Cellphones affect human cells without heating them

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CELLPHONE makers take great care to ensure their gadgets don’t heat up your brain, but could the radiation cellphones throw out damage your cells in some other way?

CELLPHONE makers take great care to ensure their gadgets don’t 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.

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 – 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, DOI: 10.1042/BJ20061653).

The team is confident that the effect was not caused by heating: “The radiation that we used was very low-energy, and our sensitive thermostats did not register a change in the temperature of the cell medium,” says team member Rony Seger. “The significance lies in showing that cells do react to cellphone radiation in a non-thermal way.”

While mutations in ERK pathways have been linked to several cancers, experts caution that this is not necessarily evidence of a cancer-causing effect. “Transient and reversible activation such as this is unlikely to [cause cancer],” says Simon Arthur at the University of Dundee in the UK. In fact, he says, “transient 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“.

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. “If cellphone radiation cannot induce biological effects then there will never be any health effects,” he says. “On the other hand, if we can show that this radiation is able to induce biological effects then we have a different story. It doesn’t automatically mean that it will be harmful, but we will need to study it further.

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.

Caroline Williams

Issue 2619 of New Scientist magazine, 30 August 2007, pp 18.

Cellphones affect human cells without heating them

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