Referee 2's review:

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N.B. These are the comments made by the referee when reviewing an earlier version of this paper. Prior to publication, the manuscript has been revised in light of these comments and to address other editorial requirements.
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This is an interesting article but, considering the very important conclusions, especially those concerning the field of toxicology, it needs some clarifications.

First of all, how can the Authors exclude that the high levels of As, Hg, Pb and Zn derive from modern treatment of the head, which is certainly an important museum specimen to be presserved against insect damage? In the 19th and 20th centuries, for example, extensive use of corrosive sublimate (mercury chloride) and extensive other very toxic compounds was made in the museums. The Authors should expand on this point, in order to exclude this provenance owing to the toxic elements found in the hair.

Page 6, lines 21-24: there is any hydrogen isotope useful for paleonutrition! The reported values of δ13C (-18.1‰) and δ15N (+12.4‰) show clearly an environment of C3 plants, not C4 plants or maize, and a diet rich in meat. Are the Authors sure of the South-American provenance of the specimen? The Authors need to supply more anthropological and historical information.

The term toxin indicates biological products; therefore, in this context, the term "toxic element" would be more appropriate.

Some mistakes:

Page 7, line 8: correct C14 into C4.
Table 2 (and caption): correct Zink into Zinc