Abstract

End-of-life is important when determining a materialʼs sustainability credentials. Raw hides/skins are naturally biodegradable and, therefore, leather can play a key role in a sustainable circular future. The addition of chemicals during tanning alters the disintegration rate and, different tanning methods likely produce leather with various toxicities.

Leather samples tanned using different methods were analysed for detectable values of common toxins. Ecotoxicological screening was carried out on 5-samples of each type of leather (chrometanned, chrome-free and vegetable-tanned). Chrome-tanned leather had significantly more detectable levels of chromium than other leathers. Vegetable-tanned leathers had significantly more detectable levels of extractable petroleum hydrocarbons compared to other samples.

At end-of-life, toxins from biodegradable leathers may contaminate soil. Oxidants within soil oxide Cr(III) to more toxic Cr(VI). Chromium is taken up by plants, impacting growth and development, due to its structural similarity to other essential nutrients. Petroleum hydrocarbons negatively impact soil enzyme activities which alters nutrient availability. These hydrophobic compounds stunt plant growth and development and exert a carcinogenic effect. Toxins within soils may affect organisms directly through ingestion or indirectly through bioaccumulation which poses a risk to human health.

Although the tanning method influences the ecotoxicological screen, the leather-making process is diverse (depending on desired leathers properties and application) and therefore, tanning type is not an accurate determinant of leather toxicity. Furthermore, the ecotoxicological screen is not comprehensive and, therefore, compounds with high toxicity may not be currently detected. Ecotoxicological screening methods should be improved to cover all compounds of concern.