1) Where does fentanyl come from? Let's take a trip to Guadalajara, Jalisco, where Mexican customs, la Guardia Nacional, & federal prosecutors seized just seized 121 pounds of fentanyl during a customs inspection from China--most of this fentanyl would be destined for the U.S. https://twitter.com/AlexBerenson/status/1336333548773539845

2) drug market. Much of the fentanyl that arrives from China will be made into pill form in crude drug labs in Mexico, then smuggled into the United States. These fentanyl pills are totally unpredictable since there is no quality control conducted when being manufactured in drug

3) labs across Mexico. Based on a sampling of tablets seized nationwide between January & March 2019, DEA found that 27% contained potentially lethal doses of fentanyl. A lethal dose of fentanyl is estimated to be about 2 milligrams but can vary based on an individual’s body size

4) tolerance, amount of previous usage & other factors. In November of 2019, DEA issued a warning: Mexican drug cartels are manufacturing mass quantities of counterfeit prescription pills containing fentanyl, a dangerous synthetic opioid that is lethal in minute doses.

https://diariotijuana.info/aduanas-y-guardia-nacional-impiden-ingreso-de-55-kilos-de-fentanilo-en-la-aduana-de-guadalajara-en-coordinacion-con-fgr/