Argentina Train Crash Kills Dozens and Injures 600

The train, which runs from the ring of urban areas that surround greater Buenos Aires, crashed at about 8:30 a.m. at its final stop at the Once Station, not far from downtown Buenos Aires.

The train was carrying more than 800 passengers and traveling at an estimated 16 miles per hour when it entered the station, slamming into the barrier of the platform, destroying the engine.

“It is a very serious accident,” Juan Pablo Schiavi, the national secretary of transportation, said in his initial assessment of the crash during a televised press conference outside the Once Station. Mr. Schiavi said brake failure was the suspected cause.

“The train hit the bumper,” Mr. Schiavi said, “causing one car to crumple into another.”

He said one car pierced into another by nearly 20 feet.

The injured were taken to hospitals in the vicinity, Dr. Alberto Crescenti, head of the state emergency medical system, said on Argentine television on Wednesday. He said around midday that about 30 people were trapped in the wreckage.

Passengers told the local news media that the train, which is operated by the private company Trenes de Buenos Aires, was traveling faster than normal and had struggled to slow down when braking at stations ahead of Once Station.

Trenes de Buenos Aires said in a statement that the reasons for the crash had not been determined, though the company acknowledged that the train “wasn’t able to stop.”

Video footage of the crash taken by people at the scene showed people walking along the platform, with screams audible. People were pulling others out of the wreckage.

“I saw a lot of people bleeding and some who were trapped,” said one survivor, a 23-year-old woman, quoted by the newspaper Clarín.

Last September, a commuter train on the same line crashed into a passenger bus and hit a second train at the Flores Station, killing 11 and injuring more than 200. The bus had crossed the tracks when the barrier was down. In February 2011, four people were killed in a collision of two trains.

The newspaper La Nación said the accident was the third-deadliest in Argentina’s history, surpassed only by a 1972 collision that killed 142 people and a 1978 accident involving trains and other vehicles that left 55 dead.

Charles Newbery reported from Pinamar, Argentina, and Simon Romero from Rio de Janeiro.

View the original article here

The Lede Blog: At least 49 dead, 550 injured in train crash in Once Station in Buenos Aires

Video broadcast by C5N, an Argentine news channel, of the moment a train hit a barrier in a station in Buenos Aires on Wednesday.

Updated | 2:09 p.m. A 7-year-old boy was among the first of the 49 people confirmed killed in a train crash in Buenos Aires that also left at least 550 people injured, according to local media reports, including The Buenos Aires Herald.

A packed train derailed at the Once Station, one of the city’s busy central train stations, and crashed at the end of the track about 8:30 a.m., trapping hundreds of commuters.

“There are people still trapped, people alive, and there may have been fatalities,” Argentina’s transport secretary, Juan Pablo Schiavi, told reporters before rescue workers, began removing the dead from the wreckage of twisted metal and shattered glass. According to Mr. Schiavi, the train was traveling at too high a speed when it approached the station, hitting the barrier at the end of the platform, crumpling the front engine and collapsing commuter rail cars behind it. Most of those killed were in the first two cars.

Video posted online by C5N, an Argentine news channel, showed security camera footage of the moment the train hit the barrier. The Argentine newspaper La Nacion’s report on the crash included two video clips shot from the platform shortly after the accident that show the damage to the train and passengers leaving the scene.

One of the passengers told reporters, according to local media reports: “I had people piled on top of me, none of us could move.”

To help find missing friends and family members, people turned to Twitter and other social tools asking for help, including this post seeking information about Lucas Menghini Rey and Tatiana Pontiroli.

Todo Padua busca a Lucas Menghini Rey y Tatiana Pontiroli. Que aparezcan por favor.

— Lucía. (@lululilucia) February 22, 2012

Several witnesses appear to have recorded images of the scene in the immediate aftermath of the crash. One injured man even showed a television crew video he shot on his phone, as he waited for treatment.

This is the second deadly train crash in Argentina in recent months. In September, a train flew through the air after hitting a bus and smashed into another train, killing at least 11 people and injuring 250. A security camera at the train station captured video of that accident as well.

View the original article here

Recent Pot Use Could Double Risk of Car Crash, Research Shows

THURSDAY, Feb. 9 (HealthDay News) -- Getting behind the wheel within three hours after using marijuana nearly doubles a driver's risk of having an accident, a large new research review finds.

