The fentanyl crisis that has claimed growing numbers of lives in the United States has been showing up on the streets of Tijuana, where intravenous drug users are often unknowingly injecting the powerful synthetic drug, according to a newly released research study.

While Mexico is more commonly portrayed as both a producer and corridor for fentanyl shipments bound for the United States, the study gives a rare glimpse into a developing consumption problem — and authors are hoping public policymakers will take note.