I am not sure to what extent these revisions in road rules are directly driven by statistics or by other agendas.
I do remember that an episode of "Mythbusters" identified that somebody talking on a mobile phone was in less control of their vehicle than a person with some degree of BAC (I can't recall what limit they used as although this was an Aussie inspired production, the events took place in America.)
On a slightly different tack, we had a discussion at work on this whole subject and somebody came up with the statistic that there may be more people under the influence of drugs on the road than alcohol. If, and I stress if, that were true I would find that far more alarming. I am also aware that people pulled over for a breath test are also likely to be drug tested. I suspect, but don't know, that the drug test tends to only take place if the police are suspicious of the vehicle occupants as testing is still quite expensive.
Regards
Paul