It’s finally happened – the Drug Enforcement Administration (DEA) has admitted that marijuana is “clearly” safer than heroin. Though this isn’t news to science, it represents a small but significant shift in the DEA who had previously refused to acknowledge that marijuana is less dangerous than heroin.

The science has been clear on the matter for a while. Not only is marijuana safer than heroin, but drug experts broadly agree that it’s also safer than alcohol. Yet, both drugs continue to be Schedule I controlled substances. According to the DEA, marijuana and heroin “have no currently accepted medical use in the United States, a lack of accepted safety for use under medical supervision, and a high potential for abuse.”

The DEA’s acknowledgment follows a recent study released earlier this week that has challenged previous research linking teenage marijuana use with physical and mental health issues. Research on marijuana has been widely conflicted for the last few decades due to different methodologies and various factors that are difficult to control for.

In the new study, 408 men were recruited from early adolescence and followed until their 36th birthday by researchers from the University of Pittsburgh. Participants were put into four groups: low or non-users, early chronic users, those who only smoked marijuana during adolescence and participants who started using the drug as teens and continued into their adult years.

Researchers found that smoking pot as an adolescent did not cause extensive health problems later on in life. After controlling for other factors, such as cigarette smoking, socioeconomic status and drug use, researchers found no links between marijuana use and physical or mental health problems, including depression and asthma.

“What we found was a little surprising,” lead researcher Jordan Bechtold said in a statement. "There were no differences in any of the mental or physical health outcomes that we measured regardless of the amount or frequency of marijuana used during adolescence."

Researchers detailed their findings in the journal Psychology of Addictive Behaviors. Currently, marijuana is legalized in four states and is legal for medical purposes in 23 states.

DEA head Chuck Rosenberg told reporters Wednesday morning that “heroin is clearly more dangerous than marijuana.” According to The Huffington Post, Rosenberg was clarifying a previous statement he had made last week, saying marijuana is “probably not” as dangerous as heroin, though adding he was “not an expert.”

Rosenberg's statements are an obvious departure from his predecessor Michele Leonhart, who had refused to say whether heroin is worse than marijuana for someone’s health. Rosenberg was clear that he still wanted to enforce current federal marijuana laws, but also said he will be focusing on “the biggest and most important cases there are.”