Silent threats beneath the surface: unraveling the impact of organophosphate toxicity on fish

Abstract

Insecticides, a subset of pesticides, play a crucial role in enhancing human well-being by combating vector-borne illnesses and safeguarding crops from harmful organisms. Among these, organophosphate insecticides are extensively utilized for agricultural, household, and industrial pest management. Despite their reduced environmental persistence, organophosphates can have adverse effects on non-target species. The widespread and increasing use of these compounds has led to their frequent detection in environmental samples, living organisms, and residential areas across various generations and types. Organophosphate insecticides exhibit high toxicity to a range of animals, including mammals, birds, amphibians, and aquatic life such as fish. This critical review examines the presence, behavior, metabolic processes, and bioavailability of organophosphate insecticides in aquatic environments. Additionally, it discusses biomarkers used to assess the toxic effects of these compounds on fish. The deleterious impacts of organophosphate insecticides on fish encompass oxidative stress and damage, including the generation of reactive oxygen species and lipid peroxidation. Other effects include neurological and behavioral abnormalities, developmental issues such as delayed growth and signalling disruptions, biochemical changes in protein, glucose, and enzyme levels, and alterations in blood components like white blood cells, red blood cells, and hemoglobin. Furthermore, these insecticides can affect physiological processes related to metabolism, cause histopathological changes in organs such as the brain, liver, intestine, kidney, heart, muscles, spleen and gills, and induce molecular toxicity, including DNA damage, micronuclei formation, and altered gene or mRNA expression. Reproductive and endocrine disruption, such as interference with pathways and signalling, are also observed. In conclusion, this review emphasizes the substantial and varied toxicological impacts of organophosphate insecticides on fish across multiple biological levels, underscoring the urgent necessity for effective control measures to safeguard aquatic ecosystems.