Mobile phone and cancer link
While a new study from Europe indicates that analogue phones increase the risk of brain tumours, Australian researchers show how this effect may occur.
Suggestions that mobile phones cause brain cancer have been touted now for nearly a decade. The issue was catapulted to public attention in 1993 when heavy mobile phone user, Suzie Reynard, died from a tumour she claimed was caused by her mobile phone and which was adjacent to the position of her phone antenna. Her husband commenced legal action. Though the action did not proceed, it generated a huge response from the media and the Wall Street market and encouraged mobile phone companies to instigate the Wireless Technology Research program that was run by Dr George Carlo. Since that time many other people have claimed that their brain cancers were caused by the use of their mobile phones and litigation on this issue is now proceeding in the US.
Until recently, research on the connection between brain cancers and mobile phone use has failed to yield results and studies showing no connection have been proudly flagged by industry as an affirmation that their products do not pose a risk. However, because mobile phone technology is a fairly recent development and brain cancers take many years to develop, it is not surprising that many studies have not observed an association.Analogue phones a brain cancer risk
This makes the latest study by Dr Lennart Hardell and Dr Kjell Johannsen Mild particularly important. The Swedish researchers have reported an increase in the incidence of brain cancer among users of the older style mobile phones.
Hardell and Mild conducted a survey of 1429 patients with brain tumours aged between 20 and 80 and an equal number of controls with no symptoms. They found that people who used analogue phones had a 26% greater chance of developing brain cancer and that this risk rose to 77% among people who had used them for more than ten years. They found that there was a greater likelihood of the tumour occurring on the side of the head on which the phone was held and that the most common type of tumour was the acoustic neurinoma.
The researchers did not find an increased risk of brain tumours among users of digital or cordless mobile phones. However, that does not exonerate these phones. Whereas analogue phones have been used in Sweden for around 15 years, digital phones have been used only for about four. As the researchers commented, a much longer latency period will be needed to see whether the effect is true for digital mobile phone use.
Meanwhile, there is evidence that the pulsed radiation from the digital system is even more biologically active that the radiation from analogue phones.Mobile phones, heat shock proteins and cancer
In a recent paper with the above title, an Australian team, led by Dr Peter French, presented their explanation as to how mobile phones can contribute to cancer.
The radiation from mobile phones is unquestionably non-thermal, as the body does not absorb enough radiation to cause significant heating. Studies have calculated that the maximum average amount of radiation absorbed or specific absorption rate(SAR) is around 1.6 W/kg and the maximum temperature rise in brain temperature is just 0.11°C. Nevertheless, there is evidence that this radiation is “not physiologically inert”. It has been linked with uveal melanomas, microwave hearing, changes to EEG patterns and changes to resting blood pressure. French and team suggest that these effects may be caused by heat shock proteins (HSPs).
According to the researchers, the HSP response is “present in all organisms from bacteria to plants and animals and functions as an essential mechanism for the protection of cells to a wide range of harmful stresses”. These include stresses other than heat. HSPs serve to refold or eliminate proteins that have become inappropriately folded by a stressor and “play a critical role in the regulation of the cell cycle, cell proliferation, differentiation and apoptosis.” Many tumours have been found to have altered expression of HSPs and the greater the expression of HSPs, the less likely is the cancer patient to survive free of the disease.
Several HSPs have been shown to have particular relevance for cancer. HSP 70 “can initiate cancer in normal cells” and seems to play a role in protecting cancer cells from death. Similarly, there is evidence that HSP 27 is associated with the invasiveness of cancer cells. Both these HSPs increase the resilience of cancer cells to anti-cancer treatments.
There is evidence that radiation from mobile phones produces HSPs at nonthermal levels of exposure. De Pomerai et al found that exposure at 750 MHz induced an HSP response in nematode worms at an SAR of 0.001 W/kg which “is 100-1000 times less than that reported for mobile phones.” French’s team has also shown that chronic nonthermal exposure to pulsed RF waves induces HSPs.
In conclusion the researchers write, “From published research on overexpression of HSPs, we postulate that potential outcomes could be the induction of oncogenesis or the promotion of metastatic cancer and/or induction of anti-cancer drug resistance. It is therefore critical that the hypothesis that RF energy at mobile phone-relevant SAR levels acts as a cell stress on human brain cells and tissues is tested experimentally as a potential mechanism for cancer development.”
(Hardell, L., presentation at “Mobile Telephones and Health”, Lond, June 6-7, 2001; French, PW et al, Differentiation, 67:93-97, 2001.)
EMRAA News Sept 2001, Vol 6 No 3