The risk is especially high for fatal crashes, and the risk is only a little less than that of people who drive drunk, Canadian researchers say.

"On the whole, alcohol increases the risk of a crash at a higher level than cannabis [marijuana]," said lead researcher Mark Asbridge, an associate professor in the community health and epidemiology department at Dalhousie University, in Halifax.

But marijuana makes it harder to judge distance and drivers often tailgate and swerve from lane to lane, which cuts down their reaction time and leads to crashes, he explained.

Although the extent of the problem isn't known, some studies have found that 5 percent of people report driving after using marijuana; and for those under age 25, as many as 20 percent, Asbridge said.

Studies on the effect of driving under the influence of marijuana have had mixed results, he said.

"There were some studies finding that cannabis actually had a negative association with crash risk, so people were actually safer using cannabis driving than when they weren't, but these were poorly designed studies," Asbridge said.

"So our study gives some clarity to the issue in showing a doubling of the risk in the very best studies that are out there and adds some level of justification to existing policies that restrict drug-impaired driving," he said.

The report was published in the Feb. 10 online edition of the BMJ.

To see how marijuana affected driving, Asbridge's team reviewed nine studies that included more than 49,000 people. This process -- called a meta-analysis -- looks for patterns across studies.

The researchers found that those driving under the influence of marijuana were nearly twice as likely to have a car crash as those who were not under the influence.

Studies outside the review have shown that drivers aged 35 and younger are more likely to have car accidents after using marijuana, the authors noted.

"These findings reaffirm many of our accepted understandings regarding acute cannabis intoxication and psychomotor performance," said Paul Armentano, deputy director of NORML (the National Organization for the Reform of Marijuana Laws). "That is why operating a motor vehicle while acutely impaired by cannabis is presently a criminal offense in all 50 states."

This risk appears to be greatest in less-experienced cannabis users, younger drivers, and among those who combine the use of cannabis and alcohol, Armentano pointed out.

"That said, it should further be noted that cannabis-induced changes in performance are typically subtle, short-lived and less dramatic in more experienced cannabis consumers, who appear to develop tolerance to some of the drug's behavioral effects," he added.

"Further, this overall elevated risk is far less than the elevated risk of accidents associated with the consumption of alcohol, including its use in legal quantities," Armentano said.

While some suggest that drivers should be tested for marijuana, so far, no effective test exists that can be done at a traffic stop to accurately pinpoint when a driver used the drug.

"This evidence makes a case for introducing policies to reduce cannabis-impaired driving," said Wayne Hall, from the University of Queensland Centre for Clinical Research in Brisbane, Australia. He wrote an accompanying editorial for the journal.

He said that roadside drug testing, such as that used for alcohol, may be a useful approach.

But there are no handy devices, such as a breathalyzer, to tell if someone has recently used marijuana, Asbridge noted.

"The challenge is defining a level that equates with impairment. A number of countries have already introduced roadside testing by deciding that any detectable evidence of recent use constitutes impaired driving. However, we do not know how effective testing has been because the policy has not been evaluated," Hall said.

Another expert outlined the problems with such tests.

"Because THC, the active ingredient in marijuana, can be detected several weeks after use of marijuana, it is hard to determine with certainty if a driver testing positive for marijuana is indeed impaired by the substance at the time of testing," said Dr. Guohua Li, a professor of epidemiology at Columbia University in New York City.

So more research is needed. "This issue is especially urgent and important in light of the ongoing epidemic of drugged driving and increased permissibility and availability of marijuana worldwide," Li said.

While recognition that driving under the influence of marijuana is a problem is a first step in finding ways to curb it, Jan Withers, national president of Mothers Against Drunk Driving (MADD), stated that "drunk driving remains the primary threat to our families on the road."

However, she added, "this study underscores the importance of the work that MADD is doing to support people who have been victimized by drugged driving and recognize law-enforcement's efforts to pioneer effective strategies to stop drugged driving. Notably, it shows the increased danger posed by those drivers using both alcohol and drugs."

More information

For more about drugged driving, visit the U.S. National Institute on Drug Abuse.

View the original article here

Pot Use Could Double Risk of Car Crash, Research Shows

THURSDAY, Feb. 9 (HealthDay News) -- Getting behind the wheel within three hours after using marijuana nearly doubles a driver's risk of having an accident, a large new research review finds.

