Any drug can be a problem with kids in the house.

When I was in 6th grade, a trusted adult member of my family gave me some medication prescribed for an adult to "calm me down" over a period of several weeks. This was the beginning of a 3-year barbituate habit. The adult didn't continue to give it to me, but I knew where it was: in the medicine cabinet, between the aspirin and the antacid. In retrospect, that was much more dangerous than any pot habit I could have had.

On the other hand, people who smoke cigarettes can effectively limit their children's exposure to second-hand smoke by smoking outdoors only, or smoking only in a single area of the house which is equipped with air filters. Smoke from any source can be handled the same way.

Children can be kept safe from any drug in the house by responsible adults. Children can be endangered by inappropriate behavior by adults in many, many ways.

Re: your observation that a person being medicated with canniboids must not have children in the house, I would suggest that, if this were the case, children should be removed from the house when cocktail parties or other events where adults are consuming more than a serving of alcohol are in progress. In the case of some families, that would mean every televised football game. (In my case, it would mean the Kentucky Derby: 2 killer mint juleps, followed by very weird croquet.)

The little high from medical marijuana isn't the same as Cheech and Chong stoned, any more than the buzz from two beers equals falling-down drunk. To single this drug out is part of the continuing saga of Prohibition: why teach and enforce responsibility when we can merely forbid select use and believe the problem is thus banished?