Swinburne University of Technology - Melbourne Australia

Phone health an elusive call

Story by Bianca Nogrady

How do you look for a health effect when there is no scientific precedent, no obvious physiological or physical mechanism to explain it, and the effect is likely to be so small that you will need extremely sensitive testing processes? This is the challenge facing researchers at the Australian Centre for Radiofrequency Bioeffects Research (ACRBR), which is investigating whether mobile phones and base stations affect people's health.

Although there has been public concern and debate about mobile phone health risks, there is little scientific basis for this fear, according to centre director Professor Rodney Croft from Swinburne University of Technology. "One of the big difficulties is that physics doesn't provide a mechanism that explains how a mobile phone or base station could have an effect on a person," he says.

Therefore, in the absence of a clear starting point, ACRBR researchers have tried to cover every possible base, says Dr Vitas Anderson, Associate Professor of Bioelectromagnetices at Swinburne and associate investigator at the ACRBR. "You name it, just about every biological endpoint you can think of is being investigated with respect to radiofrequency (RF) exposures."

The ACRBR was created in 2003 as a National Health and Medical Research Council Centre of Excellence, bringing together scientists from Swinburne, RMIT University, Monash University, the Institute of Medical and Veterinary Sciences in Adelaide, Telstra and overseas affiliates. Dr Anderson says the ACRBR is unique in its multidisciplinary approach to RF/health questions.

"The ACRBR is pulling together a lot of different research strings," Dr Anderson says. "In terms of the breadth of the program there are not really any other centres like it around the world."

Telstra chief technology officer Dr Hugh Bradlow says the collaboration with Swinburne brings together "a range of different electromagnetic energy (EME) research expertise within this unique facility, where knowledge and learning can be shared.

"The research conducted at Swinburne will continue to provide scientifically measured information to inform regulators, policy makers and the community about an area of popular interest - EME from mobile phones and base stations."

One of the six research directors at the centre is Swinburne's Professor Andrew Wood, a physicist with a long-time interest in the biological effects of RF fields. One area he is investigating is spatial distributions of temperature in the brain from exposure to RF radiation, using a common dye called rhodamine B, which changes intensity with small increases in temperature. In animal models, the dye allows researchers to measure the energy deposited into tissue from RF fields and to look for any 'hot spots' in the brain.

The thermal effect of RF radiation is one of the few areas in mobile phone research that is reasonably well understood in the biological model. The problem is that these thermal effects have only been observed at high-intensity RF radiation exposures, in research settings. These exposures are orders of magnitude greater than humans would ever be exposed to from a mobile phone or base tower, so the challenge is to see whether there are still subtle effects from the level of RF radiation exposure we encounter daily.

"The body is able to regulate against changes in warmth and so the issue there is whether local heating, even if it might be quite small, might take the body beyond its normal range of being able to compensate," Professor Wood says.

In conjunction with this, the research group is using mathematical modelling to explore how RF radiation spreads through tissue, especially tissue that is extremely close to the source of the radiation. The wavelength for the average mobile phone is about 30 centimetres, so when a person's cheek is just a few centimetres from the antenna it can be difficult to predict the field pattern of the radiation and what sort of exposure is created.

He is also investigating the effects at the level of individual cells in the brain - in particular, an essential brain component called the blood-brain barrier, which protects the brain from unwanted substances in the blood, but still allows exchange of essential molecules. "We're looking at the effects of RF fields on permeability, on resistance and on the expression of proteins that might indicate that the blood-brain barrier is somehow under threat."

However, so far his research has not unearthed any clear cause for concern. "It is early days, but we haven't yet found anything that would dissuade us from using our mobile phones on a regular basis," Professor Wood says.

Effects on brain activity

The brain is an obvious focus for research into RF radiation. Professor Croft is also examining effects on the brain, but from a different perspective - that of brain activity. Earlier research had suggested that mobile phones altered the pattern of a particular frequency of brain electrical activity known as alpha, so Professor Croft and his team set out to reproduce this finding. They have published a study of 110 people showing an enhancement of alpha activity, particularly in the region of the brain closest to where the mobile phone is held. "It is the first strong demonstration that something is going on here," Professor Croft says. However, the effect is very small. "We're looking at an effect size of five per cent, which is a very small effect, considering that if you close your eyes you might have enhancement of alpha of about 30 per cent."

The other issue is that while an effect on alpha activity has been observed in this study, there is nothing to suggest that this change is negative, or even positive, with regards to health outcomes.

Looking for real health effects of mobile phone radiation requires two very different research approaches: one that tests for short-term effects on human subjects and another that watches for long-term effects of mobile phone use in the general population. Swinburne researchers are conducting several human trials - randomised, double-blind, crossover trials designed to be as rigorous as possible - looking for short-term effects.

