Ecological and ecotoxicological analysis of the toxicity of microplastics and pesticides, isolated and in mixtures, using a multispecies test system

Abstract

Contamination of the environment by plastic particles [e.g., particles < 5 mm in size known as microplastics (MPs)] has emerged as among the most prominent issues currently confronted by government environmental agencies globally. Although these particles generally have low toxicity, they are highly persistent and their ability to sorb toxicants and leach their additives has the potential to alter the environmental fate and ecotoxicity of these substances. Plastic materials used within the agriculture sector are one major source of MPs into freshwaters, and substances such as pesticides can be associated with these particles generating unknown consequences in the environment. Pesticides are among the greatest challenges to sustainability in the agribusiness model and the environmental implications of pesticides are likely affected by the presence of MPs. An ongoing challenge to understanding the environmental fate of pesticides is processes that influence their sorption to particles in the aqueous phase, and these particles now include the presence of MPs. In this project, we propose a multidisciplinary approach to investigate how pesticides and microplastics mutually and individually influence their fate, transport and toxicity in soil and freshwater ecosystems. Both pesticides and MPs are highly relevant environmental contaminants in freshwaters of countries such as Brazil, which combine large regions of intensive agricultural production that have strong impacts on the provision of ecological services in these environments. The innovative integrated experimental design will include (1) laboratory and mesocosms experiments to better understand the sorption/desorption of pesticides to MPs under different environmental conditions, presence of biofilms, plastic additive, etc. and, (2) key toxicological tests (acute and chronic) to assess bioavailability, behavioral and physiological effects and lethal concentration caused by association of those contaminants to organisms, in addition to the effects on ecosystem functions and services.