The risk is especially high for fatal crashes, and the risk is only a little less than that of people who drive drunk, Canadian researchers say.

"On the whole, alcohol increases the risk of a crash at a higher level than cannabis [marijuana]," said lead researcher Mark Asbridge, an associate professor in the community health and epidemiology department at Dalhousie University, in Halifax.

But marijuana makes it harder to judge distance and drivers often tailgate and swerve from lane to lane, which cuts down their reaction time and leads to crashes, he explained.

Although the extent of the problem isn't known, some studies have found that 5 percent of people report driving after using marijuana; and for those under age 25, as many as 20 percent, Asbridge said.

Studies on the effect of driving under the influence of marijuana have had mixed results, he said.

"There were some studies finding that cannabis actually had a negative association with crash risk, so people were actually safer using cannabis driving than when they weren't, but these were poorly designed studies," Asbridge said.

"So our study gives some clarity to the issue in showing a doubling of the risk in the very best studies that are out there and adds some level of justification to existing policies that restrict drug-impaired driving," he said.

The report was published in the Feb. 10 online edition of the BMJ.

To see how marijuana affected driving, Asbridge's team reviewed nine studies that included more than 49,000 people. This process -- called a meta-analysis -- looks for patterns across studies.

The researchers found that those driving under the influence of marijuana were nearly twice as likely to have a car crash as those who were not under the influence.

Studies outside the review have shown that drivers aged 35 and younger are more likely to have car accidents after using marijuana, the authors noted.

"These findings reaffirm many of our accepted understandings regarding acute cannabis intoxication and psychomotor performance," said Paul Armentano, deputy director of NORML (the National Organization for the Reform of Marijuana Laws). "That is why operating a motor vehicle while acutely impaired by cannabis is presently a criminal offense in all 50 states."

This risk appears to be greatest in less-experienced cannabis users, younger drivers, and among those who combine the use of cannabis and alcohol, Armentano pointed out.

"That said, it should further be noted that cannabis-induced changes in performance are typically subtle, short-lived and less dramatic in more experienced cannabis consumers, who appear to develop tolerance to some of the drug's behavioral effects," he added.

"Further, this overall elevated risk is far less than the elevated risk of accidents associated with the consumption of alcohol, including its use in legal quantities," Armentano said.

While some suggest that drivers should be tested for marijuana, so far, no effective test exists that can be done at a traffic stop to accurately pinpoint when a driver used the drug.

"This evidence makes a case for introducing policies to reduce cannabis-impaired driving," said Wayne Hall, from the University of Queensland Centre for Clinical Research in Brisbane, Australia. He wrote an accompanying editorial for the journal.

He said that roadside drug testing, such as that used for alcohol, may be a useful approach.

But there are no handy devices, such as a breathalyzer, to tell if someone has recently used marijuana, Asbridge noted.

"The challenge is defining a level that equates with impairment. A number of countries have already introduced roadside testing by deciding that any detectable evidence of recent use constitutes impaired driving. However, we do not know how effective testing has been because the policy has not been evaluated," Hall said.

Another expert outlined the problems with such tests.

"Because THC, the active ingredient in marijuana, can be detected several weeks after use of marijuana, it is hard to determine with certainty if a driver testing positive for marijuana is indeed impaired by the substance at the time of testing," said Dr. Guohua Li, a professor of epidemiology at Columbia University in New York City.

So more research is needed. "This issue is especially urgent and important in light of the ongoing epidemic of drugged driving and increased permissibility and availability of marijuana worldwide," Li said.

While recognition that driving under the influence of marijuana is a problem is a first step in finding ways to curb it, Jan Withers, national president of Mothers Against Drunk Driving (MADD), stated that "drunk driving remains the primary threat to our families on the road."

However, she added, "this study underscores the importance of the work that MADD is doing to support people who have been victimized by drugged driving and recognize law-enforcement's efforts to pioneer effective strategies to stop drugged driving. Notably, it shows the increased danger posed by those drivers using both alcohol and drugs."

More information

For more about drugged driving, visit the U.S. National Institute on Drug Abuse.

