I don't think that is the case: I don't think any imported oxymatrine sources have been analyzed. So we don't actually know whether there are any contaminants in this oxymatrine imported from China. It's just speculation. Sure, some Chinese herbs have in general been found to have higher levels of contaminants, but this study on imported Chinese herbs says that "the vast majority (95%) of the 334 samples in this study contained levels of heavy metals or pesticides that would be of negligible concern." So the chances are that imported oxymatrine supplements are perfectly safe. I believe Chia sometimes prescribes this imported oxymatrine to his patients instead of Equilibrant, so Chia presumably thinks that the imported oxymatrine is most likely safe.