NAS conclusions about CANNABIS EDIBLES:

Edibles make it harder to titrate the intoxicating effects due to the delayed and variable onset. Consequently, edibles have been tied to the ingestion of excessive amounts of cannabis under the misperception that the initial dose had not produced the desired effect. The availability of edibles has also been associated with increased rates of accidental pediatric ingestion of cannabis.

Meanwhile, the increasing availability, diversity, and potency of cannabis products create the potential for an increased risk of adverse health effects related to cannabis use, including overdose injury and death. Accidental ingestion of high-potency cannabis products by young children can result in respiratory failure and coma, as noted by several case reports. Cannabis edibles were identified as a contributing to acute psychosis and death of a teen who jumped off a building.

For full report, see:
http://nationalacademies.org/CannabisHealthEffects