Muscat and colleagues caution that more research is needed to determine health effects of long-term phone use. The research, funded by federal and cell phone industry grants, compared cell phone habits of 469 people with brain cancer to those of 422 healthy people matched by age, sex and other characteristics. Study participants in the group with cancer averaged 2.5 hours of phone use per month, while the control group averaged 2.2 hours per month. Except for preliminary results from a Swedish study, which also found no risk from the phones, there have been no studies on how cell phones affect humans, Muscat says. The industry has now moved to digital,'' he says, and ''some of the research shown in animals has found no effect in analog but some concern in digital.
Muscat says studies are underway in Europe to investigate the possible risks of digital cell phones.