One of the first researchers to study the effects of driving and using a cell phone is calling on governments to ban drivers from using their phones.

Dr. Donald Redelmeier says his original study underestimated the risks.

Redelmeier says even the briefest conversation on a cell phone is dangerous, while driving.

His 1997 study found that drivers were four times more likely to have an accident while using cell phones.

"So that's above and beyond all the customary distractions of listening to the radio or talking to a fellow passenger ... there's something distinctly more hazardous about using a cellular phone than these other in-car behaviors," says Redelmeier.

In April, a man and his two-year-old daughter died at a Mississauga, Ontario railway crossing when a train smashed into their pick-up truck.

It's believed the father was talking on his phone when he drove on to the tracks.

Cell phone manufacturers say laws aren't the answer. They say people have to be taught to use their cell phones safely.