Abstract
This presentation will provide an overview of current knowledge regarding additive chemical content of plastics, analysis and leaching; both aqueous leaching and bioleaching to organisms following plastic ingestion. Data from a range of studies related to plastic additive chemicals will be presented. There will be a particular focus on the challenges involved in the identification and quantification of a potentially large number of organic and inorganic additives with a wide range of physicochemical properties. Synthetic polymer-based materials are ubiquitous in aquatic environments, where weathering processes lead to the leaching of additive chemicals. In addition to the risks associated with conventional thermoplastics (e.g. PVC, PET, polyethylene or polystyrene), concerns are emerging about the possible impacts of other polymer-based materials, including microparticles derived from car tire rubber (CTR). Most thermoplastics contain a variety of additive chemicals that either aid the production process or impart specific properties to the final product. These chemicals include a wide range of organic and inorganic compounds, which may represent a high percentage of the final plastic materials (in some cases up to 50%). While several additives (e.g. bisphenol A, phthalates and brominated flame retardants) have been shown to adversely affect aquatic species, and are known environmental contaminants, exposure to leached plastic additive mixtures has received far less attention, and knowledge regarding release, fate and effects is limited. The impacts of additive chemical exposure will be discussed in relation to different polymer types and their associated additive chemical profiles. Furthermore, the focus and interpretation of existing microplastic effects data on physical particle properties will be reconsidered with respect to additive chemical content. The presentation concludes with a recommendation for new approaches for microplastic effects assessments and a call for more data concerning the environmental concentrations of plastic additive chemicals, especially those not currently being routinely monitored.