Appendix C: Consumer Update on Wireless Phones155of the studies can answer questions about long-termexposures, since the average period of phone use in thesestudies was around three years.11.What research is needed to decide whether RF exposurefrom wireless phones poses a health risk?A combination of laboratory studies and epidemiologicalstudies of people actually using wireless phones wouldprovide some of the data that are needed. Lifetime animalexposure studies could be completed in a few years.However, very large numbers of animals would be neededto provide reliable proof of a cancer promoting effect if oneexists. Epidemiological studies can provide data that isdirectly applicable to human populations, but 10 or moreyears follow-up may be needed to provide answers aboutsome health effects, such as cancer. This is because theinterval between the time of exposure to a cancer-causingagent and the time tumors develop - if they do - may bemany, many years. The interpretation of epidemiologicalstudies is hampered by difficulties in measuring actual RFexposure during day-to-day use of wireless phones. Manyfactors affect this measurement, such as the angle at whichthe phone is held, or which model of phone is used.12.Which other federal agencies have responsibilitiesrelated to potential RF health effects?
