Cellular telephone addicts may risk more than the ire of their neighbors, who are forced to listen to them. A recent study shows that microwave radiation similar to that emitted by cell phones could tamper with long-term memory. Biologist Henry Lai of the University of Washington and his colleagues zapped 40 rats with microwave radiation to approximate the effects of intensive phone use. "When people use cell phones, 60 to 70 percent of the microwave radiation that's emitted is concentrated in the head and hand. We didn't have a tiny cell phone, so we exposed the whole animal," Lai says. The radiation dose directed at the rats' brains was less than the amount a human user's brain would receive, although the rats were exposed for one hour--much longer than a typical cell phone call. As a memory test, Lai dropped irradiated and non-irradiated rats into a tank of water and taught them to swim to a platform where they could dry off. He repeated the process six times to give the animals time to learn the task. The rats that had been exposed to microwaves took significantly longer than the control group to find the platform, and they often just tried to crawl out of the tank. The researchers suspect microwave radiation causes a decline in the rats' levels of acetylcholine, a brain chemical crucial for memory and learning. "They've lost the ability to form a map in their head," says Lai. Not surprisingly, he doesn't use a cell phone.