Authored By:
Smith-Roe et al.This study, by Smith-Roe et al, is part of the National Toxicology Program’s (NTP) investigation of the effects radio waves, also called radiofrequency electromagnetic fields, have on rats and mice. This study examined possible genotoxic effects on a separate sample of rats and mice that were exposed for a shorter time period as part of the NTP study. The animals were exposed to radio waves at certain frequencies used by mobile phone networks (CDMA or GSM) for 9 hours a day at levels of up to 10 watts per kilogram (W/kg) over a period of up to 19 weeks. The study specifically reported on DNA damage within the tissues of the animals examined. The authors reported a statistically significant increase in levels of DNA damage in the frontal cortex of male rats and mice and in the hippocampus of male rats. Only the CDMA-modulated exposed rats had statistically significant levels of DNA damage for both tissue regions. Further, the study concluded there was variable levels of DNA damage observed. Overall, for female rats and mice, the study did not report any consistent statistically significant results.
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National Center for Biotechnology Information 2019In 2018, the NTP released their final reports, which investigated whether exposure to radio waves causes any health effects, including cancer, in rats and mice. An assessment of the results from the NTP study reports in their entirety have previously been provided by ARPANSA and the International Commission on Non-ionizing Radiation Protection (ICNIRP).
The study by Smith-Roe et al reports certain genotoxic effects related to radio waves at very high exposure levels, however the effects were inconsistent across rats and mice, males and females, and type of radio wave exposure (GSM or CDMA). There is no explanation for these variations in the results across species, gender and type of radio waves.
It is possible that that the reported effects occurred due to the high exposure levels. It is known that exposure to sufficiently high level radio waves can heat biological tissue and potentially cause tissue damage. It is also possible that the reported effects occurred due to chance. This is because the study conducted a number of different tests and, statistically, a positive result is always possible with multiple tests. This is often called the multiple comparisons or multiple testing problem.
In Australia, the safety standard for radio waves developed by ARPANSA sets mobile phone limits at 0.08W/kg for whole body and 2 W/kg for localised exposure. Most mobile phones produce exposures well below the limit. This makes it difficult to relate the high radio wave exposures of the animals in this study to the much lower exposure when people are using mobile phones. There have been many proposals for how radio waves, below the current exposure limits, could induce DNA damage in cells, however, there remains no proven mechanism for this effect or consistent results to confirm that it occurs. Overall, the study by Smith-Roe et al does not demonstrate consistent DNA damage across species, genders, or for types of radio waves and this could indicate that there is no common mechanism causing DNA damage (Fedak, 2015).
ARPANSA‘s safety standard is based on scientific research that shows the levels at which harmful effects occur and it sets limits, based on international guidelines, well below these harmful levels to provide a high level of protection to the public. Overall, the limitations in the results by Smith-Roe et al do not provide sufficient evidence to justify a change in the current safety limits for radio wave exposures set within the standard.
