Cannabis that has been improperly dried may become contaminated with mold after being packaged. Even if the initial microbiological screening has been passed, improperly dried flower may contain mold and mycotoxins that grew during storage. Cannabis flower is required to be tested for total Moisture Content and water activity.
Water Activity is the amount of moisture available for microbes, a higher water activity reading means the cannabis is susceptible to
microbial growth. Results range from 0.000 to 1.000, and California mandates a value below
0.650 Aw to pass water activity testing.