Rick Bowmer, File, Associated Press
This March 28, 2011 photo shows a marijuana plant, in Portland, Ore.

Following in the footsteps of Colorado and Washington, where voters legalized the recreational use of marijuana in last year’s election, four other states — California, Alaska, Oregon and Arizona — have similar measures on the ballot this year.

That may be an inevitable consequence of the federal government indicating it will stand aside and allow such laws, even though they run afoul of federal laws. But Americans need to think twice before jumping on this bandwagon.

Marijuana is a harmful drug. That much is beyond dispute, no matter what the drug’s advocates say. It is particularly harmful to young people who begin smoking it regularly, but it also is harmful to adults. It is addictive.

And while legalization advocates opened the door with laws in many states allowing for the medicinal use of the drug, the federal government reports there still have not been enough clinic trials to demonstrate that its benefit outweigh the risks; nor is it a medicine in the sense that it can be measured and consistently ingested in a dosage that could be prescribed. Plenty of anecdotal evidence suggests those laws are being exploited by people who simply want to get high.

In addition, the movement toward legalization, or at least relaxed enforcement, has not reduced the violence associated with its cultivation and production. A recent story in The Press Democrat in Santa Rosa, Calif., said that state’s marijuana growing market was estimated at $14 billion in 2010 and that homicides connected to that industry are common.

The paper quoted Mendocino County Sheriff Tom Allman saying the killings are related to sales, the business side of cultivation and money.

Legalization proponents often say violence will disappear once marijuana is legal and the illicit profit motive is gone. But those arguments always have been specious. Northern California apparently has become a center for growing and illegally importing the drug to other parts of the globe. Even if the drug is legalized and controlled for quality everywhere, growers would seek to find ways to make more potent varieties that would enjoy lucrative underground markets.

Proponents also are fond of saying marijuana is no worse than alcohol. We wonder what part of alcohol’s enormous cost to society they feel makes it worth the official stamp of government approval — the roughly 10,000 annual drunk-driving deaths; the loses in productivity and wages; the family dissolutions; the health problems?

Perhaps the greatest danger of the gradual acceptance of marijuana nationwide is that the lies of its proponents are taking root in a younger generation. Nora D. Volkow, director of the National Institute on Drug Abuse, wrote on the organization’s web site that she encounters “growing skepticism about marijuana’s dangers” in the questions she receives from high school students. Many of them believe the drug is safe, non-addictive and even healthy.

The evidence tells a different story. It is addictive, it increases heart-attack risks, affects judgment and motor ability, and is particularly brutal on cognitive abilities such as memory and learning when used over a long period of time.

Volkow writes that the drug “sets the user on a downward life trajectory, one that is driven by a constellation of factors that include altered cognitive and social development.”

Why would anyone feel a compelling need to make such a thing legal and socially acceptable, no matter how many people already use it?