91Health and safety informationstudies investigated any possible associationbetween the use of wireless phones and primarybrain cancer, glioma, meningioma, or acousticneuroma, tumors of the brain or salivary gland,leukemia, or other cancers. None of the studiesdemonstrated the existence of any harmful healtheffects from wireless phones RF exposures.However, none of the studies can answer questionsabout long-term exposures, since the averageperiod of phone use in these studies was aroundthree years.What research is needed to decide whetherRF exposure from wireless phones poses ahealth risk?A combination of laboratory studies andepidemiological studies of people actually usingwireless phones would provide some of the data thatare needed. Lifetime animal exposure studies couldbe completed in a few years. However, very largenumbers of animals would be needed to providereliable proof of a cancer promoting effect if oneexists. Epidemiological studies can provide data thatis directly applicable to human populations, but tenor more years' follow-up may be needed to provideanswers about some health effects, such as cancer.This is because the interval between the time ofexposure to a cancer-causing agent and the timetumors develop - if they do - may be many, manyyears. The interpretation of epidemiological studiesis hampered by difficulties in measuring actual RFexposure during day-to-day use of wireless phones.Many factors affect this measurement, such as theangle at which the phone is held, or which model ofphone is used.What is FDA doing to find out more aboutthe possible health effects of wirelessphone RF?FDA is working with the U.S. National ToxicologyProgram and with groups of investigators around theworld to ensure that high priority animal studies areconducted to address important questions about theeffects of exposure to radio frequency energy(RF).FDA has been a leading participant in the WorldHealth Organization international ElectromagneticFields (EMF) Project since its inception in 1996. Aninfluential result of this work has been thedevelopment of a detailed agenda of research needsthat has driven the establishment of new researchprograms around the world. The Project has alsohelped develop a series of public informationdocuments on EMF issues.FDA and CellularTelecommunications & Internet Association (CTIA)have a formal Cooperative Research andDevelopment Agreement (CRADA) to do research onwireless phone safety. FDA provides the scientificoversight, obtaining input from experts ingovernment, industry, and academic organizations.