Effect of leather tanning process on stable isotopes and radiocarbon in tissues of Persian leopard: Preliminary results

Abstract

The international trade in animals and their parts is a multi-billion-dollar industry. Legal trade in wild animals and their derivatives is based on sustainable practices, ensuring that specimens are taken in quantities that do not threaten population stability. Unregulated or illegal international trade can jeopardise the survival of certain species by depleting wild populations. Forensic analysis is crucial in distinguishing between legal and illegal trade, particularly by determining the geographical origin or age of a specimen through methods such as stable isotope and radiocarbon analysis. The tanning process, which converts mammalian raw hides into valuable fur skins, involves the use of aggressive chemical reagents. These reagents, if absorbed by the hair or skin, can alter the original isotopic signatures, complicating forensic efforts. The extent of these alterations is not yet fully understood. The novelty of our approach lies in the fact that, for the first time, we have measured the step-by-step changes in isotopic composition throughout each individual phase of the tanning process. Previous studies have typically focused only on raw hides and final products. Additionally, we compared different tanning methods applied to a single hide. Using a leopard skin, we documented potential isotopic shifts in ¹⁴C, ²H, ¹⁸O, ¹⁵N and ¹³C during the tanning process, employing accelerated mass spectrometry and stable isotope mass spectrometry. Our preliminary findings suggest that the tanning process induces slight shifts in both stable and radioactive isotope ratios.