Preparing rice in a coffee machine can halve levels of the naturally occurring substance.
The substance being arsenic, and the question being "what type of coffee machine can you cook rice in?" (I'm pretty sure filling used Nespresso pods with a teaspoon of rice is not going to work, and also take a hell of a long time to serve the dinner party.)
I think I've had a post about this before - rice is particularly prone to sucking up arsenic and getting it into your diet. And it seems pretty unclear as to how dangerous it could be over a lifetime.