Microplastics are not important for the cycling and bioaccumulation of organic pollutants in the oceans—but should microplastics be considered POPs themselves?

Abstract

Abstract   The role of microplastic particles in the cycling and bioaccumulation of persistent organic pollutants (POPs) is discussed. Five common concepts, sometimes misconceptions, about the role of microplastics are reviewed. While there is ample evidence that microplastics accumulate high concentrations of POPs, this does not result in microplastics being important for the global dispersion of POPs. Similarly, there is scant evidence that microplastics are an important transfer vector of POPs into animals, but possibly for plastic additives (flame retardants). Last, listing microplastics as POPs could help reduce their environmental impact. Integr Environ Assess Manag 2017;13:460–465. © 2017 SETAC Key Points Microplastics accumulate POPs relative to their surroundings, acting as passive samplers, yet there are insufficient microplastic particles to affect the global cycling of POPs. Laboratory experiments exposing clean animals to POP-contaminated microplastics observe the transfer of POPs into the animals but cannot demonstrate that this pathway is relevant in the field. Field observations of POPs in animals show little evidence that the ingestion of microplastics contributed much to their body burden with the exception of plastic additives. Microplastics should be considered as POPs as they share persistence, long-range transport, potential for bioaccumulation, and adverse effects with other POPs.