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2.Researchers conducted a large battery of laboratory tests to assess the effects of exposure to mobile phone RF on genetic material. These included tests for several kinds of ab- normalities, including mutations, chromosomal aberrations, DNA strand breaks, and structural chang- es in the genetic material of blood cells called lymphocytes. None of the tests showed any effect of the RF except for the micronucleus assay, which detects structural effects on the genetic material. The cells in this assay showed changes after expo- sure to simulated cell phone radia- tion, but only after 24 hours of expo- sure. It is possible that exposing the test cells to radiation for this long re- sulted in heating. Since this assay is known to be sensitive to heating, heat alone could have caused the ab- normalities to occur. The data al- ready in the literature on the re- sponse of the micronucleus assay to RF are conflicting. Thus follow-up re- search is necessary. 2

FDA is currently working with gov- ernment, industry, and academic groups to ensure the proper follow- up to these industry-funded research findings. Collaboration with the Cellular Telecommunications Industry Association (CTIA) in particular is expected to lead to FDA providing research recommendations and scientific oversight of new CTIA-funded research based on such recommen- dations.

Two other studies of interest have been reported recently in the litera- ture:

•Two groups of 18 people were ex- posed to simulated mobile phone signals under laboratory condi- tions while they performed cogni- tive function tests. There were no changes in the subjects' ability to recall words, numbers, or pic- tures, or in their spatial memory, but they were able to make choic- es more quickly in one visual test when they were exposed to simu- lated mobile phone signals. This was the only change noted among more than 20 variables com- pared.3

•In a study of 209 brain tumor cas- es and 425 matched controls, there was no increased risk of brain tumors associated with mo- bile phone use. When tumors did exist in certain locations, howev- er, they were more likely to be on the side of the head where the mobile phone was used. Because this occurred in only a small num- ber of cases, the increased likeli- hood was too small to be statistically significant.4

In summary, we do not have enough information at this point to assure the public that there are, or are not, any low incident health problems associated with use of mobile phones. FDA continues to work with all par- ties, including other federal agencies