Risk assessment of metal/bio-based nanopesticides: plant growth, soil environment, and non-target organisms†

Abstract

The increasing use of nanopesticides in agriculture has raised concerns about their potential environmental health risks. Herein, we evaluate and compare the effects of metal-based nano-copper oxide (nCuO) and bio-based nano-chitosan (nCS) on tomato (Solanum lycopersicum L.) plant growth, soil environment, and non-target organisms (tadpoles). Our results showed that both nCS and nCuO significantly enhanced tomato seedling elongation, shoot and root biomass. Regarding soil health, the low concentration of nCS (10 mg kg⁻¹, nCS10) and nCuO (0.1 mg kg⁻¹, nCuO0.1) did not affect soil pH, but nCS10 increased soil total carbon (28.0%) and total nitrogen content (64.9%), and nCuO0.1 resulted in an increase in Cu content (104.5%) and a decrease in sulfur content. For high concentrations, nCuO (1 mg kg⁻¹, nCuO1) and nCS (100 mg kg⁻¹, nCS100) both led to a reduction in sulfur content without significantly impacting soil enzyme activity. Besides, nCS increased the abundance of beneficial bacteria (Aeromicrobium and Streptomyces) without impairing soil microbial functions, whereas nCuO increased the abundance of Sphingomonas, Streptomyces, and Lysobacter, as well as decreased Iamia, Altererythrobacter, and Vicinamibacteraceae, crucial for nutrient cycling, in turn undermining soil metabolic processes. In terms of non-target organism toxicity, although nCS100 exposure induced CAT decline and MDA increase resulting in lower survival rates (50.2%) of tadpoles than nCuO1 exposure (63.2%), both treatments had higher survival rates than conventional pesticides (copper guanidine acetate). Altogether, our research underscores the multifaceted risks of nanopesticides on plants, soils, and organisms, offering valuable perspectives for their potential use and the advancement of safer, environmentally friendly alternatives to nanopesticides.