A new study has found that teenagers in California consistently perceive cannabis as less harmful than alcohol, nicotine vapes, and cigarettes. The research is based on an analysis of two large school surveys involving more than 175,000 students. The study was conducted by scientists from the University of California, San Diego, led by Professor Shu-Hua Zhu, and the results were published in the journal Drug and Alcohol Dependence.

An analysis of data from 2019–2020 and 2024 showed a stable trend: cannabis is perceived by adolescents as the least dangerous of commonly used psychoactive substances. In the first survey, about two-thirds of teenagers considered regular cannabis use harmful, while alcohol, tobacco, and vaping products were rated as more dangerous. For occasional use, perceived risk decreased for all substances, but cannabis still remained “the safest” in the eyes of adolescents.

Importantly, this pattern remained virtually unchanged several years later — in the 2024 data, researchers observed the same hierarchy of risk perception.

Researchers also examined the factors influencing these perceptions. They found that as teenagers get older, they tend to see cannabis as even less dangerous: younger students are more likely to view it as harmful, while by 12th grade, concern significantly decreases. For alcohol and tobacco, the trend was either stable or reversed.

Another important factor is personal experience. Teenagers who had already tried certain substances were significantly less likely to consider them harmful.

Social environment also had a strong influence. The more friends used a given substance, the lower teenagers rated its harm. This effect was especially pronounced for cannabis, highlighting the role of normalization of its use within adolescent peer groups.

The authors of the study warn that low risk perception is an important factor associated with a higher likelihood of use. Although overall teenage cannabis use has declined in recent years, it remains a concern for experts due to its potential impact on brain development, cognitive function, and mental health.