Scientific investigation has not found evidence for traditional Chinese concepts such as qi, meridians, and acupuncture points. [a] The TCM theory and practice are not based upon scientific knowledge, and there is disagreement between TCM practitioners on what diagnosis and treatments should be used for any given patient. The effectiveness of Chinese herbal medicine remains poorly researched and supported. There are concerns over a number of potentially toxic plants, animal parts, and mineral Chinese medicinals. There are also concerns over illegal trade and transport of endangered species including rhinoceroses and tigers, and the welfare of specially farmed animals including bears. A review of cost-effectiveness research for TCM found that studies had low levels of evidence, but so far have not shown beneficial outcomes. Pharmaceutical research has explored the potential for creating new drugs from traditional remedies, with few successful results. A Nature editorial described TCM as "fraught with pseudoscience", and said that the most obvious reason it has not delivered many cures is that the majority of its treatments have no logical mechanism of action. Proponents suggest that research has so far missed key features of the art of TCM, such as unknown interactions between various ingredients and complex interactive biological systems.