What is the fine-grained topic of the following text: After her fellowship, Mackenzie wrote: "The various opportunities that I had to actually meet, talk to and interact with the waste pickers in their communities were the best for me—this was the most real, the most valuable in terms of information gathered [not just data, but the chance to make observations about sights, smells, emotions, etc, involved with their lives that helped me to understand their points of view and experience]." Only return the topic.
Mackenzie's interaction with waste pickers during her fellowship