Rubber-related chemical contamination in milk: Implications for dairy production systems

Rubber-related chemicals are widely used in tires and technical rubber products, but their occurrence in food remains poorly understood. This study analyzed 17 raw milk samples and rubber components from dairy production systems for benzothiazoles, guanidine accelerators, and p-phenylenediamine antioxidants. Four compounds (S-BTH, DPG, 6-PPD, and 6-PPD-Q) were detected in milk (38.8-26,258.5 ng/L), with at least one quantified in 41% of samples (7/17), whereas none of the target compounds were detected in the three samples collected from alpine farms. Fourteen rubber-related chemicals were identified in milk-contact rubber components (42.9 μg/g-3.7 mg/g). Solubilization experiments confirmed partial leaching, with released chemical profiles reflecting bulk material composition. These findings indicate that rubber-related chemicals can occur in raw milk and that both environmental sources and migration from food-contact materials represent potential contamination pathways. However, the limited sample size and absence of a clear relationship with road traffic intensity preclude identification of the predominant contamination source.