What did the find? Apparently a bunch of different things including (but not limited to): Arsenic, cadmium, lead, dexamethasone, ephedrine, cyproheptadine, paracetamol and snow leopard DNA.
Good, but less science-y article here: https://theconversation.com/whats-in-your-herbal-medicines-52144
Science-y (methods and everything) article here: http://www.nature.com/articles/srep17475