A review on microplastics in mammalian feces: Monitoring techniques and associated challenges

The global ecosystem is facing a rapidly escalating contamination issue with microplastics (MPs), which has raised concerns about human exposure and potential health effects. This review focuses on MP contamination in mammalian feces and evaluates current monitoring techniques and associated challenges. In humans, the most prevalent MP polymers identified in human feces include polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyamide (PA), polyvinyl chloride (PVC), polycarbonate (PC), and polyurethane (PU). Additionally, PET and PC were found in the feces of dogs and cats, too. In harbor seal feces, the identified polymer types included cellophane, rubber, alkyd resin, and ethylene-propylene-diene-monomer (EPDM). This review determined that the size of the MPs in human feces ranged from 1 µm to 5000 µm. The detection of MPs in the feces of humans and other mammals suggests that fecal MP monitoring can be used as a non-invasive biomonitoring approach to assess exposure levels and enhance environmental health surveillance. Understanding the extent of MP ingestion among organisms is crucial, considering the bioaccumulative nature of plastic pollution that currently threatens global ecosystems. Consistent monitoring of MPs in the feces of several organisms can help identify health risks and inform environmental policies aimed at reducing plastic waste and its associated impacts.