Occupational exposure to unintentionally emitted nanoscale particles and risk of cancer: From lung to central nervous system - Results from three French case-control studies

Our plain-English summary of Occupational exposure to unintentionally emitted nanoscale particles and risk of cancer: From lung to central nervous system - Results from three French case-control studies, by G. Manangama, C. Gramond, S. Audignon-Durand, et al (Environmental Research, 2020).

The study

• Authors: G. Manangama, C. Gramond, S. Audignon-Durand, I. Baldi, P. Fabro-Peray, A. Gilg Soit Ilg, P. Guénel, P. Lebailly, D. Luce, I. Stücker, P. Brochard, A. Lacourt
• Journal: Environmental Research
• Published: 2020;191:110024
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Nanoscale particles (1-100 nm) can be of natural origin, and either intentionally or unintentionally produced by human activities. Toxicological data have suggested a possible carcinogenic effect of such particles. The aim of this study was to estimate the association between occupational exposure to nanoscale particles and risk of lung cancer, pleural mesothelioma and brain tumors in adults.

Methods: Three French population-based case-control studies were analyzed: 1) the ICARE study including 2029 lung cancer cases and 2591 controls; 2) the PNSM study including 371 pleural mesothelioma cases and 730 controls and 3) the CERENAT study including 257 brain tumor cases and 511 controls. Occupational exposure to unintentionally emitted nanoscale particles (UNPs) was retrospectively assessed by a job exposure matrix providing a probability and a frequency of exposure.

Results: In adjusted analyses among men, significant associations between occupational exposure to UNPs and lung cancer (OR = 1.51; 95% CI: 1.22-1.86 and brain tumors (OR = 1.69; 95% CI: 1.17-2.44) were observed. No increased OR was observed for pleural mesothelioma (OR = 0.78; 95% CI: 0.46-1.33).

Conclusion: This is the first study showing positive associations between occupational exposure to UNPs and increased risk of lung cancer and brain tumors. These preliminary results should encourage further epidemiological research.

Copyright © 2020 Elsevier Inc. All rights reserved.

In plain English

This article analyzed three existing French population-based case-control studies. The authors asked whether exposure at work to unintentionally emitted nanoscale particles (UNPs: solid particles 1 to 100 nm, released by work processes involving high temperatures, combustion or high-energy mechanical work) was associated with lung cancer, pleural mesothelioma and brain (central nervous system) tumors. Exposure was estimated from job histories using a job-exposure matrix that gave a probability and a frequency of exposure, but not an intensity. The lung cancer analysis was adjusted for smoking, asbestos and silica. The mesothelioma analysis was adjusted for occupational asbestos exposure. Men classed as probably exposed, compared with unexposed men, had an odds ratio of 1.51 (95% CI 1.22–1.86) for lung cancer and 1.69 (95% CI 1.17–2.44) for brain tumors. For pleural mesothelioma the odds ratio was 0.78 (95% CI 0.46–1.33). No significant associations were found among women. The authors concluded this was the first study to show positive associations with lung cancer and brain tumors, and called the results preliminary. They said the lack of an intensity measure made dose-response estimates impossible.

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: Analysis of three population-based case-control studies (ICARE, PNSM, CERENAT), with occupational exposure assessed retrospectively by a job-exposure matrix
• Who was studied: Adults in France. The main analyses were in men: the ICARE lung cancer study (2029 cases, 2591 controls; 2001–2007, 10 departments), the PNSM pleural mesothelioma study (371 cases, 730 controls; 1998–2002, 19 departments) and the CERENAT brain tumor study (257 cases, 511 controls; 2004–2006, four departments). Women were analyzed separately.
• Exposure: Lifetime occupational exposure to unintentionally emitted nanoscale particles (solid particles 1–100 nm produced by human activities at work). It was assessed with the MatPUF job-exposure matrix, which gave probability and frequency of exposure but not intensity. Occupational asbestos exposure was treated as a confounder in the lung cancer and pleural mesothelioma analyses.
• Main results:
  • Lung cancer, men: probably exposed compared with never exposed, OR 1.51 (95% CI 1.22–1.86)
  • Lung cancer, men, by highest probability of exposure: OR 1.59 (95% CI 1.25–2.02) for probability between 50% and 90%, and OR 1.46 (95% CI 1.17–1.83) for probability above 90%
  • Lung cancer, men, among probably exposed subjects: OR per one-year increase in total weighted duration of exposure was 1.09 (95% CI 0.99–1.20), and 1.06 (95% CI 0.99–1.13) for unweighted duration
  • Pleural mesothelioma, men: probably exposed compared with non-exposed, adjusted OR 0.78 (95% CI 0.46–1.33)
  • All central nervous system tumors, men: probably exposed compared with non-exposed, OR 1.69 (95% CI 1.17–2.44)
  • Men, by tumor type: OR 2.19 (95% CI 0.96–5.01) for meningiomas and OR 1.47 (95% CI 0.91–2.36) for neuroepithelial tumors
  • Central nervous system tumors, men: no clear trend with probability of exposure or with duration of exposure
  • Women: no significant associations. ICARE OR 1.07 (95% CI 0.79–1.46); PNSM OR 1.89 (95% CI 0.93–3.85); CERENAT OR 0.78 (95% CI 0.54–1.13)
  • Lung cancer, men: it was unclear whether the size of the ORs was linked to a specific chemical family of particles or to a mixture of families
  • Central nervous system tumors: adjusting for pesticide exposure and mobile phone use gave ORs similar to those in the main analyses
• The authors' conclusion: The authors concluded that, to their knowledge, this was the first study to show positive associations between occupational exposure to UNPs and increased risk of lung cancer and central nervous system tumors. They described the results as preliminary, needing confirmation by analyses that include intensity of exposure. In the discussion they also wrote that the study allowed them to rule out an association with pleural mesothelioma.
• Limitations the authors state:
  • The job-exposure matrix had no intensity-of-exposure parameter, so dose-response relationships could not be estimated
  • Exposure to PM2.5 from outdoor air pollution could not be taken into account
  • The results in women may reflect the low number of female cases and the exposure assessment method, which may be less sensitive for women
  • Small sample sizes prevented analyses by chemical family for pleural mesothelioma and central nervous system tumors

Topics

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

Medical terms in this study, explained in our Lexicon: Occupational Exposure, Carcinogenic, Lung Cancer, Pleural Mesothelioma.

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