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

Area of Science:

• Environmental Science
• Toxicology
• Materials Science

Background:

• Microplastics (MPs) are prevalent in food sources and can adsorb heavy metals.
• The transport of heavy metals via MPs into the human body through consumption is a growing concern.
• The behavior of heavy metal-contaminated MPs within the human digestive system remains under-researched.

Purpose of the Study:

• To investigate the behavior of chromium (Cr)-contaminated microplastics (MPs) in the human digestive system.
• To assess the adsorption/desorption of Cr on various MPs and its bioaccessibility.
• To evaluate the potential health risks associated with Cr exposure from MPs.

Main Methods:

• Adsorption/desorption studies were performed on five types of MPs: polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and polylactic acid (PLA).
• A whole digestive system in-vitro method (WDSM) simulating mouth, gastric, small intestine, and large intestine phases was used.
• Bioaccessibilities and hazard quotients (HQs) of Cr(VI) and Cr(III) were evaluated.

Main Results:

• Polylactic acid (PLA) exhibited the weakest Cr adsorption but the highest Cr(VI) bioaccessibility (up to 19.9% in the gastric phase).
• Cr(VI) bioaccessibility was highest in the gastric phase and significantly higher than Cr(III) in this phase.
• Hazard quotients for Cr(VI) and Cr(III) on MPs were below critical levels for adults and children, with estimated daily Cr intake ranging from 0.50 to 1.18 μg/day.

Conclusions:

• Microplastics, particularly PLA, can act as vectors for chromium within the human digestive system.
• While current Cr intake via MPs appears low, the gastric phase is critical for Cr(VI) bioaccessibility.
• Further research is needed to fully understand the long-term health implications of heavy metal-contaminated MPs.