In addition to being commonly added to heroin, fentanyl can be purchased directly from China through the Dark Web. 2 milligrams of pure fentanyl is fatal.<ref>https://www.npr.org/sections/health-shots/2019/09/04/757089868/fentanyl-as-a-dark-web-profit-center-from-chinese-labs-to-u-s-streets</ref> | In addition to being commonly added to heroin, fentanyl can be purchased directly from China through the Dark Web. 2 milligrams of pure fentanyl is fatal.<ref>https://www.npr.org/sections/health-shots/2019/09/04/757089868/fentanyl-as-a-dark-web-profit-center-from-chinese-labs-to-u-s-streets</ref> |