大麻的危險性低於酒精與菸草？

For Michele Leonhart, the administrator of the Drug Enforcement Administration, there is no difference between the health effects of marijuana and those of any other illegal drug. "All illegal drugs are bad for people," she told Congress in 2012, refusing to say whether crack, methamphetamines or prescription painkillers are more addictive or physically harmful than marijuana.

在美國禁毒署署長米歇爾·萊昂哈特(Michele Leonhart)看來，大麻引起的健康問題和其他違禁藥品引起的健康問題是沒有區別的。“所有違禁藥品都對人們有害，”她在2012年的時候對國會做了上述表示，但她不願意評價精煉可卡因、冰毒或處方止痛藥是否比大麻更容易上癮、對身體的危害更大。

Her testimony neatly illustrates the vast gap between antiquated federal law enforcement policies and the clear consensus of science that marijuana is far less harmful to human health than most other banned drugs and is less dangerous than the highly addictive but perfectly legal substances known as alcohol and tobacco. Marijuana cannot lead to a fatal overdose. There is little evidence that it causes cancer. Its addictive properties, while present, are low, and the myth that it leads users to more powerful drugs has long since been disproved.

關於大麻，科學上已經有清晰的共識，認爲它對人體健康的害處遠比大多數禁藥要小，危險性也比酒精飲料和菸草等合法的高成癮性物品要低，但萊昂哈特的證詞反映出，陳舊的聯邦法規強制措施與科學共識之間有着巨大的鴻溝。過量使用大麻不會引起致命後果。幾乎沒有證據表明它能致癌。它雖然有成癮性，但極其微小，關於它會導致使用者嘗試更強烈的毒品這一神話早就被證明是假的。

That doesn’t mean marijuana is harmless; in fact, the potency of current strains may shock those who haven’t tried it for decades, particularly when ingested as food. It can produce a serious dependency, and constant use would interfere with job and school performance. It needs to be kept out of the hands of minors. But, on balance, its downsides are not reasons to impose criminal penalties on its possession, particularly not in a society that permits nicotine use and celebrates drinking.

這並不意味着大麻完全無害；事實上，當前品種的藥效可能會令幾十年沒有嘗試過它的人感到震驚，特別是作爲食物口服使用。它可以造成嚴重的依賴，持續使用會影響工作與學習表現。未成年人必須遠離它。但是總體來說，它的副作用並不足以支持對持有者施加刑事懲罰，更何況這個社會允許使用尼古丁，還讚美飲酒。

Marijuana’s negative health effects are arguments for the same strong regulation that has been effective in curbing abuse of legal substances. Science and government have learned a great deal, for example, about how to keep alcohol out of the hands of minors. Mandatory underage drinking laws and effective marketing campaigns have reduced underage alcohol use to 24.8 percent in 2011, compared with 33.4 percent in 1991. Cigarette use among high school students is at its lowest point ever, largely thanks to tobacco taxes and growing municipal smoking limits. There is already some early evidence that regulation would also help combat teen marijuana use, which fell after Colorado began broadly regulating medical marijuana in 2010.

大麻對健康的負面作用成爲對其採取強硬措施的理由，在限制濫用合法物品方面，強硬措施作用顯著。科學界與政府已經獲得不少經驗，比如說，該怎樣讓未成年人遠離酒精飲料。通過禁止法定年齡以下的人飲酒的強制性法令，以及切實有效的市場宣傳，2011年，未成年人飲酒率降低到24.8%，低於1991年的33.4%。受益於菸草稅和日漸增加的市政吸菸限制規定，中學生的菸草使用率也已達到有史以來的最低點。已有若干早期證據表明，制定相關規定有助於減少青少年對大麻的使用——2010年，科羅拉多州開始宏觀管理醫用大麻，青少年對大麻的使用率也隨之下降。

Comparing the Dangers

危險性對比

As with other recreational substances, marijuana’s health effects depend on the frequency of use, the potency and amount of marijuana consumed, and the age of the consumer. Casual use by adults poses little or no risk for healthy people. Its effects are mostly euphoric and mild, whereas alcohol turns some drinkers into barroom brawlers, domestic abusers or maniacs behind the wheel.

