Using lessons learned from alcohol and tobacco regulation can help keep legalized marijuana out of children’s hands, according to experts at the Bloomberg School of Public Health at Johns Hopkins University.

Laws legalizing recreational marijuana have been passed in Colorado, Washington, Oregon, Alaska* and Washington, D.C. While all of the current laws make marijuana use legal only for those over the age of 21, the researchers say the laws normalize marijuana use, and can put the drug more easily into the hands of young people. The experts note it is more difficult to regulate marijuana than alcohol or tobacco, because people can grow it at home.

Brendan Saloner, PhD and colleagues suggest four strategies to prevent marijuana use among minors. These include using tax policies to keep prices high, News-Medical.net reports. “Research has shown that young people are particularly price sensitive and tend to reduce cigarette use at higher rates than adults after price increases,” commentary co-author Beth McGinty, PhD noted in a news release.

Retail availability of marijuana should be tightly regulated, the public health experts write in Pediatrics. States should more strongly enforce existing laws, including more compliance audits and tougher penalties. States should keep marijuana away from playgrounds and schools, and prohibit stores that sell other products from also selling marijuana, they advise.

To prevent the accidental ingestion of marijuana by children, states should regulate the appearance of foods containing the drug, and reduce the amount of THC, the main psychoactive ingredient, allowed in these foods. They also recommend childproof packaging and clear labeling for these products.

The article notes that Washington state enacted emergency rules banning images of cartoons, toys and other pictures that appeal to young children on foods containing marijuana. Colorado regulates child-safe packaging of marijuana products.

The experts also suggest restricting marketing of marijuana products.

*CORRECTION: Alaska has legalized recreational marijuana, and not Arizona.