Meth once had a variety of adulterants and contaminants that lowered the purity. Meth that’s made in small backyard labs is more likely to come out with impurities. According to the DEA, Meth that comes from Mexican cartels is often made in super labs that produce high-purity meth, which can be extremely powerful. Forbes reported on DEA data about the purity of illicit drugs throughout the United States. Other drugs were much less pure. Heroin may be found with 20 to 60% purity, and cocaine may be found at 40 to 70% purity. The lowest purity meth was found in Wyoming at 74.3%, and the highest purity was found in Arizona at 97.5%.High-purity drugs are often found closer to the Southwest border of the United States. However, there is no guarantee that the meth you come across is high or low purity. The nature of the illicit drug market is that it produces unregulated and unpredictable products.