Each year, critic Linda Holmes looks back on the year and compiles a list of the things that brought her joy.

Kratom and 7-OH products are available in many smoke shops. But earlier this year, the FDA recommended certain 7-OH products be scheduled alongside opioids. This isn’t the first time kratom has come under scrutiny. Nearly a decade ago, the DEA wanted to make certain active ingredients in kratom controlled substances. Meaning products would go from being widely available to highly restricted. After a massive wave of protest, the DEA decided not to move forward. Producer Rachel Carlson joins host Emily Kwong to talk about what could happen this time around, and what scientists know – and don’t know – about kratom and 7-OH. Interested in more of the science behind drugs and supplements? Email us your question at shortwave@npr.org.Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.