Cannabis intoxication and fatal road crashes in France: population based case-control study

Abstract

Objectives To evaluate the relative risk of being responsible for a fatal crash while driving under the influence of cannabis, the prevalence of such drivers within the driving population, and the corresponding share of fatal crashes. Design Population based case-control study. Participants 10 748 drivers, with known drug and alcohol concentrations, who were involved in fatal crashes in France from October 2001 to September 2003. Main outcome measures The cases were the 6766 drivers considered at fault in their crash; the controls were 3006 drivers selected from the 3982 other drivers. Positive detection of cannabis was defined as a blood concentration of 9 tetrahydrocannabinol of over 1 ng/ml. The prevalence of positive drivers in the driving population was estimated by standardising controls on drivers not at fault who were involved in crashes resulting in slight injuries. Results 681 drivers were positive for cannabis (cases 8.8%, controls 2.8%), including 285 with an illegal blood alcohol concentration ( ≥ 0.5 g/l). Positive cannabis detection was associated with increased risk of responsibility (odds ratio 3.32, 95% confidence interval 2.63 to 4.18). A significant dose effect was identified; the odds ratio increased from 2.18 (1.22 to 3.89) if 0 < 9 tetrahydrocannabinol < 1 ng/ml to 4.72 (3.04 to 7.33) if 9 tetrahydrocannabinol ≥ 5 ng/ml. The effect of cannabis remains significant after adjustment for different cofactors, including alcohol, with which no statistical interaction was observed. The prevalence of cannabis (2.9%) estimated for the driving population is similar to that for alcohol (2.7%). At least 2.5% (1.5% to 3.5%) of fatal crashes were estimated as being attributable to cannabis, compared with 28.6% for alcohol (26.8% to 30.5%). Conclusions Driving under the influence of cannabis increases the risk of involvement in a crash. However, in France its share in fatal crashes is significantly lower than that associated with positive blood alcohol concentration.

Predictors of driving after alcohol and drug use among adolescents in Valencia (Spain)

“…As the night passes, students reported more frequent use of cocaine, ecstasy, and LSD. Multiple drug use, as found in the present study, has been reported for the population, in particular for the young adults (Furr-Holden et al, 2006;Midanik et al, 2007), which leads to an increased effect on psychomotor performance, as well as an increase in traffic accident risk (Laumon et al, 2005;Ramaekers et al, 2004Ramaekers et al, , 2006Richer and Bergeron, 2009). It should be mentioned that, in the present study, no information was recorded regarding exposure in terms of kilometres driven.…”

Toxicological findings in driver and motorcyclist fatalities in Scotland 2012–2015

“…The percentage of cannabis positive cases in this study is higher than the 3% reported in Sweden (as THC) [17], 7% reported in France (as THC) [11] and 9.8% reported in the USA (analyte not stated) [25]. But lower than the 27% reported in Canada (as THC and/or carboxy-THC) [1] and 30% reported in New Zealand (as THC) [13].…”

“…This is lower than all of the similar studies reported in the literature, including the 21% in Sweden (limit = 20 mg/100 mL) [17], 11% in France (limit = 50 mg/100 mL) [11], 25% in Norway (limit = 20 mg/100 mL) [14], 36% in Brazil (zero tolerance) [8], and 29% in Australia (limit = 50 mg/100 mL) [7]. Of the alcohol-positive drivers, 75%…”

“…Surveys of the incidence of drugs and alcohol in MVCs have been carried out in numerous countries, including Australia [7], Brazil [8], Canada [1], England & Wales [9,10], France [11], Jordan [12], New Zealand [13], Norway [14,15], Spain [16], Sweden [17] and other Northern European Countries [18], and the USA [19]. However, little is known about how frequently drugs are involved in fatal MVCs in Scotland, with the last detailed study having been published in 1999, and then only for the Strathclyde region [20].…”

Road crash involvement and professional status: A prospective study using the French Gazel cohort

“…The aim is to focus on the role of factors directly associated with road activities (VKT and direct measures of road behaviours) in the PS-RCI association. The studied driving behaviours were those available in the cohort and previously found to be associated with road safety in analyses of the GAZEL cohort or in the literature: mobile phone use (Laberge-Nadeau et al 2003), drowsiness (Nabi et al 2006), driving under the influence of alcohol (Laumon et al 2005), speeding in built up areas or on rural roads or motorways (Lagarde et al 2004b), other infringements of the Highway Code (Lagarde et al 2004b)and whether or not the subject declared himself cautious while driving. The use of a motorized two-wheeled vehicle was also studied.…”