After the discussions of the large amounts of fentanyl being confiscated lately, here's an article from the cdc discussing methods of dissemination (water).

https:// www.cdc.gov/niosh/ershdb/emergencyresponsecard_29750022.html

Also, here's another article discussing how "fentanyl has been tested as chemical weapon by military for decades".

https:// www.cdc.gov/niosh/ershdb/emergencyresponsecard_29750022.html

Haven't seen it posted, thought it might be important.