Assessment of toxic polycyclic aromatic hydrocarbons (PAH) in recycled plastics: A comparative study of LDPE, HDPE, PET, and PP

Polycyclic aromatic hydrocarbons (PAHs) are toxic, potentially carcinogenic compounds that can be present in recycled plastics, raising concerns about human health and environmental safety. Despite their widespread use, recycled polymers are not routinely monitored for these contaminants. This study analysed 25 recycled plastic samples from recycling companies—including LDPE, HDPE, PET, PP, and polymer mixtures—to assess the presence of PAHs and evaluate an extraction method optimised for LDPE. The method's applicability to other polymer types was also explored, along with potential correlations between PAH levels and factors such as polymer type, origin, and colour. PAHs were extracted by stirring the samples for 24 h at room temperature in a 1:1 acetone/dichloromethane mixture, followed by purification using C18 solid-phase extraction cartridges. Results showed that PET samples had the lowest total PAH concentrations, often below detection limits. In contrast, one black LDPE sample exhibited the highest total PAH content at 2200 ng/g and toxicity value (68 ng TEQ/g). The study reveals significant variability in PAH content depending on polymer characteristics and recycling processes. These findings highlight the limitations of current industrial washing methods in removing persistent organic contaminants and underscore the need for improved control strategies and regular monitoring to ensure the safety of recycled plastics.