Are new laws leading more teens to smoke marijuana?

A survey shows American teenagers abuse prescription and hard drugs less often than they used to, but they seem to be viewing marijuana use with decreasing wariness even as state governments legalize the drug for adult use.

Marijuana use is becoming more acceptable to Americans in general – and that includes teenagers.

The shift was highlighted in a 2015 "Monitoring the Future" survey, which found teen use of pot has held steady in the last year even as abuse of most other drugs has declined among teens. At the same time, the survey indicates, teens are showing less concern about the dangers of marijuana use. The survey, published Wednesday by the National Institutes of Health, was conducted by researchers at the University of Michigan.

"We are heartened to see that most illicit drug use is not increasing, non-medical use of prescription opioids is decreasing, and there is improvement in alcohol and cigarette use rates," said Dr. Nora Volkow, director of the NIH's Institute of Drug Abuse, in a press release. "However, continued areas of concern are the high rate of daily marijuana smoking seen among high school students, because of marijuana’s potential deleterious effects on the developing brains of teenagers."

Teens are laying off the "hard drugs," such as heroin and ecstasy at encouraging rates, and abuse of prescription drugs designed to treat pain has declined from 10.5 percent in 2003 to 4.4 percent, according to the survey.

But while use of most drugs declined, teens kept using pot at a stable rate. Even more significantly, the survey found a shift in how teenagers view marijuana use.

Fewer teens reported they thought using weed was risky – 31.9 percent versus 36.1 percent in 2014, and 6 percent of twelfth graders smoke daily. This is in contrast to smoking tobacco, which teenagers now view with caution at increasingly high rates. Three-quarters of high school seniors said smoking a pack of cigarettes per day was harmful.

This shift in how risky teens think marijuana is occurring as more states debate further legalized marijuana use among adults. Four states have legalized marijuana completely, but 23 have legalized it with some restrictions. Teens may be taking their cue from state legislators who feel the drug is not "risky" enough to ban.

Increased acceptance is being seen on the the federal side as well, as President Obama noted a trend toward legalization in an interview with Vice News.

"You're starting to see not just liberal Democrats, but also some very conservative Republicans recognize [prohibition] doesn't make sense, including sort of the libertarian wing of the Republican Party," he told Vice News in April.

The decline of most drug use and smoking among teens may show that educating teenagers about the hazards of drugs can impact their behavior. But if the message is mixed – as it is when states legalize the drug for broader and broader use among adults while still telling teens to avoid it – the results of drug prevention programs could be mixed as well.

With more state legislatures poised to legalize marijuana, statistics describing the impact shifts at the legislative level can have on teenage behavior are all the more significant.