View the original article here

Smoke and Mirrors: Driving While High on Marijuana Doubles One s Chances of a Serious Car Crash

pot_driving_accident Image courtesy of iStockphoto/Cabezonication

Booze is behind an estimated 2.1 million car accidents each year in the U.S. which cause almost 11,000 traffic fatalities annually. But many drug users have claimed that a few puffs of pot before getting behind the wheel are perfectly harmless. A new study, however, shows that drivers who smoke marijuana within a few hours of hitting the road are almost twice as likely as stone-sober motorists to be in a crash that results in serious injury or death.

Authors of the new paper, published online Thursday in the British Medical Journal (BMJ), sifted through nine previous studies to develop a clearer picture of the risks to users who light up before revving up. Previous studies have left the effects of marijuana on its own when not combined with alcohol or other drugs a little hazy.

But the researchers’ findings make sense to others in the field. “Their results are consistent with experimental evidence that cannabis use leads to dose related impairments in simulated driving, psychomotor skills and on-road driving,” Wayne Hall, of the University of Queensland’s Center for Clinical Research who was not involved in the new research, wrote in a related essay in BMJ.

In addition to the finding that drivers who had recently smoked pot were substantially more likely to be involved in a serious accident, the researchers found that those who had died in these crashes had higher amounts of the drug’s compound tetrahydrocannabinol than those who survived. But there was not enough data to link concentrations of the compound to various outcomes in order to suggest a threshold for dangerous intoxication, noted the researchers, who were led by Mark Asbridge, of Dalhousie University’s Department of Community Health and Epidemiology.

Driving while stoned has become a hot topic as more states allow for medical use of marijuana. The 2009 National Survey on Drug Use and Health found that more than 10 million people admitted to having driven while on at least one illegal drug with pot being the most common. More than a dozen states currently have roadside drug tests for cannabis that sample drivers’ saliva for traces of tetrahydrocannabinol. But, as Hall noted, ascertaining a dangerous level as is currently used in a breath-based test for alcohol (0.05 percent) is less clear cut. So far many governments are using a zero-tolerance rule, but, as Hall pointed out, “researchers have proposed a concentration of tetrahydrocannabinol below which driving is not impaired.”

Assessing the definitive risk for actually being in a car crash because of marijuana use is also tricky because studies haven’t always looked at drivers who were not determined to be “at fault” or passengers of vehicles or people involved in minor accidents.

Nevertheless, Asbridge and his colleagues noted, “This information could be used as the basis for campaigns against drug impaired driving.” But the roadside testing has not been as widely publicized as rapid alcohol breath tests have been, so the chance of getting “caught” with pot in one’s system doesn’t seem to have scared very many people into not smoking before driving. As Hall wrote, the idea that roadside tests for pot will reduce traffic fatalities as drastically and as rapidly as breathalyzers did for alcohol “is probably too optimistic.” But that doesn’t mean that attempts to stub out the dangerous habit should be written off just yet. “Better evidence is essential,” Hall said of the attempts to fight pot-impaired driving with more roadside testing.

Follow Scientific American on Twitter @SciAm and @SciamBlogs. Visit ScientificAmerican.com for the latest in science, health and technology news.
© 2012 ScientificAmerican.com. All rights reserved.

View the original article here

Smoke and Mirrors: Driving While on Marijuana Doubles One s Chances of a Serious Car Crash

pot_driving_accident Image courtesy of iStockphoto/Cabezonication

Booze is behind an estimated 2.1 million car accidents each year in the U.S. which cause almost 11,000 traffic fatalities annually. But many drug users have claimed that a few puffs of pot before getting behind the wheel are perfectly harmless. A new study, however, shows that drivers who smoke marijuana within a few hours of hitting the road are almost twice as likely as stone-sober motorists to be in a crash that results in serious injury or death.

Authors of the new paper, published online Thursday in the British Medical Journal (BMJ), sifted through nine previous studies to develop a clearer picture of the risks to users who light up before revving up. Previous studies have left the effects of marijuana on its own when not combined with alcohol or other drugs a little hazy.

But the researchers’ findings make sense to others in the field. “Their results are consistent with experimental evidence that cannabis use leads to dose related impairments in simulated driving, psychomotor skills and on-road driving,” Wayne Hall, of the University of Queensland’s Center for Clinical Research who was not involved in the new research, wrote in a related essay in BMJ.