與其他消遣物相比，大麻對健康的影響視使用頻率、藥效、使用量，以及使用者的年齡而定。健康的成年人偶爾少量使用，是幾乎乃至完全沒有任何危險的。大麻的效果主要是令人精神愉快，變得溫和，而酒精則會令有些飲酒者在酒吧裏惹是生非，在家裏施行暴力，或者危險駕駛。

An independent scientific committee in Britain compared 20 drugs in 2010 for the harms they caused to individual users and to society as a whole through crime, family breakdown, absenteeism, and other social ills. Adding up all the damage, the panel estimated that alcohol was the most harmful drug, followed by heroin and crack cocaine. Marijuana ranked eighth, having slightly more than one-fourth the harm of alcohol.

2010年，一個英國獨立科學委員會對比了20種藥品對個體使用者的傷害，乃至對社會整體的傷害（包括導致犯罪、家庭破裂、曠工曠課，乃至其他社會問題）。將所有的傷害綜合在一起後，該小組認爲酒精是最有害的物品，海洛因與精煉可卡因緊隨其後。大麻位列第八，傷害性約相當於酒精的1/4多一點。

Federal scientists say that the damage caused by alcohol and tobacco is higher because they are legally available; if marijuana were legally and easily obtainable, they say, the number of people suffering harm would rise. However, a 1995 study for the World Health Organization concluded that even if usage of marijuana increased to the levels of alcohol and tobacco, it would be unlikely to produce public health effects approaching those of alcohol and tobacco in Western societies.

聯邦政府的科學家說，酒精與菸草帶來的傷害較高，主要是因爲它們可以合法獲取，因此他們認爲，如果大麻也合法化、可以輕鬆獲取的話，那麼受到傷害的人數也會增加。然而，1995年，世界衛生組織的一項研究推斷，即便大麻的使用率增長到和酒精與菸草同樣的水平，它在西方社會所引發的公共健康問題也不太可能達到酒精與菸草的程度。

Most of the risks of marijuana use are "small to moderate in size," the study said. "In aggregate, they are unlikely to produce public health problems comparable in scale to those currently produced by alcohol and tobacco."

這項研究聲稱，使用大麻所帶來的大部分危險在等級上處於“很小或中等程度”。“總體而言，它導致的公共健康問題不太可能達到目前菸草與酒精所導致的這種規模。”

While tobacco causes cancer, and alcohol abuse can lead to cirrhosis, no clear causal connection between marijuana and a deadly disease has been made. Experts at the National Institute on Drug Abuse, the scientific arm of the federal anti-drug campaign, published a review of the adverse health effects of marijuana in June that pointed to a few disease risks but was remarkably frank in acknowledging widespread uncertainties. Though the authors believed that legalization would expose more people to health hazards, they said the link to lung cancer is "unclear," and that it is lower than the risk of smoking tobacco.

吸菸會導致癌症，酗酒則會導致肝硬化，而大麻與任何致死疾病之間都沒有清晰的因果聯繫。國家藥物濫用研究所的專家們是聯邦反毒品行動中的科學力量，他們於6月發佈了一份關於大麻對健康損害的報告，指出大麻有若干致病風險，但它也非常坦白地承認，這些風險存在着不確定性。儘管報告作者們相信，大麻合法化會使得更多人蒙受健康風險，但報告也說大麻與肺癌之間的關係“不明確”，而且吸大麻比吸菸的風險要低。

The very heaviest users can experience symptoms of bronchitis, such as wheezing and coughing, but moderate smoking poses little risk. A 2012 study found that smoking a joint a day for seven years was not associated with adverse effects on pulmonary function. Experts say that marijuana increases the heart rate and the volume of blood pumped by the heart, but that poses a risk mostly to older users who already have cardiac or other health problems.

最爲頻繁的大麻使用者會有支氣管炎的症狀，比如氣喘和咳嗽，但一般用量的使用者風險很小。一項2012年的研究表明，連續七年每日吸一支大麻捲菸不會引起肺功能損害。專家說大麻會加快心率，以及心臟的供血量，但這主要是對已經患有心臟病和其他健康問題的老年使用者有風險。

How Addictive Is Marijuana?

