Cell phones have been linked to brain tumors and other health dangers in recent years, and now a team of researchers from Finland has used proteomics methods to suggest that they can alter protein expression in human skin.
In a study published Feb. 11 in the online edition of BMC Genomics, the researchers say that they have shown for the first time that radiation emitted from cell phones causes changes in humans on a molecular level, adding a new layer to the debate over cell phone safety.
However, the researchers are careful not to ascribe any health risks to their results. Dariusz Leszczynski, the lead author and a research professor at the Radiation and Nuclear Safety Authority in Finland, told ProteoMonitor that “it is not possible to say whether these changes might have any health implications” and at this stage, their work “shows only that mobile phone radiation, even very low energy radiation, is recognized by cells in the living tissue and triggers some response.”
Indeed, the team stressed that cell-phone radiation may alter protein expression in human skin, but the physiological significance of such changes is unknown and requires further study. Larger studies are required, as well, to confirm the results of their findings.
Cell Phones, Cell Changes
The researchers had earlier done several studies describing changes in protein expression and phosphorylation in human endothelial cell line EA.hy926 after being exposed to radiofrequency modulated electromagnetic fields, or radiation caused by cell phones.
Those studies, however, were performed in vitro, and the results “do not automatically mean that similar changes would happen in the cells of mobile phone users,” they say in their study.
For the BMC Genomics article, they performed an in vivo study aimed at determining whether protein expression in human skin that had been exposed to RF-EMF would undergo any changes, and whether there were any proteins which unilaterally changed across all test subjects.
The researchers looked at 10 volunteers, all women ages 27 to 65 with a median age of 51. The volunteers had a small skin area in one forearm exposed to radiation of 900 megaherz Global System for Mobile communications cellular network at an absorption rate of 1.3 watts per kilogram. According to Leszczynski, the level of radiation exposure is similar to that from a regular cell phone during a one-hour conversation.
Immediately after exposure, each volunteer had her skin biopsied: Both the dermis and epidermis from the exposed forearm was frozen in liquid nitrogen after being harvested and stored at minus-80 degrees Celsius. Tissue samples were taken from both the exposed skin area and from the non-exposed forearm.
Proteins from the skin were extracted using the TRIzol reagent from Invitrogen, and then separated by standard 2D gel electrophoresis with a pH gradient range of 4 to 7 in the first dimension and 9 percent SDS-PAGE gel in the second dimension.
Proteins were then detected by silver staining. PDQuest 7.2 software from Bio-Rad Laboratories was used for spot distribution pattern analysis.
Only proteins with an isoelectric point between 4 and 7 and a molecular weight of less than 40 kiloDaltons were analyzed, because the protein spot separation in 2D gel electrophoresis in this area “was clearly distinguishable,” the authors say in the study.
“It is not possible to say whether these changes might have any health implications” and at this stage, their work “shows only that mobile phone radiation, even very low energy radiation, is recognized by cells in the living tissue and triggers some response.”
Protein expression profiles for samples from the exposed areas and non-exposed areas were combined to generate an artificial gel using PDQuest software. The 10 artificial gels were then combined into an artificial master gel and the differentially expressed protein spots, detected in at least four volunteers, were statistically analyzed.
The researchers were able to identify a total of 579 protein spots. Of that, eight were differentially expressed where the change was statistically significant, including two that were present in all 10 volunteers.
The latter finding, Leszczynski said, “suggests that there might exist proteins that will be affected in all exposed persons — if so, these proteins could be used in tests as markers of exposure.”
He and his co-authors conclude that cell-phone radiation may alter protein expression in human skin, but the physiological significance of such changes requires further study. Larger studies are required, as well, to confirm the results of their findings.
Proteomics screening is a valid method for investigating molecular changes due to cell-phone radiation, they say and “without this approach, the identification of the proteins responding to mobile phone radiation would not be reasonably possible.”
In anticipated follow-up work, Leszczynski said he and his colleagues plan to identify the eight differentially expressed proteins, which they could not do for the current study due to a combination of “technical problems, and the small amount of proteins available in this study.”
When that is accomplished, they will be able to determine their functions. The follow-up study will increase the number of test cases to between 50 and 100 volunteers, Leszczynski said, and use a DIGE based approach with fluorescently labeled proteins.
“This will give us more reliable comparisons [between proteins that have been exposed to radiation and those that have not] and greater sensitivity,” he said. Proteins will then be identified by MALDI-TOF mass spectrometry and possibly tandem-mass spectrometry.
The researchers will then be able to determine whether the changes in protein expression are “of significant magnitude to alter the physiology of the exposed tissue,” Leszczynski said. “If no, then there will be no health problem. If yes, then there might be some concern.”
Can You Hear Me Now?
The findings come amidst an exponential growth in cell phone usage. The number of Americans who subscribed to cell phone service grew to more than 243 million in 2007, more than double the 97 million that subscribed in 2000, according to CTIA-The Wireless Association, an industry trade group.
While most users pay little mind to the purported health risks of cell-phone radiation, some studies suggest a link between cell-phone usage and cancer.
In an often-cited report published in the fall in Occupational Environmental Medicine, researchers concluded that while cell-phone usage appeared not to increase the risk of cancer during the first decade of usage, beyond that, there was a “consistent pattern of increased risk for acoustic neuroma [tumors of the nerve] and glioma [a central nervous system tumor arising from glial cells]. The risk is highest for ipsilateral exposure.”
The body of scientific research on the subject, however, is inconclusive at best. On its website, the US Food and Drug Administration says that “available scientific evidence does not show that any health problems are associated with using wireless phones. There is no proof, however, that wireless phones are absolutely safe.”
The agency further says that many studies of low-level radiofrequency exposure have found no biological effects. While some research has suggested that such exposure may lead to biological changes, those findings have not been confirmed by additional research, according to the FDA.
According to Leszczynski, results of in vitro studies, including his team’s earlier work, have detected biological changes on the protein level, and other studies have suggested that rats and mice that have been exposed to cell-phone radiation have a higher risk for cancer. However, making any assumptions about the health implications to humans based on such studies, would be premature, he said.
“What we are doing is very basic. We are trying to find out which molecules inside the body react to this radiation,” he said. “Then the next step will be to find out what processes are regulated by those molecules. And then only if those processes are being altered by radiation, only then could we can start to think, could it be harmful or not to our health,” he said.