In addition to the finding that drivers who had recently smoked pot were substantially more likely to be involved in a serious accident, the researchers found that those who had died in these crashes had higher amounts of the drug’s compound tetrahydrocannabinol than those who survived. But there was not enough data to link concentrations of the compound to various outcomes in order to suggest a threshold for dangerous intoxication, noted the researchers, who were led by Mark Asbridge, of Dalhousie University’s Department of Community Health and Epidemiology.

Driving while stoned has become a hot topic as more states allow for medical use of marijuana. The 2009 National Survey on Drug Use and Health found that more than 10 million people admitted to having driven while on at least one illegal drug with pot being the most common. More than a dozen states currently have roadside drug tests for cannabis that sample drivers’ saliva for traces of tetrahydrocannabinol. But, as Hall noted, ascertaining a dangerous level as is currently used in a breath-based test for alcohol (0.05 percent) is less clear cut. So far many governments are using a zero-tolerance rule, but, as Hall pointed out, “researchers have proposed a concentration of tetrahydrocannabinol below which driving is not impaired.”

Assessing the definitive risk for actually being in a car crash because of marijuana use is also tricky because studies haven’t always looked at drivers who were not determined to be “at fault” or passengers of vehicles or people involved in minor accidents.

Nevertheless, Asbridge and his colleagues noted, “This information could be used as the basis for campaigns against drug impaired driving.” But the roadside testing has not been as widely publicized as rapid alcohol breath tests have been, so the chance of getting “caught” with pot in one’s system doesn’t seem to have scared very many people into not smoking before driving. As Hall wrote, the idea that roadside tests for pot will reduce traffic fatalities as drastically and as rapidly as breathalyzers did for alcohol “is probably too optimistic.” But that doesn’t mean that attempts to stub out the dangerous habit should be written off just yet. “Better evidence is essential,” Hall said of the attempts to fight pot-impaired driving with more roadside testing.

Follow Scientific American on Twitter @SciAm and @SciamBlogs. Visit ScientificAmerican.com for the latest in science, health and technology news.
© 2012 ScientificAmerican.com. All rights reserved.

View the original article here

Smoke and Mirrors: Driving While High on Marijuana Doubles One s Chances of a Serious Car Crash

pot_driving_accident Image courtesy of iStockphoto/Cabezonication

Booze is behind an estimated 2.1 million car accidents each year in the U.S. which cause almost 11,000 traffic fatalities annually. But many drug users have claimed that a few puffs of pot before getting behind the wheel are perfectly harmless. A new study, however, shows that drivers who smoke marijuana within a few hours of hitting the road are almost twice as likely as stone-sober motorists to be in a crash that results in serious injury or death.

Authors of the new paper, published online Thursday in the British Medical Journal (BMJ), sifted through nine previous studies to develop a clearer picture of the risks to users who light up before revving up. Previous studies have left the effects of marijuana on its own when not combined with alcohol or other drugs a little hazy.

But the researchers’ findings make sense to others in the field. “Their results are consistent with experimental evidence that cannabis use leads to dose related impairments in simulated driving, psychomotor skills and on-road driving,” Wayne Hall, of the University of Queensland’s Center for Clinical Research who was not involved in the new research, wrote in a related essay in BMJ.

In addition to the finding that drivers who had recently smoked pot were substantially more likely to be involved in a serious accident, the researchers found that those who had died in these crashes had higher amounts of the drug’s compound tetrahydrocannabinol than those who survived. But there was not enough data to link concentrations of the compound to various outcomes in order to suggest a threshold for dangerous intoxication, noted the researchers, who were led by Mark Asbridge, of Dalhousie University’s Department of Community Health and Epidemiology.

Driving while stoned has become a hot topic as more states allow for medical use of marijuana. The 2009 National Survey on Drug Use and Health found that more than 10 million people admitted to having driven while on at least one illegal drug with pot being the most common. More than a dozen states currently have roadside drug tests for cannabis that sample drivers’ saliva for traces of tetrahydrocannabinol. But, as Hall noted, ascertaining a dangerous level as is currently used in a breath-based test for alcohol (0.05 percent) is less clear cut. So far many governments are using a zero-tolerance rule, but, as Hall pointed out, “researchers have proposed a concentration of tetrahydrocannabinol below which driving is not impaired.”

