothelioma in workers with social security in Mexico, by G. Aguilar-Madrid, E. Robles-Pérez, C.A. Juárez-Pérez, et al (American Journal of Industrial Medicine, 2010).

The study

• Authors: G. Aguilar-Madrid, E. Robles-Pérez, C.A. Juárez-Pérez, I. Alvarado-Cabrero, F.G. Rico-Méndez, K.G. Javier
• Journal: American Journal of Industrial Medicine
• Published: 2010;53(3):241-51
• Cited by: 39 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Environmental and occupational exposure to asbestos in Mexico in the past has been a cause of deaths and health damages. Its magnitude is unknown to date. Our objective was to identify the proportion of cases of malignant pleural mesothelioma (MPM) that can be attributed to and occupational exposure to asbestos.

Methods: We carried out a case-control study of MPM in 472 workers insured by the Mexican Institute of Social Security, all Valley of Mexico residents, with 119 incident cases and 353 controls. Cases were histologically confirmed. Participants were questioned concerning their occupational history and sociodemographic data. Assignment to one of the four exposures was performed qualitatively by an expert hygienist. Odds ratios (ORs) and attributable risks (ARs) were calculated using a non-conditional logistic regression model.

Results: A total of 80.6% of cases and 31.5% of controls had occupational exposure to asbestos. ORs were adjusted for age and gender and by exposure category, and exhibited an increase with probability of exposure as follows: 3.7(95% CI 1.3-10.4) for the likely category and 14.3(95% CI 8-26) for the certain category; AR in the group occupationally exposed to asbestos was 83.2%, and the population AR was 44%.

Conclusions: Our results show that the relationship between industrial uses of all forms of asbestos is generating an increase in mesothelioma-related diseases and deaths among Mexican workers. As a public health policy, Mexico should prohibit the use of asbestos in all production processes with the aim of controlling the epidemic and preventing the occurrence of new cases of MPM.

2009 Wiley-Liss, Inc.

In plain English

This case-control study examined malignant pleural mesothelioma in Valley of Mexico workers insured by the Mexican Institute of Social Security. It compared 119 new, tissue-confirmed cases seen at two hospitals from May 2004 to April 2006 with 353 randomly selected healthy insured workers. Working from interview-based job histories, a single industrial hygienist who did not know which workers had the disease classed each person's occupational asbestos exposure as certain, likely, possible or none. Some exposure was found in 96 cases (80.6%) and 111 controls (31.5%). Adjusted for age and gender, and compared with no exposure, odds ratios were 14.3 (95% CI 8 to 26) for certain, 3.7 (1.3 to 10.4) for likely and 7.7 (2.8 to 21.2) for possible exposure. The authors estimated that 83.2% of cases among exposed workers (95% CI 72.7 to 89.6), and 44% in the population, were attributable to occupational asbestos. Stated limitations included reliance on one hygienist and missing asbestos monitoring data. The authors concluded that industrial use of all asbestos forms is generating more mesothelioma among Mexican workers, and called for a ban.

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 of incident malignant pleural mesothelioma
• Who was studied: 472 workers insured by the Mexican Institute of Social Security (IMSS), all residents of the Valley of Mexico: 119 incident, histologically confirmed cases of malignant pleural mesothelioma recruited at two IMSS hospitals, and 353 controls randomly selected from the IMSS insured-worker database. The study ran from May 2004 to April 20, 2006.
• Exposure: Occupational asbestos exposure was judged from interview-based work histories. One industrial hygienist, who did not know who was a case or a control, assigned each worker to one of four categories: certain, likely, possible or non-exposed. The authors stated that the exposure was probably chrysotile, the type most imported to Mexico.
• Main results:
  • Some occupational asbestos exposure (certain, likely or possible) was found in 80.6% (96) of cases and 31.5% (111) of controls.
  • Odds ratios compared with no exposure, adjusted for age and gender: 14.3 (95% CI 8–26) for the certain category and 3.7 (95% CI 1.3–10.4) for the likely category.
  • The adjusted odds ratio for the possible exposure category was 7.7 (95% CI 2.8–21.2).
  • Attributable risk among occupationally exposed workers was 83.2% (95% CI 72.7–89.6). The population attributable risk was 44%, and the article gives no confidence interval for that figure.
  • Duration of asbestos exposure of more than 13 years was found in 61% (59) of exposed cases and 38.7% of exposed controls, a statistically significant difference.
• The authors' conclusion: The authors concluded that industrial use of all forms of asbestos is generating an increase in mesothelioma-related disease and deaths among Mexican workers, and proposed that Mexico ban asbestos.
• Limitations the authors state:
  • Exposure was assessed by only one hygienist, which the authors said could introduce misclassification bias.
  • Exposure was hard to assign accurately in the intermediate (likely and possible) categories, which increases the chance of misclassification.
  • Reliable asbestos monitoring data do not exist in Mexico, so risk was likely underestimated.

Topics

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

Medical terms in this study, explained in our Lexicon: Case-Control Study, Pleural Mesothelioma, Occupational Exposure, Damages, Occupational History, Odds Ratio, Attributable Risk, Mesothelioma.

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