Levels of perfluoroalkyl carboxylic acids in recycled plastic pellets: A small input into the plastics cycle.

Perfluoroalkyl carboxylic acids (PFCAs) are used in electrical products and food packaging, and could enter the circular plastic economy. In this study, the concentrations of PFCAs (C6 to C15) were measured in 99 recycled plastic pellet samples collected in Japan and nine selected countries from 2021 to 2024. The concentration distribution of PFCAs in recycled plastic pellets (n = 99) was 59% below 50 ng/kg for total PFCAs. The average total PFCA concentration in the samples from Japan (n = 68) was 73 ng/kg (16 ng/kg from perfluorooctanoic acid, PFOA) and the maximum concentration was 540 ng/kg (88 ng/kg from PFOA). For comparison, the primary plastic pellets from Japan were also analyzed and the concentrations in eight out of nine samples were below the detection limit and very low concentrations (2.7 ng/kg) were detected in the other sample. The concentrations of PFCAs in the recycled plastic pellets were significantly higher than those in the primary plastic pellets (p < 0.05, Student's t-test), indicating that some PFCAs used in plastic products enter the circular plastic economy. Total PFCA concentrations in recycled pellets from overseas averaged 110 ng/kg (PFOA: 24 ng/kg) and the maximum concentration was 590 ng/kg (PFOA: 130 ng/kg). These concentrations were comparable to those found in pellets from Japan. Branched isomers of PFCAs were detected in the recycled pellets, albeit at concentrations an order of magnitude lower than those of the linear PFCAs. According to the results of this study, even when the sum of linear and branched PFCAs is considered, the amount of PFCAs present in recycled plastics is at parts per trillion levels, suggesting that the concentrations of PFCAs in average recycled plastic pellets are not high enough to hinder the promotion of recycling.