Neither specimen had been bleached or permed. Although it would have been ideal to use hair close to the scalp, there was no way to obtain enough of it to create 26 specimens per subject. In 1984, a Food and Drug Administration laboratory ran tests on hair specimens taken 3 and 9 inches from the scalp and prepared similarly to mine, and found that this method can produce homogeneous samples.1 Moreover, the reported values for specimen pairs I sent to each laboratory were generally much closer to each other than to those of the other laboratories. For these reasons, I believe that the variations reported in my study were caused by differences in laboratory techniques and standards rather than the way the specimens were prepared. Two investigations in which paired nape-hair specimens were sent to three laboratories have reported findings similar to mine.2,3Although Dr Walsh
Barrett S. Commercial Hair Analysis: Science or Scam?-Reply. JAMA. 1986;255(19):2604. doi:10.1001/jama.1986.03370190087024
Customize your JAMA Network experience by selecting one or more topics from the list below.