Response to comments on “Morphological changes in human head hair subjected to various drug testing decontamination strategies” by Hill et al.
We would like to thank Ms. Hill and her colleagues at Psychemedics Corporation for their valuable comments and the opportunity to clarify both the purpose of our study and selected issues. Before addressing the issues, we would like to clarify that the hair locks used in our studies reported in the Journal of Analytical Toxicology  and in Forensic Science International  were from the same sources.
Hill et al. remarked that we did not include micrographs of all five hair types in the original publication. We did this in the interest of conserving space in the article. We have included representative micrographs at 1000× of all five hair samples prior to any treatment with this reply. As previously stated and as can be seen here, the five hair samples prior to decontamination treatments were very similar in appearance.
In our evaluation of the effects of the decontamination protocols on hair, we chose at random 10 hair strands from each of the hair types for each of the protocols. The individual hairs were mounted on carbon adhesive on the stage stubs to allow observation of the mid-shaft regions. For hair types 1, 2 and 4, we observed that one hair strand out of the 10 was broken as depicted in Figure 7. In our sampling, we observed breaks like this only in strands decontaminated using aqueous buffer. Hair locks from these groups decontaminated with aqueous buffers were noticeably more brittle when handled. All hair strands observed from the aqueous buffer treatment exhibited the appearance of degrading scales as shown in Figures 5 and 6. Three of the 10 aqueous treated fibers observed had the stripped appearance of the fiber pictured in Figure 8. For the methanol and methylene chloride treatments, all hair strands observed exhibited some degree of scale lifting as depicted in Figures 3 and 4.