大麻的成癮性有多高？

Marijuana isn’t addictive in the same sense as heroin, from which withdrawal is an agonizing, physical ordeal. But it can interact with pleasure centers in the brain and can create a strong sense of psychological dependence that addiction experts say can be very difficult to break. Heavy users may find they need to take larger and larger doses to get the effects they want. When they try to stop, some get withdrawal symptoms such as irritability, sleeping difficulties and anxiety that are usually described as relatively mild.

大麻的成癮性與海洛因完全不能相提並論。戒除海洛因非常痛苦，是對身體的嚴峻考驗。但是大麻可以與大腦中的快樂神經中樞互動，產生強烈的精神依賴，藥物成癮專家說這種聯繫很難消除。重度使用者可能會需要更大的劑量，才能達到自己想要的效果。想要停止使用時，會出現易怒、睡眠障礙和焦慮等戒斷症狀，這些症狀通常被描述爲相對輕微。

The American Society of Addiction Medicine, the largest association of physicians specializing in addiction, issued a white paper in 2012 opposing legalization because "marijuana is not a safe and harmless substance" and marijuana addiction "is a significant health problem."

美國成癮藥物協會是最大的專攻成癮藥物的醫生組織，2012年，它發表了一份白皮書，反對大麻合法化，因爲“大麻不是一種安全無害的物品”，而且大麻成癮“是嚴重的健康問題”。

Nonetheless, that health problem is far less significant than for other substances, legal and illegal. The Institute of Medicine, the health arm of the National Academy of Sciences, said in a 1999 study that 32 percent of tobacco users become dependent, as do 23 percent of heroin users, 17 percent of cocaine users, and 15 percent of alcohol drinkers. But only 9 percent of marijuana users develop a dependence.

不管怎樣，這種健康問題遠比其他合法或不合法物品所帶來的健康問題要輕微得多。藥學研究中心是國家科學院的健康分部，它在1999年的一份研究報告中說，32%的吸菸者會上癮，23%的海洛因使用者會上癮，17%的可卡因使用者會上癮，15%的飲酒者會上癮，但只有9%的大麻使用者會上癮。

"Although few marijuana users develop dependence, some do," according to the study. "But they appear to be less likely to do so than users of other drugs (including alcohol and nicotine), and marijuana dependence appears to be less severe than dependence on other drugs."

“大麻上癮者人數很少，但確實有人會上癮，”這項研究說，“但是和使用其他藥品（包括酒精與尼古丁）相比，大麻的成癮率很低。”

There’s no need to ban a substance that has less than a third of the addictive potential of cigarettes, but state governments can discourage heavy use through taxes and education campaigns and help provide treatment for those who wish to quit.

完全沒有必要禁止一種成癮率不到香菸1/3的東西，但各州政府可以通過徵收重稅和教育來防止人們大量使用大麻，並對需要戒斷的人提供治療。

Impact on Young People

對年輕人的影響

One of the favorite arguments of legalization opponents is that marijuana is the pathway to more dangerous drugs. But a wide variety of researchers have found no causal factor pushing users up the ladder of harm. While 111 million Americans have tried marijuana, only a third of that number have tried cocaine, and only 4 percent heroin. People who try marijuana are more likely than the general population to try other drugs, but that doesn’t mean marijuana prompted them to do so.

反對大麻合法化的人最常用的論據之一，就是大麻會導致使用者嘗試更危險的毒品。但各種廣泛研究證明，大麻與使用者升級使用更危險的物品之間不存在因果關係。1.11億美國人都曾嘗試使用大麻，嘗試使用可卡因的人只有該數字的1/3，嘗試使用海洛因的人只相當於這個數字的4%。在使用大麻的人羣中，嘗試其他毒品的人數比例要比普通人羣爲高，但並不是大麻導致了此行爲。

Marijuana “does not appear to be a gateway drug to the extent that it is the cause or even that it is the most significant predictor of serious drug abuse,” the Institute of Medicine study said. The real gateway drugs are tobacco and alcohol, which young people turn to first before trying marijuana.

