Assessing the presence of microplastic in agriculture soils irrigated with treated waste waters using Lumbricus sp.: Ecotoxicological effects

Global water scarcity entailed the use of treated wastewater (TWW) in agriculture, however, this water can vehiculate numerous pollutants into soil and further crops such as microplastics (MPs). To date, few studies had quantified the accumulation of MPs in soils and earthworms after irrigation with TWW as well as their toxicological effects. Hence, the main objective of the present work is to evaluate the toxicity of MPs using Lumbricus sp. earthworms collected from TWW irrigated soils with an increasing gradient of time (5 years, 16 years and 24 years). MPs determination in soil, as well as in earthworms were performed. The intestinal mucus was quantified, and cytotoxicity (Lysosomal membrane stability (LMS), Catalase (CAT) and glutathione-S-Transferase (GST) activities), neurotoxicity (Acetylcholinesterase activity (AChE)) and genotoxicity (Micronuclei frequency (MNi)) biomarker were assessed. Our results revealed that the use of TWW rendered MPs accumulation in earthworms' tissues and induce alteration on the intestinal mucus. An important cytotoxicity time-depending was observed being associated with an increase on genotoxicity. Overall, the present investigation highlights the ecotoxicological risk associated with the use of TWWs as an important driver of MPs and consequently measures are necessary to reduce MPs in wastewater treatment plans to improve this non-conventional water quality.