5G is harmless unless you believe it isn't - doctor

People only report headaches, sleep problems and anxiety from cellphone towers if they already believe they're harmful, a Kiwi researcher has claimed.

Those who don't believe radio frequencies (RF) from cellphone towers are a hazard, or do but are unaware they're being exposed, don't report ill-effects, a wide-ranging look at previous studies has found.

University of Auckland epidemiologist Mark Elwood examined 29 studies into people who claim to be hyper-sensitive to RF. The vast majority found no links between RF and ailments such as headaches, anxiety, fatigue, dizziness and sleep problems, and those that did were of poor quality, according to an editorial published in the New Zealand Medical Journal on Friday. 

"Assessments of short-term effects under experimental conditions, where sham exposures are used as well as actual RF exposures, and subjects can be kept unaware of their real exposure, have shown no associations with symptoms," he wrote.

"This strongly suggests that associations with symptoms are not due to actual RF exposure. They may be due to other aspects of cell phone usage, such as time spent on calls, texting or games, or the psychological factors associated with this media use. 

"They may also be due to perceived RF exposure, where this perceived exposure is seen as detrimental to health, through a nocebo effect. That is due to the individual's negative expectations about getting symptoms or health effects following exposure, but not actual RF exposure."

The 'nocebo' effect is like the placebo effect, where a medically useless medicine works simply because someone believes it will. Except, in this case, people report symptoms when they think they're being exposed to RF, even if they aren't. 

"The best available scientific evidence does not support the concept that exposures to radiofrequency fields or other electromagnetic fields, from cell phones, base stations and other sources, cause increases in disease or increases in symptoms," Dr Elwood wrote.

"Despite this many people assume there are such effects. Some people believe that they are particularly susceptible or hypersensitive to radio frequencies and therefore suffer these effects."

One study he looked at found people were more likely to report ill-effects from RF exposure after watching a television documentary which proposed such effects were possible.

"The general issue is that the stories of ill-effects, and the studies showing ill-effects even if they are of very low quality, tend to receive the greatest attention."

False claims about RF, particularly cellphone technology like 4G and 5G, have become increasingly mainstream in recent years thanks to social media. 

"Irrespective of their causation, the symptoms experienced are real and affected individuals may have substantial ill-health and need appropriate supportive management," wrote Dr Elwood.

"Public perceptions of a potential hazard are affected by the information given, and encouraging better understanding of relevant science is important in this as in many other health issues."