Lifetime occupational exposure to metals and welding fumes, and risk of glioma: a 7-country population-based case\u2013control study

Marie‐Élise Parent ,Jérôme Lavoué,Geza Benke,Joachim Schüz,Hugues Richard,Maria Blettner,Laurel Kincl,Brigitte Schlehofer,Michelle C Turner,Sarah Fleming,Daniel Krewski,Klaus Schlaefer,Jordi Figuerola,Jack Siemiatycki,Martie Van Tongeren,Siegal Sadetzki,D J Mclean ,Lesley Richardson,Martine Hours,Elisabeth Cardis

doi:10.1186/s12940-017-0300-y

Abstract

BackgroundBrain tumor etiology is poorly understood. Based on their ability to pass through the blood–brain barrier, it has been hypothesized that exposure to metals may increase the risk of brain cancer. Results from the few epidemiological studies on this issue are limited and inconsistent.MethodsWe investigated the relationship between glioma risk and occupational exposure to five metals - lead, cadmium, nickel, chromium and iron- as well as to welding fumes, using data from the seven-country INTEROCC study. A total of 1800 incident glioma cases and 5160 controls aged 30–69 years were included in the analysis. Lifetime occupational exposure to the agents was assessed using the INTEROCC JEM, a modified version of the Finnish job exposure matrix FINJEM.ResultsIn general, cases had a slightly higher prevalence of exposure to the various metals and welding fumes than did controls, with the prevalence among ever exposed ranging between 1.7 and 2.2% for cadmium to 10.2 and 13.6% for iron among controls and cases, respectively. However, in multivariable logistic regression analyses, there was no association between ever exposure to any of the agents and risk of glioma with odds ratios (95% confidence intervals) ranging from 0.8 (0.7–1.0) for lead to 1.1 (0.7–1.6) for cadmium. Results were consistent across models considering cumulative exposure or duration, as well as in all sensitivity analyses conducted.ConclusionsFindings from this large-scale international study provide no evidence for an association between occupational exposure to any of the metals under scrutiny or welding fumes, and risk of glioma.

Highlights

We report on associations between glioma and occupational exposure to five metals- lead, cadmium, nickel, chromium and iron- as well as to welding fumes, using the INTEROCC data
Exposure prevalence ranged from 1.7–2.2% for cadmium up to 10.2–13.6% for iron among controls and cases, respectively
Once covariates were included in the models, there was no association between ever exposure to any of the agents and glioma risk, with odds ratios (OR) ranging from 0.8 for lead to 1.1 for cadmium

Summary

Introduction

Based on their ability to pass through the blood–brain barrier, it has been hypothesized that exposure to metals may increase the risk of brain cancer. Results from the few epidemiological studies on this issue are limited and inconsistent. The etiology of brain tumors is not well understood. Studies on possible risk factors for brain tumors have recently been reviewed [4]. Most studies show an increased risk of brain tumor after exposure to ionizing radiation. Based on positive associations between glioma and exposure to radiofrequency electromagnetic fields (RF-EMF) from wireless phones, RF-EMF have been classified as possibly carcinogenic [5]. Findings have been largely inconsistent [1,2,3,4, 6]

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