藥學研究中心的報告說，大麻“並不是一種入門藥物，並不是藥物嚴重濫用的原因，甚至也不是藥物嚴重濫用的重要預示因素”。真正的入門藥物是菸草和酒精，年輕人早在嘗試大麻之前就已經接觸到它們了。

It’s clear, though, that marijuana is now far too easy for minors to obtain, which remains a significant problem. The brain undergoes active development until about age 21, and there is evidence that young people are more vulnerable to the adverse effects of marijuana.

不過，對於未成年人來說，如今獲取大麻顯然非常容易，這仍然是個嚴重的問題。大腦發育活動要持續到21歲，有證據表明年輕人更容易受大麻副作用影響。

A long-term study based in New Zealand, published in 2012, found that people who began smoking heavily in their teens and continued into adulthood lost an average of eight I.Q. points by age 38 that could not be fully restored. A Canadian study published in 2002 also found an I.Q. loss among heavy school-age users who smoked at least five joints a week.

2012年，一項新西蘭的長期研究表明，從十幾歲開始大量使用大麻，並在成年期持續使用大麻的人到38歲時智商會下降8分，無法完全恢復。另一項加拿大於2002年發佈的研究表明，學齡期大量使用大麻（每週至少吸五支大麻煙卷）會導致智商下降。

The case is not completely settled. The New Zealand study was challenged by a Norwegian researcher who said socio-economic factors may have played a role in the I.Q. loss. But the recent review by experts at the National Institute on Drug Abuse concluded that adults who smoked heavily in adolescence had impaired neural connections that interfered with the functioning of their brains. Early and frequent marijuana use has also been associated with poor grades, apathy and dropping out of school, but it is unclear whether consumption triggered the poor grades.

這項結論並未完全定案。新西蘭的研究受到挪威一個研究者的質疑，他聲稱社會經濟因素也可能導致智商下降。但國家藥物濫用研究所最近的專家報告認爲，從青春期就大量使用大麻的人的神經連接會受到損害，從而影響大腦功能。過早經常使用大麻也與成績不佳、缺乏興趣和輟學有關，但成績不佳是否由使用大麻導致，目前尚不明確。

Restricting marijuana to adults is more important now that Colorado merchants are selling THC, the drug’s active ingredient, in candy bars, cookies and other edible forms likely to appeal to minors. Experience in Colorado has shown that people can quickly ingest large amounts of THC that way, which can produce frightening hallucinations.

目前，更重要的是把大麻的使用侷限在成年人範圍之內，科羅拉多州商人正在販賣摻入四氫大麻酚（這是大麻的活性成分，簡稱THC）的糖果、餅乾，以及其他可食用物品，這對未成年人來說可能很有吸引力。科羅拉多的經驗表明人們可以通過食用途徑，迅速吸收大量THC，這有可能導致可怕的幻覺。

Although marijuana use had been declining among high school students for more than a decade, in recent years it has started to climb, in contrast to continuing declines in cigarette smoking and alcohol use. Marijuana was found -- alone or in combination with other drugs -- in more than 455,000 patients visiting emergency rooms in 2011. Nearly 70 percent of the teenagers in residential substance-abuse programs run by Phoenix House, which operates drug and alcohol treatment centers in 10 states, listed marijuana as their primary problem.

儘管十年多以來，大麻在高中生中的使用率已經下降，但近年又開始出現攀升，與此同時，吸菸和喝酒的比例一直在下降。2011年，有45.5萬名急診病人被發現使用大麻（以及其他藥品）。“鳳凰屋”(Phoenix House)在10個州中經營着毒品與酗酒治療中心，在它所主辦的家庭反濫用毒品計劃中，近70%的受助青少年將大麻列爲自己最初的問題。

Those are challenges for regulators in any state that chooses to legalize marijuana. But they are familiar challenges, and they will become easier for governments to deal with once more of them bring legal marijuana under tight regulation.

這些都是選擇將大麻合法化的各州管理者所面臨的挑戰。但這都是一些熟悉的挑戰，各州政府一旦將合法化的大麻置於嚴格管理之下，問題就會變得容易應付得多。