Analysis A study of 913 pregnant women in the San Francisco Bay Area, California, found those exposed to high levels of magnetic field (MF) non-ionizing radiation had a 2.72x higher risk of miscarriage than those exposed to low MF levels.

The Kaiser Permanente study, “Exposure to Magnetic Field Non-Ionizing Radiation and the Risk of Miscarriage: A Prospective Cohort Study,” was published this month in the journal Scientific Reports.

The authors, Kaiser researchers De-Kun Li, Hong Chen, Jeannette R. Ferber, Roxana Odouli, and Charles Quesenberry, say their findings add to the evidence that “MF non-ionizing radiation could have adverse biological impacts on human health.”

Mobile phones and Wi-Fi transmitters fire out radio-frequency MF radiation, but are not the only sources of such emissions; as such the study should not be construed as a specific indictment of those devices. Indeed, rather worry solely about smartphones or wireless networks peppering you with radiation, being surrounded by everyday electrical things – from fridges and freezers to hairdryers and clothes irons – may be more harmful than you may think. Possibly.

“In this study, we found an almost three-fold increased risk of miscarriage if a pregnant woman was exposed to higher MF levels compared to women with lower MF exposure,” the study says. “The association was independent of any specific MF exposure sources or locations, thus removing the concern that other factors connected to the sources of the exposure might account for the observed associations.”

Threshold

Study participants were classified in four MF exposure groups – <2.5mG; 2.5–3.6mG; 3.7–6.2mG; and ≥6.3mG – based on 24 hours of measurements with an EMDEX Lite meter as a representation of daily exposure. The researchers did not find the miscarriage risk increased with doses above 2.5mG, leading them to theorize that 2.5mG represents a threshold level for health effects.

In an email to The Register, Dr De-Kun Li, senior research scientist at the research division of Kaiser Permanente Northern California, said: “Please keep in mind that our study was not specifically designed to study radio-frequency magnetic fields, which are more applicable to cell phones and Wi-Fi. Also, we are at an early stage in understanding the health effects of magnetic fields; this is not a settled issue.”

Li said past studies of magnetic fields suffered from poor methods of measurement.

“The controversy over health effects from electromagnetic fields is, to a large extent, a product of earlier studies that did not find many associations between EMF and health risk,” he said. “Looking back, the main reason for the ‘negative findings’ is that those studies were not able to actually measure EMF exposure. When one can’t measure an exposure (e.g., EMF), the ‘study finding,’ by definition, won’t be able to find any association, thus negative findings. This applies to any study, not just those related to EMF. (For example, if one can’t measure the amount of calorie intake, one would conclude that calorie intake has nothing to do with being overweight.)”

Li said his group’s study supports the previously reported association between exposure to high MF levels in pregnancy and the risk of miscarriage, which has been suggested in at least seven other studies.

As Li observed, there is no scientific consensus that MF exposure harms human health. According to the National Cancer Institute, “[A]lthough many studies have examined the potential health effects of non-ionizing radiation from radar, microwave ovens, cell phones, and other sources, there is currently no consistent evidence that non-ionizing radiation increases cancer risk.”

The Kaiser researchers contend that the focus on studying the effect of MF radiation on cancer has made a more general focus on other health effects more difficult because the length of time required before cancer develops has led to inconclusive studies and has supported the impression that MF is entirely safe.