Section 4A: Safety Guidelines 174What are the results of the research done already?The research done thus far has produced conflicting results, and many studieshave suffered from flaws in their research methods. Animal experimentsinvestigating the effects of radiofrequency energy (RF) exposures characteristicof wireless phones have yielded conflicting results that often cannot berepeated in other laboratories. A few animal studies, however, have suggestedthat low levels of RF could accelerate the development of cancer in laboratoryanimals. However, many of the studies that showed increased tumordevelopment used animals that had been genetically engineered or treated withcancer-causing chemicals so as to be pre-disposed to develop cancer in theabsence of RF exposure. Other studies exposed the animals to RF for up to 22hours per day. These conditions are not similar to the conditions under whichpeople use wireless phones, so we don't know with certainty what the resultsof such studies mean for human health.Three large epidemiology studies have been published since December 2000.Between them, the studies investigated any possible association between theuse of wireless phones and primary brain cancer, glioma, meningioma, oracoustic neuroma, tumors of the brain or salivary gland, leukemia, or othercancers. None of the studies demonstrated the existence of any harmful healtheffects from wireless phone RF exposures. However, none of the studies cananswer questions about long-term exposures, since the average period ofphone use in these studies was around three years.What research is needed to decide whether RF exposure from wirelessphones poses a health risk?A combination of laboratory studies and epidemiological studies of peopleactually using wireless phones would provide some of the data that are needed.Lifetime animal exposure studies could be completed in a few years. However,very large numbers of animals would be needed to provide reliable proof of acancer promoting effect if one exists. Epidemiological studies can provide datathat is directly applicable to human populations, but 10 or more years' follow-up may be needed to provide answers about some health effects, such ascancer. This is because the interval between the time of exposure to a cancer-causing agent and the time tumors develop - if they do - may be many, manyyears. The interpretation of epidemiological studies is hampered by difficultiesin measuring actual RF exposure during day-to-day use of wireless phones.Many factors affect this measurement, such as the angle at which the phone isheld, or which model of phone is used.What is FDA doing to find out more about the possible health effects ofwireless phone RF?FDA is working with the U.S. National Toxicology Program and with groups ofinvestigators around the world to ensure that high priority animal studies areconducted to address important questions about the effects of exposure toradiofrequency energy (RF).FDA has been a leading participant in the World Health OrganizationInternational Electromagnetic Fields (EMF) Project since its inception in 1996.
