Cell biologists are of two minds about the possible biological effects of mobile phone radiation. In the mid-1990s, studies describing possible pathological effects on tissues bombarded with low-level radio frequencies (RF) were first featured in the popular press and then discredited by scientists. Yet as mobile phone use rises worldwide among both adults and children, the possibility of unseen biological impact is quietly troubling.
“The available scientific evidence does not show that any health problems are associated with using wireless phones,” declares the US Food & Drug Administration’s web site (www.fda.gov/cellphones) but adds, “There is no proof, however, that wireless phones are absolutely safe.” The FDA clearly presents the scientific consensus; there is no significant epidemiological evidence of adverse health impact and most laboratory reports of biological impact are either unclear or disputed.
This consensus has its critics and Dariusz Leszczynski is one of the most prominent in Europe. Research Professor and Head of the Laboratory of Radiation Biology at STUK, Finland’s Radiation and Nuclear Safety Authority in Helsinki, Leszczynski believes that the “low sensitivity” of epidemiological studies may not be able to spot potential health hazards. Thus it falls on animal and in vitro studies, says Leszczynski, to convincingly answer the question of biological effect. “Mobile phone radiation must first be able to induce biological effects before it could have any impact on health,” he says. “Without biological effects, there will be no health effects. At the same time, we must keep in mind that the induction of biological effects does not automatically mean that there will be a health impact. For example, the biological effects might be too small to alter cell physiology—a prerequisite for any health impact.”
Still, Leszczynski reports additional evidence for biological effects from low-level RF exposure. Using high-throughput screening techniques such as transcriptomics and proteomics, he sifted through the genes and proteins expressed by human endothelial cells grown in culture at a constant temperature and subjected 900 or 1800 MHz frequency radiation used most commonly by GSM mobile phones. Working with his STUK colleague Reetta Nylund, Leszczynski identified an aberrant low-molecular weight form of vimentin, a developmentally regulated IF (intermediate filament) protein. Vimentin is an important component of the cytoskeleton, providing mechanical resistance to cells, and helping cells adhere to each other to form durable tissues. Flaws in cytoskeletal components can hamper vital cell functions.
Using cDNA arrays and HPLC/tandem mass spectrometry, the STUK lab also found changes in the expression of other cytoskeletal genes and proteins, including fascin, a-actinin-1, cofilin, destrin, filamin-A, and tubulin-?2. These results suggest that the cytoskeleton is the place to look for possible biological effects, according to Leszczynski. Meantime, he will continue using transcriptomics and proteomics to identify other potential molecular targets of mobile phone radiation.
This is not Leszczynski’s first challenge to the mobile phone consensus. In 2002, his lab challenged a key assumption about low-level RF and the expression of “heat shock proteins” (Hsp). His interest in Hsp proteins stemmed from the conventional reassurance that high-level RF is dangerous to cells because it heats them up (like a microwave oven), but low-level RF from cell phones is safe because it does not heat cells. Leszczynski wondered if low-level RF might stress cells into producing Hsp even without heating. Hsp proteins are a hot topic in cell biology because they are produced in response to many kinds of stress, for example helping cells defend against heat, osmotic stress, or oxidative damage. By carefully controlling the temperature of cultured human endothelial cells at 37 ± 0.3oC while bombarding them with a 900 MHz GSM-signal, Leszczynski saw an increase in the expression and phosphorylation of a stress response protein, Hsp27. The open question is whether or not such responses are sufficient for cells to cope.