Workpackage 3

Led by Michelle Turner, ISGlobal (former CREAL)
Collaborating institutions: UEF, FIOH

Background
There are a number of occupational exposures to electromagnetic fields across the frequency spectrum. In some occupations, exposures of workers may be orders of magnitude greater than those experienced in non-occupational settings.

Objectives
WP3 consists of two main tasks to conduct novel epidemiological research on the potential health effects of occupational RF and IF exposure.  The first task seeks to build upon the large, established INTEROCC study to examine associations between RF and IF exposure based on SEMs that will be derived in WP6 and risk of glioma and meningioma overall, as well as potential synergies with occupational chemical exposures. The second task seeks to conduct a register-based cohort study in Finland to examine the potential reproductive health effects of occupational IF among female cashiers and will serve as a pilot study for a potential future multinational study of cashiers.

Proposed work
The INTEROCC project is a large-scale multinational brain tumour case-control study, conducted in seven countries (Table 2) included in INTERPHONE. The objective of INTEROCC is to address outstanding questions concerning occupational agents in the disease. Estimates of chemical and ELF exposures were determined for INTEROCC participants, and a number of manuscripts are currently submitted or in preparation that focus on risk of brain tumours in relation to such exposures. However, while the occupational part of the INTERPHONE questionnaire included source based questions to identify subjects with likely substantial exposures to EMF, this work has not yet been exploited and exposure assessment in INTEROCC to date has been based solely on job titles (i.e. linking job titles to estimates of chemical and ELF exposure based on updates of existing JEMs), with the possibility of exposure misclassification since subjects with the same job title may actually have vastly different exposure characteristics. Further, epidemiological analyses in INTEROCC to date have focused almost exclusively on chemical and ELF exposure, and additional work to construct meaningful indices of exposure to both RF and IF is needed.

Task two will include women aged ≤40 years, who either worked as cashiers (about 10,000 «exposed» to IF fields), or have worked elsewhere in the same stores (about 10,000 “unexposed”) in Finland. With a follow-up of 6 years, the expected number of pregnancies in both groups of women is 6,000 and the expected number of miscarriages is about 600. Study subjects will be identified through registries of two nationwide companies in Finland. Employers will provide maker and model of the EAS devices used and distance between the worker and each device, and exposure will be estimated based on this information and previous measurements of IF from EAS devices. Data on working conditions relevant to reproductive health (shift-work, standing, etc.) will be collected from employers and pregnancy outcomes (miscarriages, congenital anomalies, newborn data) from registries maintained by the National Institute for Health and Welfare. Associations between pregnancy outcomes and estimated exposures will be investigated.