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Disposition of [14C]-polystyrene microplastics after oral administration to lactating sheep
Weilin L Shelver1, Amy M McGarvey1, Lloyd O Billey1
1USDA Agricultural Research Service, Edward T. Schafer Agricultural Research Center, Fargo, North Dakota, USA.
Abstract:
Microplastics have become a ubiquitous contaminant, but their fate in food animals is largely unknown. In this study, [14C]-polystyrene microplastic (PS-MP) particles were orally dosed to lactating sheep to evaluate their absorption and disposition. Elimination of the [14C]-PS-MP was predominately through faeces with faecal radioactivity peaking at 24 h post-dosing but continuing to be present throughout the entire 72 h study period. Only a small fraction (≤ 1%) of the dosed [14C]-PS-MP was present in blood, milk, and urine. Pharmacokinetic analysis of blood plasma radioactivity, using non-compartment modeling, indicated rapid absorption (T1/2 0.4 to 3 h) with slow elimination (T1/2 37 to 48 h). Radioactivity in milk and urine had similar elimination patterns with radiocarbon activities peaking 24 h post-dosing with detectable elimination throughout the 72 h study period. No radioactivity was quantifiable in tissues at the 72 h withdrawal period.
Insights
Polystyrene microplastics are poorly absorbed by sheep, with most excretion occurring via feces. Detectable levels in milk and urine were minimal, with no tissue accumulation observed within 72 hours.
Area of Science:
- Environmental Science
- Toxicology
- Animal Science
Background:
- Microplastics are widespread environmental contaminants.
- Their impact on food animals remains poorly understood.
- Assessing microplastic fate in livestock is crucial for food safety.
Purpose of the Study:
- To investigate the absorption and disposition of orally administered polystyrene microplastics (PS-MP) in lactating sheep.
- To quantify the elimination pathways and tissue distribution of PS-MP.
Main Methods:
- Lactating sheep were orally dosed with radiolabeled [14C]-polystyrene microplastic particles.
- Radioactivity was measured in feces, blood, milk, urine, and tissues over a 72-hour period.
- Pharmacokinetic analysis using non-compartment modeling was performed on blood plasma data.
Main Results:
- Predominant elimination of [14C]-PS-MP was via feces, peaking at 24 hours post-dosing.
- Less than 1% of the dosed radioactivity was found in blood, milk, and urine.
- Rapid absorption (T1/2: 0.4–3 h) and slow elimination (T1/2: 37–48 h) were observed in blood plasma.
- Radioactivity in milk and urine showed similar elimination patterns, peaking at 24 hours.
- No quantifiable radioactivity was detected in tissues after 72 hours.
Conclusions:
- Oral administration of polystyrene microplastics to sheep results in limited absorption and minimal systemic distribution.
- The primary route of elimination is fecal, suggesting low potential for accumulation in edible tissues.
- Further research is needed to understand the long-term effects and potential risks associated with microplastic ingestion in food animals.
