Built upon the platform of the INTERPHONE study, the largest international collaborative case-control study of brain tumours yet conducted (Cardis et al 2007), the INTEROCC study is a collaboration between seven countries (Australia, Canada, France, Germany, Israel, New Zealand and the UK) that collected detailed lifetime job histories from study subjects. It has three specific aims:

1. To evaluate the possible association between occupational exposure to EMF and tumors of the brain and central nervous system (specifically, glioma and meningioma).
2. To evaluate the possible association between selected occupational chemical exposures and tumors of the brain and central nervous system (specifically, glioma and meningioma).
3. To investigate the possibility of synergism and/or confounding between chemical and EMF exposures on the risk of brain cancers.

To achieve these aims, each job held by subjects was coded according to international occupation and industry classifications: the International Standard Classification of Occupations editions 1968 (ISCO68) and 1988 (ISCO88), and the International Standard Industrial Classification of All Economic Activities, revision 2 (ISIC71). Common coding guidelines were provided to each center in order to ensure homogeneity in the coding. An inter-rater trial was conducted at the start of coding and results were discussed with each center in a further effort to ensure consistency of coding.

Occupational exposures to EMF (both ELF and RF/MW) and selected chemicals were assessed for all the study subjects using validated job-exposure matrices, which were developed within this project. The assessment of EMF exposure is also being refined as part of the GERoNiMO project by consolidating information obtained from the JEM with data on exposure variations related to the specific industry in which a subject worked, to the tasks he or she performed and to the actual sources of exposure, available from the INTERPHONE questionnaire.

For chemicals, the JEM based estimates were compared to estimates derived by occupational hygienists using the more detailed occupational histories in Canada, France, New Zealand and the UK, thereby providing an indication of the validity of the classification.

Analyses of the relationship between brain tumor risk and exposure to EMF and to the chemicals of interest are being carried out. Several scientific papers have been published and others are in preparation. Further analyses of possible interactions between EMF and specific chemicals will also be conducted.

Funding sources

US National Institute for Health R01 grant (R01CA124759)

Funding for improvement of the EMF exposure assessment and for further analyses is provided by the European Union in the framework of the GERoNiMO project  (EU grant agreement 603794)

Lacourt A, Cardis E, Pintos J, Richardson L, Kincl L, Benke G, Fleming S, Hours M, Krewski D, McLean D, Parent ME, Sadetzki S, Schlaefer K, Schlehofer B, Lavoue J, van Tongeren M, Siemiatycki. INTEROCC case-control study: lack of association between glioma tumors and occupational exposure to selected combustion products, dusts and other chemical agents. BMC Public Health 2013;13:340.

Lavoué J, Pintos J, van Tongeren M, Kincl L, Richardson L, Kauppinen T, Cardis E, Siemiatycki J. Comparison of exposure estimates in the Finnish job-exposure matrix FINJEM with a JEM derived from expert assessments performed in Montreal. Occup Environ Med 2012;69:465-471.

McLean D, Fleming S, Turner MC, Kincl L, Richardson L, Benke G, Schlehofer B, Schlaefer K, Parent ME, Hours M, Krewski D, van Tongeren M, Sadetzki S, Siemiatycki J, Cardis E.  2014. Occupational solvent exposure and risk of meningiona.  Results from the INTEROCC multi-centre case-control study. Occup Environ Med, in press.

Turner MC, Benke G, Bowman JD, Figuerola J, Fleming S, Hours M, Kincl L, Krewski D, McLean D, Parent ME, Richardson L, Sadetzki S, Schlaefer K, Schlehofer B, Schuz J, Siemiatycki J, van Tongeren M, Cardis E. 2014. Occupational exposure to extremely low frequency magnetic fields and brain tumor risks in the INTEROCC study.  Submitted.

van Tongeren M, Kincl L, Richardson L, Benke G, Figuerola J, Kauppinen T, Lakhani R, Lavoue J, McLean D, Plato N, Cardis E, for the INETEROCC study group. Assessing occupational exposure to chemicals in an international study of brain tumors. Ann Occup Hyg 2013;57:610-26.