Studies on short-term exposure to radio-frequency (RF) energy have shown little to no evidence that the levels used in cellular transmissions can lead to the development of cancer. Even at substantially higher levels, only a few laboratory tests have reported a possible correlation between cancer and RF safety levels in test animals, but these tests have failed with attempts at confirmation. Some of these studies have shown “clusters” of cancer cases in areas near cell towers. Critics counter that these cases are of many various kinds of cancer, and it is highly unlikely that they share a common cause. Further, with the sheer number of cell towers in use, statistics suggest that finding such clusters by chance is inevitable.
Many experts, including the American Cancer Society, say that there is little theoretical reason to believe that RF exposure can lead to cancer, and similar non-thermal effects. The concern is that since cell phones are a relatively new technology, not enough time has elapsed for long-term studies to show viable results. Several organizations have taken a cautionary stance on RF safety until long-term effects can be conclusively determined. The International Association of Fire Fighters (IAFF) adopted a resolution to oppose the installation of base station antennas on any Firehouses in 1994, citing several studies showing possible health risks from RF exposure. However, many of these studies were conducted at levels much higher than used in cellular transmissions, or otherwise focused on mobile and cordless phones themselves, not cellular base stations.
Following recent movements in various countries to enact recommendations about RF safety against excessive cell phone use by minors, many have also started to call against base stations being erected on top of schools. Often, their reasons are focused on potential risks of cell phone use, rather than those concerning the base stations themselves.
Multiple symptoms were reported up to 200 meters away, including nausea, irritability, and headaches, leading the authors to advise that “base stations should not be sited closer than 300 meters to populations.” However, many observers noted a strong likelihood of participation bias, as those responding to the survey announcements were likely already concerned about the impact of base stations on RF safety. Further, the questionnaire attempted to link distance from towers with exposure. According to the Journal of Exposure Analysis and Environmental Epidemiology, “It would be inappropriate to conduct epidemiological investigations based on proximity to mobile phone base stations since this exposure metric is a poor surrogate for an individual’s exposure to radio waves.”
To specifically address this issue, some studies attempt to replicate base station exposure in a lab environment. One such 2006 study subjected a total of 117 healthy subjects (33 who identified themselves as sensitive to RF radiation, and 84 who were non-sensitive) to Base Station-like exposure. The double-blind sessions were held at 1-week intervals, at the same time of day each session.
Most other commonly cited studies have focused on mobile phones themselves. While the results have been inconclusive and mixed, their significance to Base Station risks themselves is limited, as mobile phones produce a much more targeted radiation, which affect a specific portion of the body directly and at close range. Despite these differences, such studies are often held up as examples of research demonstrating possible health hazards from cell towers. Confusing the issue further are concerns centering on power lines and the magnetic fields they produce. Although some studies have suggested increased rates in childhood leukemia near power lines, the Electromagnetic Fields (or EMF) they produce work in fundamentally different ways from RF energy emitting sources, such as base stations, as they do not produce non-ionizing radiation, and do not continue to exist once the power is cut.
For the purpose of short-term exposure, the scientific community holds a consensus that the RF energy emitted by base stations is safe as long as it follows guidelines set by regulatory bodies, such as the FCC.