Hurley, Dan, (Broadway Books, 2006) The word "natural" in the title refers to illness and death caused by use of natural products. In the USA, one can put anything in a bottle (without evidence for safety and efficacy, or purity), call it a "dietary supplement," append a vague claim (such as supports immunity) and sell it with impunity. However, the book describes the general problems of using herbs that are not regulated as strictly as pharmaceuticals. For example, an herb (stephania) in Belgium was found to be contaminated with aristolochia in 1993. Aristolochia caused kidney failure, and then kidney cancer, the same problem was found shortly thereafter in the USA.