ABSTRACT
There is clear evidence that alcohol impairs the cognitive and motor skills required for safe driving. Reasonably sound evidence exists that the same is true for marijuana. At therapeutic dosages, benzodiazepine tranquilizers may increase the risk of a crash, but this is mainly during the first couple of weeks of use while tolerance to them is being developed. At present too few drivers take amphetamines, cocaine, and opiates for them to make much difference to the accident statistics. However, given the apparent rapidity with which illicit drug use is increasing in the general population, this may change. Of all drugs, alcohol is the biggest threat to road safety, both because of its widespread use and because of the nature of its effects on behavior. Alcohol is unequivocally a major cause of road accidents. Due to differences in various factors, such as driving conditions, traffic density, and the statistical and methodological techniques are used.
