CELLPHONE makers take great care to ensure their gadgets don鈥檛 heat up your brain, but could the radiation cellphones throw out damage your cells in some other way? Israeli researchers have now identified a mechanism through which the radiation may affect the differentiation and division of cells.
Claims of connections between cellphone radiation exposure and health problems such as cancer have been controversial, largely due to a lack of convincing evidence, but also because no clear mechanism was known by which radiation at cellphone frequencies and power levels could harm living cells. The frequencies are too low to damage DNA directly and the power of the signal is well below the level that could overheat cells. Previous evidence of non-thermal effects on cells is mixed, because it is very difficult to expose cells to radiation without heating them to some degree.
鈥淭here had been no clear mechanism by which cellphone radiation and power levels could harm living cells鈥�
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In the new study, Joseph Friedman and colleagues at the Weizmann Institute of Science in Rehovot exposed rat and human cell cultures, and also isolated cell membranes, to low-level electromagnetic radiation at 875 megahertz 鈥� a similar frequency to those of GSM phone signals. The power of the signal was far lower than the intensity of the typical cellphone, yet after just 10 minutes of exposure, the team identified activation of the pathway for ERK1/2, an enzyme that regulates cell differentiation and division. The researchers then inhibited various stages in the pathway upstream of ERK1/2 and concluded that the molecular trigger for the enzyme is the release of reactive oxygen species in the cell membrane (Biochemical Journal, ).
The team is confident that the effect was not caused by heating: 鈥淭he radiation that we used was very low-energy, and our sensitive thermostats did not register a change in the temperature of the cell medium,鈥� says team member Rony Seger. 鈥淭he significance lies in showing that cells do react to cellphone radiation in a non-thermal way.鈥�
While mutations in ERK pathways have been linked to several cancers, experts caution that this is not necessarily evidence of a cancer-causing effect. 鈥淭ransient and reversible activation such as this is unlikely to [cause cancer],鈥� says Simon Arthur at the University of Dundee in the UK. In fact, he says, 鈥渢ransient activation of ERK1/2 occurs frequently in response to a huge variety of signals and is an essential component of many aspects of cellular physiology鈥�.
Dariusz Leszczynski of the Radiation and Nuclear Safety Authority in Helsinki, Finland, also cautions against making the leap between cells and health effects, but says they cannot be ruled out. 鈥淚f cellphone radiation cannot induce biological effects then there will never be any health effects,鈥� he says. 鈥淥n the other hand, if we can show that this radiation is able to induce biological effects then we have a different story. It doesn鈥檛 automatically mean that it will be harmful, but we will need to study it further.鈥�
In 2002, Leszczynski reported that cellphone radiation stimulated a stress-related pathway downstream of ERK1/2, but did not investigate what could be triggering it.
