The INTEROCC case-control study: risk of meningioma and occupational exposure to selected combustion products, dusts and other chemical agents

Our plain-English summary of The INTEROCC case-control study: risk of meningioma and occupational exposure to selected combustion products, dusts and other chemical agents, by D.M. McElvenny, M. van Tongeren, M.C. Turner, et al (Occupational and Environmental Medicine, 2018).

The study

• Authors: D.M. McElvenny, M. van Tongeren, M.C. Turner, G. Benke, J. Figuerola, S. Fleming, M. Hours, L. Kincl, D. Krewski, D. McLean, M.É. Parent, L. Richardson, B. Schlehofer, K. Schlaefer, S. Sadetzki, J. Schüz, J. Siemiatycki, E. Cardis
• Journal: Occupational and Environmental Medicine
• Published: 2018;75(1):12-22
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Little is known about occupational risk factors for meningioma.

Objectives: To study whether risk of meningioma is associated with several occupational exposures, including selected combustion products, dusts and other chemical agents.

Methods: The INTEROCC study was an international case-control study of brain cancer conducted in seven countries. Data collection by interview included lifetime occupational histories. A job exposure matrix was used to derive estimates of exposure for the 12 agents. ORs for ever versus never exposed and for exposure-response using duration of exposure and cumulative exposure were derived using conditional logistic regression stratified by sex, age group, country/region, adjusted for education.

Results: These analyses included 1906 cases and 5565 controls. For 11 of the 12 agents, no excess risk was found for ever exposed. For ever exposure to oil mists, an elevated OR of 1.57 (95% CI 1.10 to 2.22, 51 exposed cases) was found. Statistically significant exposure-response relationships were observed with cumulative exposure (p=0.01) and duration of exposure (p=0.04). Among women, there were also significant trends for cumulative and duration of exposure to asbestos and excesses in the highest exposure categories for formaldehyde.

Conclusions: Most agents examined did not provoke excess risks of meningioma. The main finding from this study is that it is the first study to identify a statistical association between exposure to oil mists and meningioma. This may be a chance finding or could be due to confounding with iron exposure and further research is required to understand whether the relationship is causal.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

In plain English

This international case-control study, part of the INTEROCC project, asked whether workplace exposure to 12 agents, including asbestos, was associated with meningioma, a brain tumour. It included 1906 people with meningioma and 5565 population controls from Australia, Canada, France, Germany, Israel, New Zealand and the UK, recruited from 2000 to 2004. Exposure was estimated from lifetime job histories using a job exposure matrix. The article does not name asbestos fiber types. Ever exposure to oil mist was associated with higher odds of meningioma (OR 1.57; 95% CI 1.10 to 2.22). After adjustment for iron exposure this fell to 1.38 (0.94 to 2.02). For asbestos, men and women combined showed no clear excess (OR 1.11; 0.90 to 1.37). Among women there was some evidence of a rising trend with duration of asbestos exposure (p=0.02) and with cumulative exposure (highest category OR 2.08; 1.00 to 4.34; p=0.03). This was not seen in men. The authors believed the asbestos finding in women to be a chance finding, given the number of statistical tests. They noted limited statistical power, particularly for women.

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: Multinational population-based case-control study (INTEROCC, formed from the INTERPHONE study), analysed with conditional logistic regression
• Who was studied: 1906 cases of primary meningioma and 5565 population controls, recruited from 11 study centres in Australia, Canada, France, Germany, Israel, New Zealand and the UK, 2000 to 2004; 73% of cases were female
• Exposure: Occupational exposure to 12 agents estimated with a job exposure matrix (INTEROCC JEM, based on the Finnish FINJEM). The agents were diesel and gasoline engine exhaust, bitumen fumes, benzo(a)pyrene, polycyclic aromatic hydrocarbons, asbestos (fiber type not specified; cumulative exposure in f/cm3-years), quartz, animal dust, wood dust, formaldehyde, oil mist and sulphur dioxide. Exposed meant at least 1 year in a job with an estimated exposure probability of 25% or more, with a 5-year lag.
• Main results:
  • Ever exposure to oil mist, men and women combined: OR 1.57 (95% CI 1.10 to 2.22)
  • Oil mist, men and women combined: risk increased with increasing duration of exposure (trend p=0.04)
  • After adjustment for iron, the oil mist OR for men and women combined was 1.38 (95% CI 0.94 to 2.02); the authors suggested the oil mist association may be confounded by iron exposure
  • Ever exposure to asbestos, men and women combined: 177 exposed cases and 592 exposed controls, OR 1.11 (95% CI 0.90 to 1.37)
  • Ever exposure to asbestos among women: OR 1.50 (95% CI 0.98 to 2.28), described as of borderline statistical significance
  • Women, duration of asbestos exposure: some evidence of an increasing trend (p=0.02); for 15+ years the OR was 8.17 (95% CI 0.95 to 70.08)
  • The 15+ years asbestos category among women contained 6 cases and 1 control
  • Women, cumulative asbestos exposure: significant trend (p=0.03); highest category (181.8+ f/cm3-years) OR 2.08 (95% CI 1.00 to 4.34)
  • No exposure-response for asbestos was seen in men
  • Formaldehyde, 15+ years of exposure among women: OR 1.99 (95% CI 1.16 to 3.40); no excess in men
• The authors' conclusion: The authors believed the asbestos exposure-response finding in women to be a chance finding, particularly in view of the number of significance tests carried out
• Limitations the authors state:
  • Statistical power to detect associations was limited for less common exposures, particularly for women
  • Possible bias in the recall of job histories
  • The job exposure matrix assigns one exposure estimate to every job with the same title across countries
  • Because the oil mist association is new and many statistical tests were done, the authors said it must be interpreted with caution and replicated
  • A 5-year lag was used although meningioma may have a latency of 20 years or more

Topics

Medical terms in this study, explained in our Lexicon: Case-Control Study, Occupational Exposure, Cumulative Exposure, Confounding.

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