Properties and Related Effects of Microplastics in the Aquatic Environment: From the Organismic to Cellular Level

Plastics have become an essential part of our everyday life. Over the past decades, increasing plastic production has resulted in a substantial rise in plastic waste, which entered the environment through littering and inadequate waste management. Although the effects of larger plastic items in the environment have been studied for quite a while, research has been focusing on microplastics (MPs) – plastic particles smaller than 1 mm, originating from the fragmentation of larger plastic items, abrasion, or direct release from industrial applications – only since the past two decades. MP particles are a very diverse suite of particles with varying physicochemical properties, which differ in size, shape, polymer type, density, unintentionally or intentionally added chemical compounds or residual monomer content, aging state, surface charge, surface roughness, environmental coating, and biofouling as well as other physicochemical parameters. Once released, this complexity increases even further due to interactions with biotic and abiotic environmental factors. Abiotic interactions are primarily related to exposure to physical or chemical factors that lead to aging such as UV-radiation. Interactions with biotic factors range from the formation of an, depending on the particle size, eco-corona or biofilm on the surfaces of an MP particle to uptake by various organisms, which potentially also modifies their physicochemical properties. On the other hand, MPs have been shown to affect organisms at different biological levels, from the base of the food web up to top predators. The reported effects of MPs range from highly toxic to negligible, making it challenging to draw general conclusions about the hazards of MPs. To enlighten the variable results in the ecotoxicity of MPs, this chapter explores the wide range of MP physicochemical properties and their potential influence on interactions with and effects on organisms and cells.