The National Safety Council is all over the press calling for an immediate ban on the use of cellphones while driving. No actual study is referenced. Are they citing a newer study? What study?
(I understand your interest in seeing a study, but surely you don't expect a political campaign to seek justification on the basis of an academic (!) study?) Anyway, I found this one: A Revised Economic Analysis of Restrictions on the Use of Cell Phones While Driving, by Cohen, Joshua T.; Graham, John D. Risk Analysis, Volume 23, Number 1, February 2003.
In recent years, Cohen's published research has focused on fish consumption, mercury intake, and consequent effects on prenatal health and heart disease. In the 1980's and 1990's, Graham published several studies on automobile safety. Here's the abstract: Evidence that cell phone use while driving increases the risk of being involved in a motor vehicle crash has led policymakers to consider prohibitions on this practice. However, while restrictions would reduce property loss, injuries, and fatalities, consumers would lose the convenience of using these devices while driving. Quantifying the risks and benefits associated with cell phone use while driving is complicated by substantial uncertainty in the estimates of several important inputs, including the extent to which cell phone use increases a driver's risk of being involved in a crash, the amount of time drivers spend using cell phones (and hence their aggregate contribution to crashes, injuries, and fatalities), and the incremental value to users of being able to make calls while driving. Two prominent studies that have investigated cell phone use while driving have concluded that the practice should not be banned. One finds that the benefits of calls made while driving substantially exceed their costs while the other finds that other interventions could reduce motor vehicle injuries and fatalities (measured in terms of quality adjusted life years) at a lower cost. Another issue is that cell phone use imposes increased (involuntary) risks on other roadway users. This article revises the assumptions used in the two previous analyses to make them consistent and updates them using recent data. The result is a best estimate of zero for the net benefit of cell phone use while driving, a finding that differs substantially from the previous study. Our revised cost-effectiveness estimate for cell phone use while driving moves in the other direction, finding that the cost per quality adjusted life year increases modestly compared to the previous estimate. Both estimates are very uncertain.
Since its publication in 2003, this report has been cited by numerous other reports (and also by ban advocates). One widely cited 2006 study concluded: A number of jurisdictions in the United States and around the world have made it illegal for drivers to use hand-held phones. Studies of these laws show only limited compliance and unclear effects on safety. Conclusions. Even if total compliance with bans on drivers' hand-held cell phone use can be achieved, crash risk will remain to the extent that drivers continue to use or switch to hands-free phones. Although the enactment of laws limiting drivers' use of all phones is consistent with research findings, it is unclear how such laws could be enforced. At least in the short term, it appears that drivers' phone use will continue to increase, despite the growing evidence of the risk it creates. More effective countermeasures are needed but are not known at this time.
The trail runs cold as you walk the citations forward, but a 2007 working paper from Brookings might be of interest: Once we correct for the endogeneity of usage, our models predict no statistically significant increase in accidents from mobile phone usage, whether hand-held or hands-free. Our results call into question previous cost-benefit analyses of bans on mobile phone usage while driving, which typically assume that such bans will have a salutary effect.
RE: Cell Phone Use While Driving Fact Sheet | 
