Investigation of the Effects of Interactions Between Deltamethrin and Acrylic Paint Particles on Embryonic Development in Xenopus laevis

Abstract

The co-occurrence of pesticides and paint-related contaminants in aquatic ecosystems may result in interactions that modify their individual toxic effects; however, the developmental consequences of their combined exposure remain insufficiently understood. This study investigated the individual and combined effects of the widely used pyrethroid insecticide deltamethrin (DM) and two acrylic paints, which have a high potential for microplastic formation, on Xenopus laevis embryonic development, with particular emphasis on their interaction during co-exposure. Embryos at Nieuwkoop and Faber stages 8–11 were exposed for 96 h to two nominal DM concentrations (13.6 and 6.8 µg/L), to acrylic paint (100 mg/L), and to their respective combinations. Mortality, malformation rate, phenotypes, body length, and heart rate were evaluated. DM produced marked developmental toxicity, including complete mortality at the higher concentration, and substantial malformations, reduced body length, and altered heart rate at the lower concentration. Exposure to acrylic paints alone produced limitedeffects on the assessed endpoints. Under co-exposure conditions, the effects of acrylic paints varied according to the DM concentration and the developmental endpoint. At the higher DM concentration, both paints markedly increased embryo survival, whereas this effect was less pronounced at the lower concentration. Across the remaining endpoints, co-exposure modified DM-associated effects in both directions, depending on the paint and the endpoint evaluated. These findings suggest that co-exposure to acrylic paint may modify DM-related developmental toxicity, highlighting the importance of considering contaminant interactions in aquatic environmental and public health risk assessments.