Assessing the definitive risk for actually being in a car crash because of marijuana use is also tricky because studies haven’t always looked at drivers who were not determined to be “at fault” or passengers of vehicles or people involved in minor accidents.

Nevertheless, Asbridge and his colleagues noted, “This information could be used as the basis for campaigns against drug impaired driving.” But the roadside testing has not been as widely publicized as rapid alcohol breath tests have been, so the chance of getting “caught” with pot in one’s system doesn’t seem to have scared very many people into not smoking before driving. As Hall wrote, the idea that roadside tests for pot will reduce traffic fatalities as drastically and as rapidly as breathalyzers did for alcohol “is probably too optimistic.” But that doesn’t mean that attempts to stub out the dangerous habit should be written off just yet. “Better evidence is essential,” Hall said of the attempts to fight pot-impaired driving with more roadside testing.

Follow Scientific American on Twitter @SciAm and @SciamBlogs. Visit ScientificAmerican.com for the latest in science, health and technology news.
© 2012 ScientificAmerican.com. All rights reserved.

View the original article here

Recent Pot Use Could Double Risk of Car Crash, Research Shows

THURSDAY, Feb. 9 (HealthDay News) -- Getting behind the wheel within three hours after using marijuana nearly doubles a driver's risk of having an accident, a large new research review finds.

The risk is especially high for fatal crashes, and the risk is only a little less than that of people who drive drunk, Canadian researchers say.

"On the whole, alcohol increases the risk of a crash at a higher level than cannabis [marijuana]," said lead researcher Mark Asbridge, an associate professor in the community health and epidemiology department at Dalhousie University, in Halifax.

But marijuana makes it harder to judge distance and drivers often tailgate and swerve from lane to lane, which cuts down their reaction time and leads to crashes, he explained.

Although the extent of the problem isn't known, some studies have found that 5 percent of people report driving after using marijuana; and for those under age 25, as many as 20 percent, Asbridge said.

Studies on the effect of driving under the influence of marijuana have had mixed results, he said.

"There were some studies finding that cannabis actually had a negative association with crash risk, so people were actually safer using cannabis driving than when they weren't, but these were poorly designed studies," Asbridge said.

"So our study gives some clarity to the issue in showing a doubling of the risk in the very best studies that are out there and adds some level of justification to existing policies that restrict drug-impaired driving," he said.

The report was published in the Feb. 10 online edition of the BMJ.

To see how marijuana affected driving, Asbridge's team reviewed nine studies that included more than 49,000 people. This process -- called a meta-analysis -- looks for patterns across studies.

The researchers found that those driving under the influence of marijuana were nearly twice as likely to have a car crash as those who were not under the influence.

Studies outside the review have shown that drivers aged 35 and younger are more likely to have car accidents after using marijuana, the authors noted.

"These findings reaffirm many of our accepted understandings regarding acute cannabis intoxication and psychomotor performance," said Paul Armentano, deputy director of NORML (the National Organization for the Reform of Marijuana Laws). "That is why operating a motor vehicle while acutely impaired by cannabis is presently a criminal offense in all 50 states."

This risk appears to be greatest in less-experienced cannabis users, younger drivers, and among those who combine the use of cannabis and alcohol, Armentano pointed out.

"That said, it should further be noted that cannabis-induced changes in performance are typically subtle, short-lived and less dramatic in more experienced cannabis consumers, who appear to develop tolerance to some of the drug's behavioral effects," he added.

"Further, this overall elevated risk is far less than the elevated risk of accidents associated with the consumption of alcohol, including its use in legal quantities," Armentano said.

While some suggest that drivers should be tested for marijuana, so far, no effective test exists that can be done at a traffic stop to accurately pinpoint when a driver used the drug.

"This evidence makes a case for introducing policies to reduce cannabis-impaired driving," said Wayne Hall, from the University of Queensland Centre for Clinical Research in Brisbane, Australia. He wrote an accompanying editorial for the journal.

He said that roadside drug testing, such as that used for alcohol, may be a useful approach.

But there are no handy devices, such as a breathalyzer, to tell if someone has recently used marijuana, Asbridge noted.

"The challenge is defining a level that equates with impairment. A number of countries have already introduced roadside testing by deciding that any detectable evidence of recent use constitutes impaired driving. However, we do not know how effective testing has been because the policy has not been evaluated," Hall said.

