Plastic materials have become an intrinsic part of modern society due to their durability, ease of processing, and low cost. The properties can be easily tuned by incorporating additives which impart features such as colour, flexibility, or UV stability. However, many additives are also hazardous substances, for example phthalates and phenolic benzotriazoles. Across all aspects of the value chain - from manufacturing to use, recycling, and waste management - plastics can be lost to the environment. Much of this plastic pollution ends up in streams, rivers, and lakes and is eventually transported into the world’s oceans. In the environment, plastic pollution may cause harm through the release of additives and subsequent uptake by organisms, either as a disperse contaminant or through ingestion of plastic. To understand the risk to marine wildlife, the type and concentration of additives in plastic debris must be established.
In this study we report the quantification of 31 common plastic additives (including plasticisers, antioxidants, and UV stabilisers) in beached plastic debris from across Aotearoa / New Zealand. Plastic debris was collected by citizen scientists across 20 locations spanning a diverse range of coastal environments. Additives were isolated by solvent extraction and quantified using LC-MS. Additives were detected in all samples (n = 200), with a median of four additives per piece. The additives bis(2-ethylhexyl) phthalate, diisononyl phthalate, diisodecyl phthalate, and antioxidant 702 were detected at the highest concentrations up to 197,000 µg/g. Additive concentrations were significantly higher in polyvinyl chloride plastics, primarily due to the presence of phthalate plasticisers. Dibutyl phthalate was detected with the highest frequency (96 %) across all samples, indicating adsorption of ambient dibutyl phthalate. This study highlights phthalates and polyvinyl chloride as key targets for consideration in ecotoxicology studies, risk assessments, and policy change.