"We tried to mimic a high level of exposure that humans might experience," says study leader Joseph L. Roti Roti, Ph.D., professor of radiation oncology, of biochemistry and molecular biophysics and of cell biology and physiology.
"We found no statistically significant increases in any tumor type, including brain, liver, lung or kidney, compared to the control group."
Roti Roti will present the findings on June 25 at the Bioelectromagnetic Society meeting in Quebec City, Quebec.
For more than a decade, a public debate has asked whether cell phone radiation causes cancer, particularly brain cancer. Roti Roti's long-term, industry-funded study was undertaken to address that question. The research examined whether chronic exposure to radio frequency (RF) radiation at two common cell phone signals - 835.62 megahertz, a frequency used by analogue cell phones, and 847.74 megahertz, a frequency used by digital cell phones - caused brain tumors in rats.
The study used 480 male and female rats. One third of the animals were exposed to the analogue cell phone frequency, one-third to the digital frequency and one-third served as controls and received no radiation.
After two years and a total of 505 days of exposure, the brain, spinal cord and other organs from each animal were studied microscopically for signs of cancer.
"We looked specifically for brain and spinal cord tumors," says Marie C. La Regina, D.V.M., a veterinary pathologist with the University's Division of Comparative Medicine and the lead author on the study. "We examined 20 to 25 sections from each brain microscopically, which is more than is usually done when studying potential cancer-causing agents. We didn't want to miss anything."
The investigators also looked for tumors in nearly 30 other tissues, as well. They found no statistically significant increases in any tumor type. They also found no differences in weight or life span between exposed and control animals.
This study builds on research begun by Roti Roti in 1995. In his earlier work, he exposed laboratory-grown cells to cell phone radiation and then studied the cells for genetic damage, gene expression and neoplastic transformation. Those experiments also showed no effect from the exposure.
"As far as I can tell from the work so far," says Roti Roti, "the greatest hazard with cell-phones is driving a car while talking on one."
La Regina M, Moros E, Pickard W, Straube W, Roti Roti JL. The effect of chronic exposure to 835.62 MHz FMCW or 847.7 MHz CDMA on the incidence of spontaneous tumors in rats. Bioelectromagnetic Society Conference. June 25, 2002.
This research was supported by funding from Motorola Inc. and from Integrated Laboratory Systems.