Occupational exposure to electromagnetic fields and brain tumor development

With the technological advance in the field of communication which has occurred in the last decades, concerns have arisen regarding the possible health effects of public exposure to non-ionizing radiation (such as that emitted from cellphones, tablets, Wi-Fi etc.). Today the main public discussion focuses on evaluating the association between radiation exposure and cancer development. Based on population studies and studies in animals, the International Agency for Research on Cancer (IARC) determined that limited evidence exists for increase in risk of developing malignant brain tumors (glioma) and benign acoustic neuromas amongst people using cellphones. Accordingly, in 2011 the World Health Organization classified RF electromagnetic fields a possible carcinogen to humans. Regarding occupational exposure, the scientific knowledge from recent years is minimal and epidemiological evidence for the association between occupational exposure to RF-EMF and cancer is insufficient to draw conclusions, particularly due to limitations in exposure assessment.

In July 2018 a scientific article was published evaluating the possible association between occupational exposure to electromagnetic fields and brain tumor development. The article addresses intermediate frequency (IF) non-ionizing radiation, defined as the range between 3 KHz and 10 MHz and radiofrequency (RF) radiation defined as between 10 MHz and 300 GHz. The article was published by researchers from the INTEROCC research group comprising data from 7 of the 13 countries included in the INTERPHONE international case-control study which evaluated a possible association between cellphone use and the development of brain tumors (meningioma and glioma), acoustic neuromas and salivary gland tumors.

The INTEROCC study, the largest of its type in the world, was based on personal interviews about occupational history and included 3,978 brain tumor patients (2,054 malignant gliomas, 1,924 benign meningiomas) and 5,601 healthy people who served as a control group. The occupational questionnaire included questions about jobs title, workplaces or proximity to the following sources: radars, communication antennaes, transmitters, production of semiconductors materials, medical diagnosis and treatment, industrial heating and food heating.

For each participant in the study, a special index was developed aiming to evaluate his/her overall occupational exposure to RF and IF radiation, based on their occupational history. The development of a method of personal radiation exposure assessment is a major improvement in estimating exposure compared to what was standard in the past and constitutes an advantage of this study.

It is important to note that this study had several limitations:

• Only 10% of the participants were exposed to RF and only 1% to IF radiation at their workplaces. Even in this large study, the number of people exposed to the factor under investigation was small, limiting the statistical power to detect an association, if it exists.
• The index for exposure assessment was not based on personal RF measurements. It is possible that for some of the sources of exposure, the index presented under- or over –estimation of exposure of the head area. These points may affect the evaluation of brain tumor risk.
• As in all studies based on self-reporting of exposure history, there is recall bias which may be greater amongst brain tumor patients.
• Compliance rates were low, especially among the control group and may have influenced the observed risk.

References:

• Vila J; Turner  M. C; Gracia-Lavedan E et al. Occupational exposure to high-frequency electromagnetic fields and brain tumor risk in the INTEROCC study: An individualized assessment approach. Environment international 2018; 119; 353-365.

Updated: 21.10.2018