Investigation of Toxicity of the Combined Exposure of Microplastics and Arsenic (III) on Clams

Background: Microplastics is a new type of global pollutant that can absorb pollutants in the environment and enter the food chain. Arsenic (As) is a kind of heavy metal element, and its pollution to the environment has been triggered concern. Currently, the escalating threat to marine ecology posed by both microplastics and heavy metal pollution is garnering increasing attention, particularly concerning their detrimental impact on human health Methods: The aim of this paper is to study the adsorption of As by microplastics and their combined toxic effects on clams, which were determined by joint toxicity test. Results: During the initial 48 hours, the fatality rates for larval clams exposed to As (III)- adsorbed microplastics, including polypropylene (PP), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), and polymethyl methacrylate (PMMA) at concentrations ranging from 10 mg/L to 500 mg/L, varied in the range of 0-30.0%, 0-10.0%, 0-30.0%, 0-15.0%, and 0- 50.0%, respectively. Similarly, adult clams exhibited fatality rates within the ranges of 0-35.0%, 0-25.0%, 0-30.0%, 0-50.0%, and 0-15.0%. However, these rates increased significantly after 48 hours, reaching 80.0% (PP), 62.0% (PE), 40.0% (PS), 60.0% (PVC), and 70.0% (PMMA) for larval clams, and 85.0% (PP), 72.0% (PE), 40.0% (PS), 72.0% (PVC), and 65.0% (PMMA) for adult clams, respectively. In contrast, when exposed to microplastics concentrations exceeding 1000 mg/L with adsorbed As (III), both larval and adult clams experienced fatality rates that initially peaked between 55.0% and 100.0% within the first 48 hours. Throughout the entire incubation period with As (III) alone, the fatality rates for larval and adult clams remained relatively low, ranging from 0-20.0% and 0-15.0%, respectively. Conclusion: The mortality rate of clams directly correlated with the input of microplastic particles containing As (III); specifically, an increase in the concentration of microplastics resulted in higher fatality rates and accelerated death rates among the clams. Clams demonstrated varying toxicological responses to the different types of microplastics.