Microplastic environmental behavior and health risk assessment: a review

Total plastic production is expected to reach 33 billion tons by 2050, and microplastic emissions from effluents to the environment range from 0.46 million to 140 billion tons. Microplastic distribution and toxicological effects are actually poorly known. Here we review microplastic pollution with emphasis on their environmental distribution, their aging, their analysis in the environment and living organisms, their toxicity alone or combined with other contaminants, and their mitigation techniques. We present microplastic distribution in soil, water, and the atmosphere. Microplastic aging is controlled by physical, chemical, and biological factors. Model organisms of microplastic exposure include zebrafish, earthworms, Caenorhabditis elegans, and Arabidopsis thaliana. Microplastic exposure to humans could induce gastrointestinal, pulmonary, reproductive, and cardiovascular toxicity, and neurotoxicity. We discuss the combined toxicity of microplastics with organic pollutants, heavy metals, endocrine disruptors, and antibiotics. Fourier transform infrared spectroscopy and Raman spectroscopy are currently the most commonly used techniques for microplastic analysis.