Chromium and leather: a review on the chemistry of relevance for allergic contact dermatitis to chromium

Abstract

As other causes decline in importance, chromium-tanned leather has become a more important source for chromium allergy, which affects around 1% of the general population. The aim of this review is to give suggestions on how to minimize the risk of leather-related allergic contact dermatitis, which can be elicited in chromiumallergic persons by hexavalent and trivalent chromium released from leather. Hexavalent chromium is the more potent chromium form and requires a lower skin dose to elicit allergic reactions. It is formed on the surface of some, antioxidant-free, leathers at dry conditions (< 35% relative humidity) and is influenced by the tanning process and other conditions, such as UV irradiation, contact with alkaline solutions, and leather age. Trivalent chromium is the dominant form released from chromium-tanned leather and its released amount is sufficient to elicit allergic reactions in some chromium-allergic individuals when they are exposed repetitively and over longer time (daysmonths). A low initial test result (< 3 mg/kg) for hexavalent chromium with the current standard test (ISO 17075) does not guarantee a low release of chromium from the leather or a low release of hexavalent chromium under typical exposure conditions during the service life of the leather. Information, labels, and certificates regarding leather products are often insufficient to protect chromium-allergic individuals. Correct labelling and information on the possible content of different allergens, as well as different tanning alternatives for certain leather products, are crucial.

Extraction of a novel tanning agent from indigenous plant bark and its application in leather processing

“…In addition, chromiumcontaining solid waste is posing a great challenge for its proper management and safe utilization. Nevertheless, several researchers have addressed the negative impact of hexavalent chromium, which could transfer to the human body via the food chain, skin, and other organs causing diseases e.g., respiratory problems, skin diseases, bone damage, renal issues, liver damage, kidney failure, infertility, cancer, and even birth abnormalities [6][7][8][9][10][11]. This situation demands a sustainable alternative to chrome tanning agents.…”

Cr (III) genotoxicity and oxidative stress: An occupational health risk for leather tannery workers of South Asian developing countries

“…Chromium (III) sulphate (Cr2(SO4)3.12H2O) is extensively used in the leather industry in the form of a basic tanning agent (Covington, 1997; Hedberg, 2020; Zhitkovich, 2011). The minimum amount of Cr (III) required to perform good tanning is approximately 4–8 g of Cr2O3 for 100 g of leather (Faridah et al, 2014).…”

No immediate effect of regulatory reduction of chromium in leather among adult patients with chromium allergy

“…In addition, it is important to note that the regulation on leather targets Cr(VI), thus not covering the presence of trivalent Cr, despite several studies suggesting its capability of eliciting ACD in patients with Cr allergy 17‐19 . Furthermore, trivalent Cr present in the leather after tanning might undergo oxidation to Cr(VI) depending on various factors including pH, vegetable retanning, ammonia treatment, thermal and photoageing, use of fatliquors, and reducing agents 20 . Despite a seemingly decreasing trend in the occurrence of Cr(VI) on the Danish market, more market studies with a wide‐range inclusion of leather products accompanied by epidemiological studies are warranted to address the efficiency of the EU regulation, regarding both leather marketing and patient outcomes.…”