The Conditions and Quality of Postmortem Hair Sampling May Have a Subsequent Impact on the Interpretation of Toxicological Results in Hair.

Abstract

In “postmortem” cases of high-energy trauma or extensively decomposed bodies, typical samples used for toxicological investigation (i.e., blood or urine) may not be available. In this context, alternative matrices (i.e., nails and hair) have proven to be valuable substitutes (1). Hair grows at around 1 cm per month (0.9–1.2 cm owing to inter- and intra-individual variations, nutrition, hormone status, etc. (2)). Consequently, segmental hair analysis provides a useful tool to determine drug exposure history. Analysis of fingernails and toenails can also be performed in “postmortem” cases alternatively and/or complementary to hair testing (3). Given the rate of nail growth speed (∼3 and 1.1 mm per month for fingernails and toenails, respectively (4)) and the incorporation of drugs along the entire length of the nails, it is routinely accepted that the windows of drug detection are 3–6 and 8–16 months in fingernail and toenail clippings, respectively (5). Nevertheless, segmental analyses cannot be performed on nails, and available data for the interpretation of nail results remain sparser than those for hair. The interpretation of results from nail or hair analyses can be complicated in cases of high-energy traumas or advanced stages of putrefaction owing to several pitfalls (e.g., external contamination by body fluids at the time of the death or by putrefaction fluids). In addition, sampling conditions can be challenging in such situations giving rise to poor-quality biological samples. The following case is intended to illustrate how a degraded quality of “postmortem” hair samples (performed by non-professionals, under poor conditions, i.e., not in an autopsy room) can have an impact on the interpretation of “postmortem” toxicological results in hair.