A new study of exposure to non-ionising radiation in pregnant women found a significantly higher rate of miscarriage amongst those with higher exposures[i].
Magnetic field non-ionising radiation is produced when electrical devices are in use, and is generated by electrical appliances, power lines and transformers, wireless devices and wireless networks. Humans are widely exposed to this radiation due to the amount of electrical devices in use. This type of radiation is much lower in energy than ionising radiation. Ionising radiation includes gamma rays and X-rays, and the health effects of these high-energy types of radiation, such as radiation sickness and cancer, are well known. The evidence of health effects of non-ionising radiation in humans is limited.
In the study, 913 pregnant women wore a magnetic-field monitoring device and kept a log of their activities for 24 hours. They were also interviewed to determine how typical their activities were on the day they were monitored. The researchers controlled for other factors known to affect the likelihood of miscarriage. Among those who had a typical day on the study day , the rate of miscarriage among the quarter of women with the lowest exposures was 10.4 % and among the three-quarters of women with the highest exposures, 24.2 % miscarried. According to the researchers, the rate of miscarriage in the general population is between 10 and 15 %. The data suggests that there is a significant increase in risk in the women with the highest exposure compared to the women with the lowest exposure. The increased risk was consistently observed regardless of the source or location of the magnetic fields, and the association was stronger among women who had a typical day on the study day. There was no dose-response relationship above a particular amount of exposure, and the researchers hypothesise that this could be due to a threshold effect in which exposures at or above this level could lead to miscarriage.
Dr De-Kun Li, the lead author of the study, said, “The study provides evidence from a human population that magnetic field non-ionising radiation could have adverse biological impacts on human health” [ii]. A strength of the study is that the exposure was measured objectively, rather than relying on the participants’ past recall, as is done in many studies. One of the most challenging aspects of assessing the health impact of magnetic field exposure is the ability to measure exposure accurately and at the relevant time for disease to be caused (e.g. for long-latency cancers, exposure should be measured many years before cancer develops). A limitation of the study is that the participants were only followed for one day, and that it was not logistically feasible for their exposure to be monitored for the whole of their pregnancy.
In addition to this new study, several earlier studies have also suggested an increased risk of miscarriage associated with high magnetic field exposure during pregnancy. The researchers conclude that the potential health risks from magnetic field non-ionising radiation needs more research.
[i] Li, D.-K., Chen, H., Ferber, J. R., Odouli, R. & Quesenberry, C. Exposure to Magnetic Field Non-Ionizing Radiation and the Risk of Miscarriage: A Prospective Cohort Study. Scientific Reports 7, 17541 (2017). https://www.nature.com/articles/s41598-017-16623-8 (Accessed 14th December 2017)
[ii] Health risks linked to electromagnetic field exposure. Sciencedaily. 13 December 2017. https://www.sciencedaily.com/releases/2017/12/171213095534.htm (Accessed 14th December 2017)