A sweeping Associated Press investigation into prison labor in the United States found that prisoners who are hurt or killed on the job are often being denied the rights and protections offered to other American workers.

These prisoners are being placed in dangerous jobs, sometimes with little or no training. They pick up trash along busy highways, fight wildfires, and operate heavy machinery. They work on industrial-sized farms and meat-processing plants tied to the supply chains of some of the world’s most iconic brands and companies. But incarcerated workers and their families often have little or no recourse when things go wrong.

The report on the dangers of prison labor is part of a wider AP investigation into what has become a multibillion-dollar industry that often operates with little oversight.

Here are takeaways from the latest installment of AP’s investigation: