Microplastic serves as a potential vector for Cr in an in-vitro human digestive model

• Published in: The Science of the total environment Vol. 703; p. 134805
• Main Authors: Liao, Yu-liang, Yang, Jin-yan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.02.2020
• Subjects: Adsorption; Adult; adults; bioavailability; Child; children; Chromium; Chromium adsorption; Degradable microplastic; desorption; females; heavy metals; Human health risk; Humans; in vitro studies; In-vitro digestion model; large intestine; males; Metals, Heavy; Microplastic ingestion; Microplastics; mouth; Plastics; poly(vinyl chloride); polyethylene; polypropylenes; polystyrenes; small intestine; Water Pollutants, Chemical; In-vitro digestion model; Degradable microplastic; Chromium adsorption; Human health risk; Microplastic ingestion
• DOI: 10.1016/j.scitotenv.2019.134805
• ISSN: 0048-9697; 1879-1026

[Display omitted] •Microplastics (MPs) released more Cr in the in-vitro digestive model than in fresh water.•Gastric phase aroused the most bioaccessible Cr(VI) and Cr(III).•Cr on degradable MP was more bioaccessible than Cr on nondegradable MPs.•The Cr exposure via MP consumption was estimated for different human groups.•Cr on degradable MP may pose higher noncarcinogenic risks to human. Microplastics (MPs), polymer particles capable of adsorbing heavy metals from ambient environment, have been found in diverse human food resources. Through the consumption of MPs, heavy metals adsorbed on MPs might be transported into human body. This study aims to explore the behavior of heavy metal-contaminated MPs in human digestive system which is not previously researched. Firstly, a chromium (Cr) adsorption/desorption study was conducted with four commonly used nondegradable MPs [polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and polystyrene (PS)] as well as one degradable MP (polylactic, PLA). Then, the whole digestive system in-vitro method (WDSM), a systematic model including mouth, gastric, small intestine, and large intestine digestive phases, was conducted on the Cr-loaded MPs. Additionally, the bioaccessibilities and hazard quotients (HQs) of Cr(VI) and Cr(III) were evaluated. Among five MPs, although PLA showed the weakest adsorption capacity for Cr, the Cr(VI) bioaccessibilities for PLA reached the highest values of 19.9%, 15.6% and 3.9% in gastric, small intestinal and large intestinal phases, respectively. The bioaccessibilities of Cr(VI) in gastric phase were significantly higher than those in other phases, while no Cr release from MPs was detected in the mouth phase. In gastric phase, the bioaccessibilities of Cr(VI) were significantly higher than those of Cr(III) in the gastric phase, and both of them approached to a similar level in intestinal phases. In the WDSM, the HQs of Cr(VI) and Cr(III) on MPs were lower than the critical level for both adults and children. Based on the measured bioaccessibilities, the maximum daily total Cr intake for different human groups (female children, male children, female adults and male adults) through MP consumption was estimated from 0.50 to 1.18 μg/day. In general, the five tested MPs were potential to serve as Cr vectors in the WDSM.