Investigating polychlorinated alkanes in technical chlorinated paraffin mixtures and polymer products available in...

Chlorinated paraffins (CPs) are chemical additives mostly composed of polychlorinated alkanes (PCAs) which may impact on the environment and human health; however, little is known about their presence in Southeast Asia. To fill this knowledge gap, we assessed 74 PCA homolog groups commonly referred to as short-chain (SCCPs: PCAs-C_10-13), medium-chain (MCCPs: PCAs-C_14-17), and long-chain CPs (LCCPs: PCAs-C_18-20) in technical CP mixtures (n = 4) and polymer samples (n = 49), including recycled plastics, collected in Vietnam in 2023. The contents of measured PCA homolog groups in technical CP mixtures were 86,000-930,000 mg/kg for PCAs-C_10-13; 85,000-990,000 mg/kg for PCAs-C_14-17; and 23,000-180,000 mg/kg for PCAs-C_18-20. Total PCAs-C_10-20 levels in polymer samples varied from 0.26 to 28,000 mg/kg and decreased in the order: soft plastic bag, electrical cable sheath, football pitch rubber, polyurethane hose, heat shrinkable tubing, spiral cable cover, plastic powder, and plastic drawstring. In polymer samples, PCAs-C_14-17 were found at greater levels (mean/median: 3000/65 mg/kg) than PCAs-C_18-20 (1300/9.5 mg/kg) and PCAs-C_10-13 (740/16 mg/kg). The contents of total measured PCAs-C_10-20 in polyvinyl chloride samples varied according to their life cycle stages, with higher levels found in recycled plastics than in feedstock and commercial product samples. The occurrence of PCAs-C_10-13 in polymer samples above internationally proposed limits for PCAs-C_10-13 in consumer goods and waste pose a conundrum for the implementation of a safe circular economy and may impact human health in Vietnam. Therefore, this study highlights key challenges for the through implementation of the Basel, Rotterdam, and Stockholm Conventions and the importance of further comprehensive investigations in Vietnam and other developing countries.