The second volume of a report that detailed the history of technologies later found to be harmful has sparked discussion over the possibility that mobile phones have cancer-causing radiation.
The European Environment Agency's Late Lessons From Early Warnings was first published in 2001. The 750-page second edition, published in January, discusses an increased risk of some brain tumours associated with long-term mobile phone use. Among other topics in the report's 20 case studies were industrial mercury poisoning, fertility problems caused by pesticides and hormone-disrupting chemicals in common plastics.
The report also alleges that governments and the mobile phone industry have been slow to respond to the problem.
In 2011, the World Health Organisation's International Agency for Research on Cancer called cellular device radiation "possibly carcinogenic", or cancer causing. It is believed that the electromagnetic radiation (EMR) emitted by these devices may harm brain cells, upsetting sleep patterns and causing migraines, memory problems and even tumours.
Recently, local company New Star began selling cases for mobile devices that are said to protect users from EMR exposure. Made by Pong Research a US-based firm, the Pong cases feature a patented, ultra-thin, flexible printed circuit board antenna that is said to redirect and redistribute the waves - both cellular (such as 3G) and Wi-fi - to the back of the device, away from your head.
There are Pong cases for a wide range of smartphones and other devices. Pong claims the case has been proven in laboratory tests to reduce users' exposure to mobile phone radiation by up to 95 per cent, putting it below the limit set by the US Federal Communications Commission.
Many studies have been conducted on the short- and long-term effects of mobile phone radiation. One by Yale School of Medicine, published last year in Scientific Reports, found that in tests on mice, exposure to EMR during pregnancy affected the brain development of offspring, possibly leading to hyperactivity.
Another study, published in 2011 in JAMA, the journal of the American Medical Association, found that 50 minutes of mobile phone use was associated with increased brain glucose metabolism (a marker of brain activity) in the region closest to the phone antenna, but its significance is still unknown.
In fact, despite the studies, researchers have yet to determine a causal link between mobile device usage and cancer. Still, many experts agree that it is better to be safe than sorry.
Dr Andrew Tan, a specialist in nuclear medicine and consultant at Raffles Hospital in Singapore, says the risk of mobile phone EMR cannot be dismissed. "Mobile phones cannot be completely avoided, and the risk of use has to be balanced against practical realities," he says. "I would advise against ... prolonged use of mobile phones."
Tan cites the important and extensive Interphone study, published in the International Journal of Epidemiology in 2010, which investigated the possible carcinogenic effects of mobile phone radiation. About 5,000 patients with brain cancer (glioma and meningioma) were interviewed about their mobile phone usage. The conclusion was, there was no increased risk in those types of brain cancers with mobile phone use.
Heavy users (an averageof 30 minutes daily for 10 years) had an increased risk of such brain tumours of 10 per cent to 40 per cent more than people in general. However, this result was also inconclusive, since there was a high risk of recall bias and errors.
"It is mainly because of this study that the IACR classified mobile phone electromagnetic radiation as potentially cancer-causing, in which the risk is credible, but errors cannot be ruled out," says Tan.
What is definitely known of mobile devices is that they generate heat energy. Radiation from phones is similar to that created by microwave ovens, as opposed to the type of radiation that breaks down molecules.
"EMR has a very wide spectrum, ranging from low-frequency radio waves to high frequency gamma radiation," Tan says. "Human toxicity of radiation depends on the type and energy level. High-frequency ionising radiation, such as gamma or X-rays, can damage DNA molecules and cause direct damage, and low-frequency radiation such as radio waves is non-ionising.
"Mobile phone EMR is non-ionising radiation, but it has a heating effect. This is of a lower frequency than ultraviolet radiation."
Certainly, if the brain is exposed to heat for a long period of time, it might be damaged. But mobile phones are capable of heating up the skin only superficially.
"It's very unlikely that your phone might raise the temperature of your brain and cause cancer," says Dr Clarence Leung Hin-shuen, honorary consultant and specialist in neurosurgery at Matilda International Hospital.
"Mobile phone use is potentially toxic, but there is no direct or adequate evidence to say that it is toxic. People worry about tumours along the auditory nerves and brain tumours, but there is no correlation between these and mobile phone use. These cellular devices have only been around for 15 years, so it might still be too early to reach any conclusion."
It is also hard to say whether certain types of mobile phones are more dangerous than others. Some might have higher energy emissions, so it's best to consult the manufacturer's specifications.
There is no need to worry about the radiation from other people's devices affecting you, says Leung. As long as you are standing a few inches away from people while they are using their devices, the radiation intensity you are exposed to is very low, since radiation energy drops very rapidly with distance.
There are many anti-radiation mobile phone products out there. According to Pong, what makes their case different is that it redistributes, rather than reduces, radiation. This also makes more radiation available for communication, resulting in a stronger signal and longer battery life.
The company says other products that claim to reduce radiation exposure by shielding, blocking, absorbing or neutralising mobile phone radiation either aren't effective or can actually increase exposure. Such products tend to weaken the signal, forcing the device to work harder and use more power.
Limiting mobile phone use is another way to minimise exposure to EMR. Leung suggests using a land-line phone or hands-free accessories, or putting your calls on speaker. Take note: Bluetooth headsets are still a source of radiation, albeit a small one.
Dr Ronald Herberman, director of the University of Pittsburgh Cancer Institute, offers other precautionary tips. One is to keep your mobile phone away from your body as much as possible. Avoid placing it under your pillow or on your bedside table when you go to sleep. If using the alarm function, switch to flight mode to stop the electromagnetic emissions. And if you carry your phone in a pocket, position the screen towards your body, as the antenna is located on the back.
He also suggests that when you talk on the phone, switch sides regularly to avoid overexposure on one side. Finally, wait until a call has been connected before placing your phone to your ear, because it emits the most radiation during the initial connection.