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Microplastics (MPs) and nanoplastics (NPs) have increasingly been found in the environment. Until recently, most MPs/NPs toxicological research has been done in aquatic systems resulting in a gap in knowledge regarding terrestrial systems. Plastics have been shown to enter the circulatory system of humans, and can accumulate within organs, little is known about the effect this has on health. Heart disease is the leading cause of death globally, so it's critical to understand the possible impacts MPs/NPs have on the heart. The Drosophila model has been growing in popularity within the toxicology field, it allows for affordable and rapid research on the impacts of a variety of toxins, including plastics. Some research has examined toxicological effects of plastics on the fly, evaluating the effects on mortality, fecundity, development, and locomotion. However, no one has studied the effects on the Drosophila heart. We utilize the Drosophila model to identify the potential effects of oral exposure to polystyrene MPs (1 µm in diameter) and NPs (0.05 µm in diameter) particles on heart function. Flies were exposed to 1.4 x 1011 particles/d/kg of larvae for MPs and 1.2 x 1018 particles/d/kg of larvae for NPs from egg to pupal eclosion. Heart function was then analyzed utilizing semiintact dissections and Semi-automatic Optic Heartbeat Analysis software (SOHA). Following exposure to MPs and NPs we see sexually dimorphic changes to heart size and function. This study highlights the importance of additional Drosophila MPs/NPs research to identify the molecular mechanisms behind these changes. [ABSTRACT FROM AUTHOR]

As the levels of plastic use in global society have increased, it has become crucial to regulate plastics of all sizes including both microplastics (MPs) and nanoplastics (NPs). Here, the published literature on the current laws passed by the US Congress and regulations developed by various federal agencies such as the US Environmental Protection Agency and the US Food and Drug Administration (FDA) that could be used to regulate MPs and NPs have been reviewed and analyzed. Statutes such as the Clean Water Act, the Safe Drinking Water Act, the Toxic Substances Control Act (TSCA), the Resource Conservation and Recovery Act, and the Clean Air Act can all be used to address plastic pollution. These statutes have not been invoked for MP and NP waste in water or air. The Federal Food, Drug, and Cosmetic Act provides guidance on how the FDA should evaluate plastics use in food, food packaging, cosmetics, drug packaging, and medical devices. The FDA has recommended that acceptable levels of ingestible contaminant from recycled plastic are less than 1.5 µg/person/day, which is 476 000 times less than the possible ingested daily dose. Plastic regulation is present at the state level. States have banned plastic bags, and several cities have banned plastic straws. California is the only state beginning to focus on monitoring MPs in drinking water. The future of MP regulation in the USA should use TSCA to test the safety of plastics. The other statutes need to include MPs in their definitions. For the FDA, MPs should be redefined as contaminants—allowing tolerances to be set for MPs in food and beverages. Through minor changes in how MPs are classified, it is possible to begin to use the current statutes to understand and begin to minimize the possible effects of MPs on human health and the environment. Integr Environ Assess Manag 2023;19:474–488. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Key Points: Microplastics (MPs) and nanoplastics (NPs) are largely absent from regulatory statutes.The typical American ingests 467 000 times the recommended acceptable daily dose of recycled plastic.Both the science of MP and NP research and regulatory policies must be addressed to solve the plastic crisis.By redefining MPs as toxic or contaminants, these particles can use the existing statutes for regulatory purposes. [ABSTRACT FROM AUTHOR]