While this old article (1983) has some accurate information in it, it's not the last word on copper toxicity. The labs used did seem to wash the hair prior to testing which ARL and TEI both avoid doing. Dr. Wilson says that will skew the results. Also, using drugs to chelate the copper is not something NB proposes due to pulling out other vital minerals. My zinc was quite low on the first test, and I would have hated to lose some of that due to chelation in the form they did it. It took me a long time to bring it up as it was.