en Pediatrics Letter to the Editor Letter to the Editor <span style="line-height:3;">Microplastics (MPs) are an emerging environmental contaminant that has raised public concern [1, 2]. MPs are plastic particles less than 5 mm in size. MPs are polymers, usually containing carbon, oxygen, hydrogen, and/or silicon. Polyethylene, polyamide, polypropylene, and poly (ethylene terephthalate) are the most common polymers. The MPs have various forms, including fibers, fragments, and films, and colors, including colorless, black, and brown forms. They are found in tap water, bottled water, beverages, air, oceans, and soil.</span><br> &nbsp; Carcinogenesis Risk, Children Health, Immune System, Microplastics 277 280 http://jpr.mazums.ac.ir/browse.php?a_code=A-10-1222-2&slc_lang=en&sid=1 Ismaeil Alizadeh ismaeil.alizadeh@yahoo.com 100319475328460013072 100319475328460013072 No Department of Vector Biology and Control of Diseases, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Maryam Faraji m.faraji@kmu.ac.ir , m_faraji28@yahoo.com 100319475328460013073 100319475328460013073 Yes Environmental Health Engineering Research Center, Kerman University of Medical Sciences, Kerman, Iran.