Cutler, in his book on hair tests, indicates he thinks copper in a hair test is usually relevant. However, if the hair test has statistically strange patterns--almost all essential elements low or lo-norm, etc--then he was less inclined to trust a hair test. He then suspected the presence of a toxin, especially mercury. He liked RBC test better. There might be something available in the googlebooks version. https://books.google.com/books?id=U765adeBPlEC&printsec=frontcover&dq=cutler+hair+test&cd=1&hl=en#v=onepage&q=copper&f=false