It might seem unusual to be subjecting healthy humans to RF radiation, but Professor Croft reminds us that there is little evidence to suggest that this is dangerous. "Although the reason for getting into it in the first place is because the community is concerned about harm, as experimenters we have no reason to believe there is a benefit as opposed to harm, or harm as opposed to benefit."

And in contrast to animal studies, which sometimes expose the subjects to massive doses of RF radiation, all the research done on humans is within conservative safety standards.

The long-term studies avoid this problem altogether, and simply watch for effects among mobile phone users in the community, particularly among children and the elderly. One area of particular interest is cancer risk. "The three main things that people have looked at are acoustic neuroma, meningioma and glioma," Professor Croft says. However, these brain cancers are extremely rare, and to study these in the general population researchers would need an impossibly large cohort.

Instead, researchers use a case-control approach, where data from each person with a cancer is compared with data from a person of similar age, gender and other factors, but who does not have cancer and therefore serves as a control subject. Mobile phone use and RF exposure can then be compared between the two subjects.

One such study is a large multi-centred international one on mobile phone use and brain cancer, known as Interphone, in which Australia is a participant. However, so far studies such as Interphone have failed to find clear effects, although Professor Croft says there have been some small effects observed in sub-groups, for example people who have used mobile phones intensively for more than 10 years on the same side of their head.

Another difficulty with long-term studies into mobile phone radiation is that technology is rapidly evolving. The mobile phones being used by those subjects today are different to those they will use next year and in 10 years' time. Mobile phone technology may have transformed so radically it will be impossible to compare health data from the previous decade.

The transition from 2G to 3G mobile phones is an illustration of this, although Professor Croft says that at this stage, the feeling is there should not be a huge difference in terms of RF exposure. "Clearly, the less energy required to send information, the better for the phone carrier, so the newer phones tend to be designed with that in mind. They tend to use less power than older ones, so in general I would think there would be less chance of anything happening."

So with all this knowledge of how RF radiation might affect humans, have the experts been convinced one way or the other that mobile phone radiation poses any threat?

"Lots of effects have been investigated, but none, apart from thermal, have really been yet established," Dr Anderson says. But he is cautious about signing off on that. "Having said that, because of the ubiquity of exposure, with so many mobile phones out there and because it's a relatively new phenomenon, in order to be absolutely sure people are still carrying out research in this area," he says. "Because if there was some real impact, given the large extent of exposure it could have significant community effects."

Professor Croft agrees, saying the evidence is just not there to suggest a problem. "Given we don't see any dramatic increases in anything from cancer to impairments in cognitive function, if there's going to be an effect it's likely to be very small."

Phantom's calls help radiation research

A Swinburne laboratory is hardly the place you would expect to come across a phantom called Sam, much less one filled with 'goop'. But Sam has a special place at the Australian Centre for Radiofrequency Bioeffects Research (ACRBR).

SAM is in fact a Standard Anthropomorphic Mannequin - a dummy shaped like the upper body of a human (the phantom) and filled with fluid that simulates human tissue (the goop).

Researchers use SAM to measure and monitor the absorption of radiofrequency (RF) energy in humans. A mobile phone is attached to the mannequin's head, and a robotic probe can then be inserted into the fluid at any one of about 15,000 locations in SAM's body to see the impact of mobile phone radiation on different parts of the body.

SAM - or more specifically the robotic probe that does the measuring - is one of many highly sophisticated devices in the ACRBR laboratory, which is spread across two locations on the Swinburne University of Technology campus. The lab opened in July last year, in partnership with Telstra Corporation, and contains much of the equipment once housed in Telstra's original research lab in Melbourne.

Professor Andrew Wood says the laboratory represents a unique cooperative opportunity for Swinburne and Telstra, enabling them to continue research into the impact of RF radiation in humans.

A jewel in the crown of the lab is the anechoic, or echo-less, chamber, which - despite its name - is not for sound. "It's to do with electromagnetic energy," Professor Wood says. "It absorbs everything and doesn't let any of the energy out and also doesn't let in any energy from outside. We can do all sorts of things in there and it doesn't affect people's mobile phones, and nothing comes in that would affect measurements."

The lab also includes a 'Ferris wheel', but it is too small for humans to ride. This device, which Professor Wood says resembles the London Eye, is a way of exposing laboratory mice to carefully controlled levels of radiofrequency radiation to look for biological effects.

The ACRBR is hosting Science and Wireless 2008's 'Unplugged and uncertain?' conference, 12 to 13 November at Swinburne University of Technology. It aims to answer questions about mobile phones and Wi-Fi in schools, homes and workplaces, and their impact on health. See www.acrbr.org.au for more information.