More research on cell phones causing crashes

She allows as how the finding with hands-free phones "isn't intuitive. You'd think using a hands-free phone would be less distracting, so it wouldn't increase crash risk as much as using a hand-held phone. But we found that either phone type increased the risk."

McCartt suggests this could be because the "so-called hands-free phones that are in common use today aren't really hands-free. We didn't have sufficient data to compare the different types of hands-free phones, such as those that are fully voice-activated."

The findings of the study in Australia are consistent with Canadian research that showed phone use was associated with a fourfold increase in the risk of a property damage crash.

Like that study, the latest study by the IIHS (which is funded by many of the insurance companies in the U.S.) used phone records, but it's the first to estimate whether and how much phone use increases the risk of an injury crash.

Taken together, says McCartt, "the two studies confirm that the distractions associated with phone use contribute significantly to crashes."

Other studies have been published about cell phone use while driving, she says, "but most have been small-scale and have involved simulated or instrumented driving, not the actual experience of drivers on the road. When researchers have tried to assess the effects of phone use on real-world crashes, they usually have relied on police reports for information. But such reports aren't reliable because, without witnesses, police cannot determine whether a crash-involved driver was using a phone."

But this study, like the Canadian one from eight years ago, clearly indicates that using a cell phone of any kind in a car significantly increases the risk of getting into a crash.