PubMed · 3134995
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1988-05-14. Cyclists and helmets.. https://doi.org/10.1136/bmj.296.6633.1397
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The role of Delta(9)-tetrahydrocannabinol (THC) in driver impairment and motor vehicle crashes has traditionally been established in experimental and epidemiological studies. Experimental studies have repeatedly shown that THC impairs cognition, psychomotor function and actual driving performance in a dose related manner. The degree of performance impairment observed in experimental studies after doses up to 300 microg/kg THC were equivalent to the impairing effect of an alcohol dose producing a blood alcohol concentration (BAC) >/=0.05 g/dl, the legal limit for driving under the influence in most European countries. Higher doses of THC, i.e. >300 microg/kg THC have not been systematically studied but can be predicted to produce even larger impairment. Detrimental effects of THC were more prominent in certain driving tasks than others. Highly automated behaviors, such as road tracking control, were more affected by THC as compared to more complex driving tasks requiring conscious control. Epidemiological findings on the role of THC in vehicle crashes have sometimes contrasted findings from experimental research. Case-control studies generally confirmed experimental data, but culpability surveys showed little evidence that crashed drivers who only used cannabis are more likely to cause accidents than drug free drivers. However, most culpability surveys have established cannabis use among crashed drivers by determining the presence of an inactive metabolite of THC in blood or urine that can be detected for days after smoking and can only be taken as evidence for past use of cannabis. Surveys that established recent use of cannabis by directly measuring THC in blood showed that THC positives, particularly at higher doses, are about three to seven times more likely to be responsible for their crash as compared to drivers that had not used drugs or alcohol. Together these epidemiological data suggests that recent use of cannabis may increase crash risk, whereas past use of cannabis does not. Experimental and epidemiological research provided similar findings concerning the combined use of THC and alcohol in traffic. Combined use of THC and alcohol produced severe impairment of cognitive, psychomotor, and actual driving performance in experimental studies and sharply increased the crash risk in epidemiological analyses.
OBJECTIVE: To investigate whether the risk of motorcycle crash related injuries is associated with the conspicuity of the driver or vehicle. DESIGN: Population based case-control study. SETTING: Auckland region of New Zealand from February 1993 to February 1996. PARTICIPANTS: 463 motorcycle drivers (cases) involved in crashes leading to hospital treatment or death; 1233 motorcycle drivers (controls) recruited from randomly selected roadside survey sites. MAIN OUTCOME MEASURES: Estimates of relative risk of motorcycle crash related injury and population attributable risk associated with conspicuity measures, including the use of reflective or fluorescent clothing, headlight operation, and colour of helmet, clothing, and motorcycle. RESULTS: Crash related injuries occurred mainly in urban zones with 50 km/h speed limit (66%), during the day (63%), and in fine weather (72%). After adjustment for potential confounders, drivers wearing any reflective or fluorescent clothing had a 37% lower risk (multivariate odds ratio 0.63, 95% confidence interval 0.42 to 0.94) than other drivers. Compared with wearing a black helmet, use of a white helmet was associated with a 24% lower risk (multivariate odds ratio 0.76, 0.57 to 0.99). Self reported light coloured helmet versus dark coloured helmet was associated with a 19% lower risk. Three quarters of motorcycle riders had their headlight turned on during the day, and this was associated with a 27% lower risk (multivariate odds ratio 0.73, 0.53 to 1.00). No association occurred between risk and the frontal colour of drivers' clothing or motorcycle. If these odds ratios are unconfounded, the population attributable risks are 33% for wearing no reflective or fluorescent clothing, 18% for a non-white helmet, 11% for a dark coloured helmet, and 7% for no daytime headlight operation. CONCLUSIONS: Low conspicuity may increase the risk of motorcycle crash related injury. Increasing the use of reflective or fluorescent clothing, white or light coloured helmets, and daytime headlights are simple, cheap interventions that could considerably reduce motorcycle crash related injury and death.
CONTEXT: A car occupant could be killed if struck by another occupant who was catapulted forward, backward, or sideways in a crash. OBJECTIVE: To estimate the association between death of a car occupant (the target) and restraint use by other occupants. DESIGN: Matched-pair cohort study comparing the outcomes of 2 target occupants in the same passenger car that crashed. SETTING: United States traffic crashes in 1988-2000, using data from the Fatality Analysis Reporting System. SUBJECTS: Target pairs, at least 1 of whom died: 61 834 front-seat pairs, 5278 rear-seat pairs, and 21 127 pairs on the left or right side. MAIN OUTCOME MEASURES: Adjusted risk ratio (RR) for death within 30 days of a crash. RESULTS: The risk of death was greater for a restrained front target occupant in front of an unrestrained occupant compared with a restrained front target in front of a restrained occupant (adjusted RR, 1.20; 95% confidence interval [CI], 1.10-1.31). For a restrained rear target occupant behind an unrestrained occupant compared with a restrained rear target occupant behind a restrained occupant, the adjusted RR was 1.22 (95% CI, 1.10-1.36). For a restrained side target occupant sitting next to an unrestrained occupant compared with a restrained side target occupant sitting next to a restrained occupant, the adjusted RR was 1.15 (95% CI, 1.08-1.22). Among unrestrained target occupants, the adjusted RRs were, for front targets, 1.04 (95% CI, 0.97-1.12), rear targets, 1.22 (95% CI, 1.10-1.36), and side targets, 0.85 (95% CI, 0.80-0.92). CONCLUSION: Persons who wish to reduce their risk of death in a crash should wear their own restraint and should ask others in the same car to use their restraints.