Colorado health officials are trying to find a way to prevent people from overdosing on marijuana edibles. The products have been implicated in two suicides and one murder in the past 13 months, according to The Denver Post.

Almost five million edibles were sold in Colorado stores last year. The Denver Post commissioned lab tests of 10 popular brands, and found edibles’ highs are more delayed and long-lasting than smoking or vaporizing marijuana. Some brands severely mismeasure the potency of their products, the newspaper found.

“There’s a learning curve for consumers of edibles,” Art Way, Colorado’s state director of the pro-legalization group Drug Policy Alliance, told the newspaper. “We cannot escape the issue of personal responsibility. That said, the industry should do all that is reasonable in the formative years of marijuana legalization to combat concerns around edibles.”

The state has standardized edibles’ warning labels, and mandated that 10-milligram doses of THC, the psychoactive ingredient in marijuana, be individually wrapped. Colorado is also running educational campaigns about proper use of edibles. A mandatory lab-testing program requires edible companies to test each batch for potency.

New rules for edibles are due January 1. While they may help reduce accidental ingestions, it is unclear if they will stop people from eating too much, too fast, critics contend.

Edible marijuana products have become a popular alternative to smoking marijuana in Colorado, since retail sales of the products became legal. Adults 21 and over can legally purchase marijuana edibles at state-licensed stores. Marijuana is now available in products ranging from candy to soda and granola. The amount of marijuana in edible products varies widely. In some cases, products contain levels so high that people experience extreme paranoia and anxiety.