Robert Frichtel advocates for them:
The marijuana industry (both medical and recreational) needs to develop production standards concerning pesticides and chemicals and appropriate disclosure on the labels. Warnings should be included about driving or operating machinery and that use by those younger than 21 is illegal. The industry should also create a simple grading system that shows THC potency. It probably wouldn’t need to be as specific as the alcohol-content labels on most beverages, but perhaps based on a scale of “light,” “medium,” “heavy” and “extra heavy.” That way a consumer will be less likely to exceed his or her limit.