Specialty chemicals company LANXESS commissioned a study by the independent Institute for Material Testing. The study proved that biocides required for the preservation of leather intermediates do not migrate out of the finished leather articles.

The results of the migration study are critical for assessing the potential risks associated with biocide residues in leather articles. By measuring the amounts of biocide migrated, experts can assess the likelihood of human exposure and any associated risk.

Biocides such as PCMC (4-chloro-3-methylphenol), OPP (orthophenylphenol) (2-phenylphenol), OIT (octylisothiazolinone) and TCMTB (2-(thiocyanomethylthio)benzothiazole) are widely used in the leather tanning process. They prevent microbial attack, decay and spoilage in leather intermediates, including Wet Blue and Wet White. Their antimicrobial properties provide effective preservation of leather intermediates during production and storage.

Despite a thorough and state-of-the-art processing and treatment, finished leather products may contain biocide residues. This can raise concerns about potential risks to consumers who wear leather items such as shoes, bags and garments and thus have direct skin contact. “Our current migration study is therefore critical in providing insights into the migration of biocides from leather products. The study simulated the conditions to which leather products may be exposed during their life cycle,” says Andreas Weckmann, Technical Application Manager Leather at LANXESS.

The migration test investigated whether the four biocides migrated into a cotton fabric soaked with artificial sweat solution. All measured values were below the detection limit.

“The fact that there were no detectable biocide residues in the cotton fabrics soaked in sweat solution means an additional level of safety for the consumer. The results of the study prove that the unwanted biocide residues from the unavoidable preservation in the leather manufacturing process do not migrate out of the finished leather article,” emphasizes Weckmann.