Colorado's experiment with legalising marijuana is being threatened by the popularity of eating it instead of smoking it, leading the pot industry to join health officials and state regulators to try to curb the problem of consumers ingesting too much weed.

A task force is looking into ways to educate consumers, including a standard warning system on popular edibles, which is the industry term for marijuana that has been concentrated and infused into food or drink.

One idea was to fashion labels on edible pot similar to the difficulty guidelines on ski slopes, a system very familiar to Colorado residents. Weak marijuana products would have green dots, grading up to black diamonds for the most potent edibles.