Another expert outlined the problems with such tests.

"Because THC, the active ingredient in marijuana, can be detected several weeks after use of marijuana, it is hard to determine with certainty if a driver testing positive for marijuana is indeed impaired by the substance at the time of testing," said Dr. Guohua Li, a professor of epidemiology at Columbia University in New York City.

So more research is needed. "This issue is especially urgent and important in light of the ongoing epidemic of drugged driving and increased permissibility and availability of marijuana worldwide," Li said.

While recognition that driving under the influence of marijuana is a problem is a first step in finding ways to curb it, Jan Withers, national president of Mothers Against Drunk Driving (MADD), stated that "drunk driving remains the primary threat to our families on the road."

However, she added, "this study underscores the importance of the work that MADD is doing to support people who have been victimized by drugged driving and recognize law-enforcement's efforts to pioneer effective strategies to stop drugged driving. Notably, it shows the increased danger posed by those drivers using both alcohol and drugs."

More information

For more about drugged driving, visit the U.S. National Institute on Drug Abuse.

View the original article here

Smoke and Mirrors: Driving While on Marijuana Doubles One s Chances of a Serious Car Crash

pot_driving_accident Image courtesy of iStockphoto/Cabezonication

Booze is behind an estimated 2.1 million car accidents each year in the U.S. which cause almost 11,000 traffic fatalities annually. But many drug users have claimed that a few puffs of pot before getting behind the wheel are perfectly harmless. A new study, however, shows that drivers who smoke marijuana within a few hours of hitting the road are almost twice as likely as stone-sober motorists to be in a crash that results in serious injury or death.

Authors of the new paper, published online Thursday in the British Medical Journal (BMJ), sifted through nine previous studies to develop a clearer picture of the risks to users who light up before revving up. Previous studies have left the effects of marijuana on its own when not combined with alcohol or other drugs a little hazy.

But the researchers’ findings make sense to others in the field. “Their results are consistent with experimental evidence that cannabis use leads to dose related impairments in simulated driving, psychomotor skills and on-road driving,” Wayne Hall, of the University of Queensland’s Center for Clinical Research who was not involved in the new research, wrote in a related essay in BMJ.

In addition to the finding that drivers who had recently smoked pot were substantially more likely to be involved in a serious accident, the researchers found that those who had died in these crashes had higher amounts of the drug’s compound tetrahydrocannabinol than those who survived. But there was not enough data to link concentrations of the compound to various outcomes in order to suggest a threshold for dangerous intoxication, noted the researchers, who were led by Mark Asbridge, of Dalhousie University’s Department of Community Health and Epidemiology.

Driving while stoned has become a hot topic as more states allow for medical use of marijuana. The 2009 National Survey on Drug Use and Health found that more than 10 million people admitted to having driven while on at least one illegal drug with pot being the most common. More than a dozen states currently have roadside drug tests for cannabis that sample drivers’ saliva for traces of tetrahydrocannabinol. But, as Hall noted, ascertaining a dangerous level as is currently used in a breath-based test for alcohol (0.05 percent) is less clear cut. So far many governments are using a zero-tolerance rule, but, as Hall pointed out, “researchers have proposed a concentration of tetrahydrocannabinol below which driving is not impaired.”

Assessing the definitive risk for actually being in a car crash because of marijuana use is also tricky because studies haven’t always looked at drivers who were not determined to be “at fault” or passengers of vehicles or people involved in minor accidents.

Nevertheless, Asbridge and his colleagues noted, “This information could be used as the basis for campaigns against drug impaired driving.” But the roadside testing has not been as widely publicized as rapid alcohol breath tests have been, so the chance of getting “caught” with pot in one’s system doesn’t seem to have scared very many people into not smoking before driving. As Hall wrote, the idea that roadside tests for pot will reduce traffic fatalities as drastically and as rapidly as breathalyzers did for alcohol “is probably too optimistic.” But that doesn’t mean that attempts to stub out the dangerous habit should be written off just yet. “Better evidence is essential,” Hall said of the attempts to fight pot-impaired driving with more roadside testing.

Follow Scientific American on Twitter @SciAm and @SciamBlogs. Visit ScientificAmerican.com for the latest in science, health and technology news.
© 2012 ScientificAmerican.com. All rights reserved.

