Exposure and toxicokinetics of microplastics in arthropods: Mechanisms and consequences

Arthropoda, the largest and the most diverse invertebrate Phylum, are increasingly impacted by microplastic (MP) pollution across varied range of habitats. This review synthesizes toxicity of MPs in different taxa of arthropods with references to exposure route, tissue level accumulation and toxicokinetic behaviour with a focus on physiological outcomes. This review article comprehensively identified that gut and gill are the primary sites of MP accumulation. Toxicokinetics, including absorption, distribution, metabolism and excretion (ADME) were explored to assess the behaviour of MP from ingestion to egestion within arthropod system. Among the polymers, polystyrene is the most studied and frequently associated with invoking toxicity in different species of arthropod. Oxidative stress, immune modulation, altered growth, survivability and reproductive fitness appears to be the key toxicological responses. Impairment of feeding behaviour, locomotion and prey-predatory interactions have also been documented. Additives and environmental contaminant adsorb on MPs were reported to intensify the toxicity in many arthropod species. These findings highlight the vulnerability of arthropods to MP pollution and underscore the risk at broader ecological level due to having their role in food web, nutrient cycling and environmental monitoring. This review also identifies the research gaps highlighting the limited data availability in terrestrial arthropods, long-term exposure and multi-generational studies, emphasizing the need for integrative approaches to assess MP toxicity under environmental realistic conditions.