I'm certainly not an expert, but the Wikipedia article covers this as well: > it is unusual for a prion disease to transmit from one species to another. So I

I'm certainly not an expert, but the Wikipedia article covers this as well: > it is unusual for a prion disease to transmit from one species to another. So I'd expect the risk to be higher when dealing with human remains. There is a notable exception to this general rule: > Creutzfeldt–Jakob disease, however, is thought to be caused by a prion that typically infects cattle, causing bovine spongiform encephalopathy and is transmitted through infected meat The other problem (mentioned by another poster) is that just because someone didn't die of a prion disease doesn't mean they aren't harboring prions because the incubation period is 5 - 20 years. General comment: the risk may very well end up being low, but I would personally prefer to avoid consuming plants that were grown on composted human brain or spinal material to lower my personal risk.