View the original article here

Pot Use Could Double Risk of Car Crash, Research Shows

THURSDAY, Feb. 9 (HealthDay News) -- Getting behind the wheel within three hours after using marijuana nearly doubles a driver's risk of having an accident, a large new research review finds.

The risk is especially high for fatal crashes, and the risk is only a little less than that of people who drive drunk, Canadian researchers say.

"On the whole, alcohol increases the risk of a crash at a higher level than cannabis [marijuana]," said lead researcher Mark Asbridge, an associate professor in the community health and epidemiology department at Dalhousie University, in Halifax.

But marijuana makes it harder to judge distance and drivers often tailgate and swerve from lane to lane, which cuts down their reaction time and leads to crashes, he explained.

Although the extent of the problem isn't known, some studies have found that 5 percent of people report driving after using marijuana; and for those under age 25, as many as 20 percent, Asbridge said.

Studies on the effect of driving under the influence of marijuana have had mixed results, he said.

"There were some studies finding that cannabis actually had a negative association with crash risk, so people were actually safer using cannabis driving than when they weren't, but these were poorly designed studies," Asbridge said.

"So our study gives some clarity to the issue in showing a doubling of the risk in the very best studies that are out there and adds some level of justification to existing policies that restrict drug-impaired driving," he said.

The report was published in the Feb. 10 online edition of the BMJ.

To see how marijuana affected driving, Asbridge's team reviewed nine studies that included more than 49,000 people. This process -- called a meta-analysis -- looks for patterns across studies.

The researchers found that those driving under the influence of marijuana were nearly twice as likely to have a car crash as those who were not under the influence.

Studies outside the review have shown that drivers aged 35 and younger are more likely to have car accidents after using marijuana, the authors noted.

"These findings reaffirm many of our accepted understandings regarding acute cannabis intoxication and psychomotor performance," said Paul Armentano, deputy director of NORML (the National Organization for the Reform of Marijuana Laws). "That is why operating a motor vehicle while acutely impaired by cannabis is presently a criminal offense in all 50 states."

This risk appears to be greatest in less-experienced cannabis users, younger drivers, and among those who combine the use of cannabis and alcohol, Armentano pointed out.

"That said, it should further be noted that cannabis-induced changes in performance are typically subtle, short-lived and less dramatic in more experienced cannabis consumers, who appear to develop tolerance to some of the drug's behavioral effects," he added.

"Further, this overall elevated risk is far less than the elevated risk of accidents associated with the consumption of alcohol, including its use in legal quantities," Armentano said.

While some suggest that drivers should be tested for marijuana, so far, no effective test exists that can be done at a traffic stop to accurately pinpoint when a driver used the drug.

"This evidence makes a case for introducing policies to reduce cannabis-impaired driving," said Wayne Hall, from the University of Queensland Centre for Clinical Research in Brisbane, Australia. He wrote an accompanying editorial for the journal.

He said that roadside drug testing, such as that used for alcohol, may be a useful approach.

But there are no handy devices, such as a breathalyzer, to tell if someone has recently used marijuana, Asbridge noted.

"The challenge is defining a level that equates with impairment. A number of countries have already introduced roadside testing by deciding that any detectable evidence of recent use constitutes impaired driving. However, we do not know how effective testing has been because the policy has not been evaluated," Hall said.

Another expert outlined the problems with such tests.

"Because THC, the active ingredient in marijuana, can be detected several weeks after use of marijuana, it is hard to determine with certainty if a driver testing positive for marijuana is indeed impaired by the substance at the time of testing," said Dr. Guohua Li, a professor of epidemiology at Columbia University in New York City.

So more research is needed. "This issue is especially urgent and important in light of the ongoing epidemic of drugged driving and increased permissibility and availability of marijuana worldwide," Li said.

While recognition that driving under the influence of marijuana is a problem is a first step in finding ways to curb it, Jan Withers, national president of Mothers Against Drunk Driving (MADD), stated that "drunk driving remains the primary threat to our families on the road."

However, she added, "this study underscores the importance of the work that MADD is doing to support people who have been victimized by drugged driving and recognize law-enforcement's efforts to pioneer effective strategies to stop drugged driving. Notably, it shows the increased danger posed by those drivers using both alcohol and drugs."

More information

For more about drugged driving, visit the U.S. National Institute on Drug Abuse.

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