As the number of base stations and local wireless networks increases, so does the RF exposure of the population. WHO has noted in its fact sheet on base stations and wireless technologies that "Recent surveys have shown that the RF exposures from base stations range from 0.002% to 2% of the levels of international exposure guidelines, depending on a variety of factors such as the proximity to the antenna and the surrounding environment. This is lower or comparable to RF exposures from radio or television broadcast transmitters."
A common concern about base station relates to the possible long-term health effects that whole-body exposure to the RF signals may have. As per the WHO, to date, the only health effect from RF fields identified in scientific reviews has been related to an increase in body temperature (> 1 °C) from exposure at very high field intensity found only in certain industrial or professional applications, such as RF heaters. The levels of RF exposure from base stations and wireless networks are so low that the temperature increases are insignificant and do not affect human health.
The World Health Organisation's (WHO) fact sheet on base stations and wireless technologies discusses the scientific evidence for adverse health effects. It concludes that “there is no convincing scientific evidence that the weak RF (radio frequency) signals from base stations and wireless networks cause adverse health effects”.
WHO has also addressed concerns with regard to media or anecdotal reports of cancer clusters around mobile phone base stations that have heightened public concern. WHO has stated that "It should be noted that geographically, cancers are unevenly distributed among any population. Given the widespread presence of base stations in the environment, it is expected that possible cancer clusters will occur near base stations merely by chance. Moreover, the reported cancers in these clusters are often a collection of different types of cancer with no common characteristics and hence unlikely to have a common cause." WHO goes on to state that "Scientific evidence on the distribution of cancer in the population can be obtained through carefully planned and executed epidemiological studies. Over the past 15 years, studies examining a potential relationship between RF transmitters and cancer have been published. These studies have not provided evidence that RF exposure from the transmitters increases the risk of cancer. Likewise, long-term animal studies have not established an increased risk of cancer from exposure to RF fields, even at levels that are much higher than produced by base stations and wireless networks."
It is pertinent to note that the WHO's research agenda does not include further studies into the effects of RF exposure from base stations. WHO in its above fact sheet has stated "While no health effects are expected from exposure to RF fields from base stations and wireless networks, research is still being promoted by WHO to determine whether there are any health consequences from the higher RF exposures from mobile phones".