Doctors in Saskatchewan are calling on the province to establish 21 as the legal age to buy recreational marijuana when legalization hits.

A resolution recommending the legal of 21 was passed by physicians at the Saskatchewan Medical Association’s spring assembly.

“Physicians have long been concerned about the harmful effects of marijuana on an individual’s health, particularly youth,” SMA president Dr. Joanne Sivertson said in a news release sent Tuesday. “Evidence shows that prolonged use of marijuana in young people can have a negative effect on a developing brain, which develops into the mid-20s.”

The association notes, while federal legislation proposes a legal of 19, provincial governments can establish their own minimum ages.

The Canadian Medical Association, the Saskatchewan branches of the Canadian Cancer Society and the Lung Association also recommend a legal age of 21, according to the SMA.

“From a medical perspective in terms of brain development, there is some merit in setting a minimum age of at least 25, but balancing the fact that recreational marijuana is coming with the need to prevent illicit sales to youths, a minimum age of 21 is a compromise,” Sivertson said.

Seven provinces have announced their legal age to buy recreational marijuana will be 19, while Alberta and Quebec have said 18 will be their minimum age.

Saskatchewan has yet to announce its legal age.