Effect of pH and ionic strength on exposure and toxicity of encapsulated lambda–cyhalothrin to Daphnia magna

Abstract

Encapsulation of pesticide active ingredients in polymers has been widely employed to control the release of poorly water-soluble active ingredients. Given the high dispersibility of these encapsulated pesticides in water, they are expected to behave differently compared to their active ingredients; however, our current understanding of the fate and effects of encapsulated pesticides is still limited. In this study, we employed a central composite design (CCD) to investigate how pH and ionic strength (IS) affect the hydrodynamic diameter (HDD) and zeta potential of encapsulated λ-cyhalothrin and how those changes affect the exposure and toxicity to Daphnia magna. R(2) values greater than 0.82 and 0.84 for HDD and zeta potential, respectively, irrespective of incubation time suggest those changes could be predicted as a function of pH and IS. For HDD, the linear factor of pH and quadratic factor of pH×pH were found to be the most significant factors affecting the change of HDD at the beginning of incubation, whereas the effects of IS and IS×IS became significant as incubation time increased. For zeta potential, the linear factor of IS and quadratic factor of IS×IS were found to be the most dominant factors affecting the change of zeta potential of encapsulated λ-cyhalothrin, irrespective of incubation time. The toxicity tests with D. magna under exposure conditions in which HDD or zeta potential of encapsulated λ-cyhalothrin was maximized or minimized in the overlying water also clearly showed the worst-case exposure condition to D. magna was when the encapsulated λ-cyhalothrin is either stable or small in the overlying water. Our results show that water quality could modify the fate and toxicity of encapsulated λ-cyhalothrin in aquatic environments, suggesting understanding their aquatic interactions are critical in environmental risk assessment. Herein, we discuss the implications of our findings for risk assessment.

Field application of nanoliposomes delivered quercetin by inhibiting specific hsp70 gene expression against plant virus disease

“…The particle size, zeta potential and PDI also confirmed this phenomenon, and the particle size was significantly reduced after adding HACC and Tween 80. Many properties, including water solubility, permeability, adhesion and so on, could be improved by preparing traditional chemical pesticides as nanoscale particles [ 49 ]. At the same time, the zeta potential of the nanoliposomes exceeded 50 mV, which meant that the particles had good dispersibility.…”

Effects of three tebuconazole nanopesticides on the survival of Daphnia magna

“…Insight into possible changes in NC properties compared to their stock suspension is essential as it is predicted that NCs' physical properties in facing real environments will change. 32,35 To understand the fate and behavior of NCs with the exposure conditions, it is crucial to assess the physicochemical properties of NCs in the exposure media. 74 Plots A, B, and C in Fig.…”

“…These should consider not only chemical composition but also particle-specific properties like size, surface charge, particle distribution, number of particles, surface properties, and aggregation. [33][34][35] Nanomaterials introduce new methodological challenges in ecotoxicology, underscoring the need for standardized testing and robust regulations that account for their dynamic behavior. 36,37 Current legislation for plant protection products, however, does not adequately address these nanosize-specific features, particularly in environmental fate and risk assessment.…”

Field Application of Nanoliposomes Delivered Quercetin by Inhibiting Specific hsp70 Gene Expression Against Plant Virus Disease

“…The earlier de nition of nanoagricultural products refers to agricultural products whose half particle size is less than 100 nm, and the particle size of the nanoliposomes prepared in this study was controlled at 100 nm, which met the standards for nanoagricultural products. Many properties, including water solubility, permeability, adhesion and so on, could be improved by preparing traditional chemical pesticides as nanoscale particles [50]. At the same time, the zeta potential of the nanoliposomes exceeded 50 mV, which meant that the particles had good dispersibility.…”