en Environmental Health, Sciences, and Engineering Environmental Health, Sciences, and Engineering Review Review Article <div class="WordSection1" style="text-align: justify;"><span style="line-height:1;"><span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="page:WordSection1"><b>Background: </b>The ubiquitous presence of microplastics (MPs) in global drinking water supplies has emerged as one of the most pressing environmental health challenges of the 21st century.<br> <b>Methods: </b>A systematic search of PubMed, Scopus, Web of Science, and Google Scholar was conducted for studies published between January 2015 and December 2024. Forty-seven peer-reviewed studies reporting MP concentrations in tap water, bottled water, groundwater, and surface water used for human consumption were included. Risk assessment was conducted in accordance with U.S. EPA and WHO guidelines.<br> <b>Results: </b>Pooled MP concentrations ranged from 0.7 to 7,000 particles/L across water types, with bottled water exhibiting significantly higher levels (mean = 325 particles/L) than tap water (mean = 4.2 particles/L). Polyethylene (PE), polypropylene (PP), and polystyrene (PS) were the most prevalent types of polymers. Fibers dominated in tap water (69%), while fragments predominated in bottled water (58%). Hazard quotient values exceeded 1.0 in 34% of studies, indicating non-carcinogenic risk. Cumulative cancer risk estimates for populations consuming predominantly bottled water surpassed the acceptable threshold of <m:omath><i><m:r>1&times;</m:r></i><m:ssup><m:ssuppr></m:ssuppr></m:ssup></m:omath><m:omath><m:ssup><m:ssuppr></m:ssuppr></m:ssup></m:omath><m:omath><m:ssup><m:ssuppr></m:ssuppr></m:ssup></m:omath><m:omath><m:ssup><m:ssuppr></m:ssuppr></m:ssup></m:omath><m:omath><m:ssup><m:ssuppr><span style="font-style:italic"><m:ctrlpr></m:ctrlpr></span></m:ssuppr><m:e></m:e></m:ssup></m:omath><m:omath><m:ssup><m:e></m:e></m:ssup></m:omath><m:omath><m:ssup><m:e></m:e></m:ssup></m:omath><m:omath><m:ssup><m:e></m:e></m:ssup></m:omath><m:omath><m:ssup><m:e><i><m:r>10</m:r></i></m:e><m:sup></m:sup></m:ssup></m:omath><m:omath><m:ssup><m:sup></m:sup></m:ssup></m:omath><m:omath><m:ssup><m:sup></m:sup></m:ssup></m:omath><m:omath><m:ssup><m:sup></m:sup></m:ssup></m:omath><m:omath><m:ssup><m:sup><i><m:r>-</m:r><m:r>4</m:r></i></m:sup></m:ssup></m:omath></span></span><span style="font-family:Times New Roman;"><span style="page:WordSection1"><span style="position:relative"><span style="top:2.5pt"> </span></span>&nbsp;in high-exposure scenarios.<br> <b>Conclusion: </b>Microplastic contamination in drinking water constitutes a measurable and growing public health risk. Immediate regulatory action, standardized monitoring protocols, and investment in advanced water treatment technologies are urgently required.</span></span><span style="page:WordSection1"><span style="font-family:Gulliver"><m:omath></m:omath></span></span></span><span style="font-family:Times New Roman;"><span style="page:WordSection1"><span style="font-size:9pt"><m:omath></m:omath><m:omath></m:omath></span></span></span></span><span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="page:WordSection1"><span style="line-height:normal"><m:omath></m:omath></span></span></span></span></div> <div aria-label="Page Break" class="cke_pagebreak" contenteditable="false" data-cke-display-name="pagebreak" data-cke-pagebreak="1" style="page-break-after:always" title="Page Break"></div> Microplastics, Drinking water contamination, Human health risk, Environmental toxicology, Water quality, 0 0 http://jhehp.zums.ac.ir/browse.php?a_code=A-10-711-2&slc_lang=en&sid=1 Ali Raza Agha ar.agha@stu.qom.ac.ir 100319475328460016886 0009-0006-2910-9853 Yes Faculty of Basic Sciences, University of Qom, Qom, Iran.