(CNN) — (CNN) -- Marijuana use is holding steady among eighth, 10th- and 12th-graders in the United States and tobacco smoking rates remain low.
Those are some of the results published in the annual Monitoring the Future study, a survey of more than 45,000 8th, 10th, and 12th graders from 395 public and private schools. It was released Wednesday.
Each year, the survey gathers information from teens about their use of alcohol, drugs, and tobacco, as well as asking them questions regarding their attitudes about the drugs.
This year, 6.5% of 12th-graders said they smoke marijuana daily. That's slightly down from 2011, when 6.6% said they smoked it daily.
Teens' perception about the harmfulness of using marijuana was down, which may signal future increases in marijuana use, according to the study's principal investigator, Lloyd Johnston.
Overall, 41.7% of eighth-graders perceive occasional marijuana use as harmful and 66.9% see regular use as harmful. As teens get older, their perception of harm decreases, the survey showed, with only 20.6% of 12th-graders seeing regular use as harmful.
"Marijuana use that begins in adolescence increases the risk they will become addicted to the drug," says Dr. Nora Volkow, director of the National Institute on Drug Abuse, in a statement. "The risk of addiction goes from about 1 in 11 overall to about 1 in 6 for those who start using in their teens, and even higher among daily smokers."
New this year were questions about "bath salts," products that contain designer drugs with stimulant effects. Very few students reported having used bath salts in the previous twelve months: 0.8%, 0.6%, and 1.3% for grades eight, 10, and 12, respectively.
The use of synthetic marijuana products remained stable, with 11.3% of 12th-graders reporting having used them. Other than alcohol and tobacco, this is the second most widely used drug among 10th- and 12th-graders after marijuana. The products are generally sold on the Internet or over the counter, with names such as K-2 and spice. They are produced by spraying herbs or plant materials with the chemical elements found in marijuana.
Use of other illicit drugs showed no significant change between 2011 and 2012. Those drugs include cocaine, crack, heroin, hallucinogens, amphetamines, sedatives, tranquilizers or narcotics taken without medical supervision. Only salvia, ecstacy and using heroin without a needle showed significant declines.
Adderall is one drug that showed some sign of increasing, but only among 12th graders, and not very significantly. Its use increased 1.1% from 2011 to 2012.
Alcohol use, which declined in 2011, showed an increase among 12th-graders. Twenty-four percent of high school seniors reported binge drinking two weeks prior to the survey, an increase of 2%.
"The nation's teenage drug problems are far from disappearing," concluded Johnston. He noted that new drugs are appearing on the horizon, products that include synthetic marijuana and "bath salts."
According to Johnson "synthetic drugs like these are particularly dangerous, because they have unknown, untested, and ever-changing ingredients that can be unusually powerful, leading to severe consequences. Users really don't know what they are getting, and as the thousands of calls to the nations's poison control centers relating to these drugs indicate, they may be in for a very unpleasant surprise."
The Monitoring the Future survey was sponsored by NIDA and the University of Michigan, which designed and conducted the study.