[Two of the authors respond:]
Ronald Cridland is correct in stating that we did not measure health in our study of radiofrequency emissions at several Vancouver schools. [1] However, our conclusion that there is no apparent risk to human health remains valid. It is based on the fact that the measured radiofrequency power densities were thousands of times below the Safety Code 6 limits, which incorporate a 50-fold safety factor from the scientifically established thresholds for harmful effects. Although we acknowledge that there is a body of evidence of biological effects at levels near or slightly below the Safety Code 6 limits, the evidence of adverse health effects at these intensities is weak. If one then considers the low probability of adverse health effects occurring at radiofrequency radiation levels thousands of times below the limits its in Safety Code 6 and other international standards (as were measured in the schools), then our conclusion seems justified.
To clarify another point, we made no attempt in this study to compare the measured levels of radiofrequency radiation to background radiation levels. Although it is true that the radiofrequency radiation levels measured in our study are much higher than naturally occurring (background) levels, this is necessary to make a radio system function properly.
Finally, with reference to Cridland's last remark, it has been known for some time that the physical properties and effects of x-radiation and radiofrequency radiation on matter are vastly different. As Cridland implies, ionizing radiation (x-rays) at low intensities possess sufficient energy to directly break chemical bonds in material such as DNA. This is not the case with the radiofrequency radiation investigated in this study, which possesses a photon energy at least 6 orders of magnitude lower than that of x-rays.
Artnarong Thansandote, PhD
Gregory B. Gajda, MASc
Radiation Protection Bureau; Health Canada; Ottawa, Ont.
References
- 1.↵