Unless you’re purchasing your cannabis in a legal state with strict lab testing requirements, there is a chance your weed could be contaminated. It is worth noting, however, that the cannabis sold in dispensaries may just have been lab tested for cannabinoid and terpene content and not contaminants. So just because a product in a dispensary has a lab testing label on it doesn’t mean it is completely safe. It’s important to read the label to see if the product was tested for safety and not just potency. Contamination can happen while growing, harvesting, handling, extracting, or storing cannabis. Some contaminations like mold or mildew can be spotted but many others require a chemical analysis.