Drivers who use cannabis up to three hours before driving are twice as likely to cause a collision as those not under the influence of drugs or alcohol, says a Canadian study.
有加拿大研究表明，抽大麻3小时之内驾驶引发车祸的概率是那些没有喝酒、没有抽大麻的二倍。
This is because cannabis impairs brain and motor functions needed for safe driving, the researchers suggest.
有研究说这是因为大麻损害大脑，而且降低人们的安全警惕。
The study in bmj.com reviewed nine studies of 50,000 people worldwide who had been in serious or fatal crashes.
研究成果发布在bmj.com，研究了九组发生车祸的驾驶者，一共有50000人。
Experts support the close monitoring of serious accidents involving drugs.
很多专家也认为抽大麻开车更容易引发车祸。
The study analysis was carried out by researchers at Dalhousie University in Halifax, Canada.
研究分析是由加拿大在哈利法克斯的达尔豪西大学的研究者做出的。
They looked at observational studies of collisions between one or more moving vehicles on a public road which involved the consumption of cannabis.
他们在公路上观察，看那些发生碰撞的驾驶者是否抽过大麻。
Drivers of cars, sports utility vehicles, vans, lorries, buses and motorcycles featured in the studies.
这项研究中驾驶者驾驶的车有轿车、越野车、卡车、公共汽车、摩托车。
The study found a near doubling of risk of a driver being involved in a motor vehicle collision resulting in serious injury or death if cannabis had been consumed less than three hours before.
最终得出的结论吸食大麻在3小时之内使车祸发生的概率增加一倍。
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A system needs to be put in place to monitor the number of serious and fatal accidents where impairment from illegal drugs was a contributory factor.” Duncan VernonRoyal Society for the Prevention of Accidents
“ 我们需要一个合适的方法，去证明车祸在多大程度上是由吸食大麻引发身体伤害。”事故预防协会的邓肯说道
However, it added that the impact of acute cannabis consumption on the risk of minor crashes was still unclear. Blood sample
但是，吸食大麻对车祸到底有没有危害还没确定。
Mark Asbridge, study author and associate professor at the department of community health and epidemiology at Dalhousie University, said the research was important.
Mark Asbridge，该研究的作者、达尔豪西大学的社区卫生和流行病学系的副教授。认为这项研究是重要的。
"Our findings provide clarity to the large body of research on cannabis and collision risk.
我们的研究为吸食大麻和车祸之间的关系提供了思路。
"They also offer support to existing policies, in many jurisdictions, that restrict driving under the influence of cannabis, and direct public health officials to devote greater attention to this issue."
我们这样做为现在很多司法管辖区存在的政策提供了支持。例如禁止在吸食大麻的情况下开车，同时也引起公共健康部门对这个问题更多的重视。
All studies tested for tetrahydrocannabinol, or THC, the active chemical in cannabis, by analysing blood samples or using direct reports of cannabis use from those involved.
四氢大麻酚的测试，或者叫THC,是大麻中的活跃物质，我们主要检测血液中有没有THC来判断司机是否抽过大麻。
Most studies used one nanogram per millilitre of cannabis or any amount greater than zero as the cut-off for a positive test result, with one study using a 2ng/ml cut-off.
Duncan Vernon, a road safety manager at the Royal Society for the Prevention of Accidents (RoSPA), said that previous studies in controlled lab conditions had shown that cannabis can impair a driver's ability to respond to potential dangers.
Duncan Vernon，预防事故安全协会经理，说之前在实验室表明大麻降低人对危险情况的应急能力。
"This new research strengthens the evidence that driving under the influence of cannabis increases the likelihood of being seriously injured or killed in a collision.
这个研究更是人们坚信，在吸食大麻的情况下，增加了交通事故的可能性。所以我们应该采取积极的行动防止它发生。
"This adds to the argument that a system needs to be put in place to monitor the number of serious and fatal accidents where impairment from illegal drugs was a contributory factor, so that appropriate action can be taken to prevent them." Positive test
Julie Townsend, deputy chief executive of road safety charity Brake, said that tackling drug driving should be a top priority.
Julie Townsend，道路安全制动副总裁，说打击药后驾驶是当务之急。
"This report highlights the danger posed by drivers who have smoked cannabis and adds weight to Brake's calls for widespread testing and prosecution of drivers."
这项报告突出了药后驾驶的危险，所以我们要大范围的检测司机是不是在抽大麻的情况下开车。
In the UK, 18% of people killed in road crashes have traces of illegal drugs in their blood, with cannabis the most common, Brake says.
在英国18%的死于交通事故的司机有过抽大麻，通过血检检测。
The Canadian study cites a roadside survey of 537 drivers in Scotland in 2000 which found that 15% of respondents aged 17-39 years admitted to having consumed cannabis within 12 hours of driving a vehicle.
加拿大引用一个苏格兰2000年537个司机的调查，在17-39的司机有15%承认他们在驾驶之前的12个小时有吸过大麻。
The European Monitoring Centre for Drugs and Drug Addiction found, in 2008, that between 0.3% and 7.4% of drivers tested positive for cannabis from roadside surveys in the United Kingdom, Denmark, the Netherlands, Norway, the United States, and Australia.
欧洲毒品和毒瘾检测中心，在2008年，对英国、丹麦、荷兰、挪威、美国和澳大利亚，通过路边检测，各个国家药后驾驶情况各有不同，最少的0.3%，最多的7.4%。
The researchers conclude that despite the increased risk posed by cannabis to car drivers, alcohol remains the substance most often present in crashes.
研究者认为尽管这几年由大麻引发的交通事故在增加，但是酒后驾驶依然是车祸的主要杀手。
The observed association between alcohol and crash risk is more significant than that for cannabis, the study says.
研究机构表明关于交通事故由喝酒引发的远远大于抽大麻的。
