| Summary: | We assessed the potential for plastic ingestion in polar bears (Ursus maritimus (Phipps (1774)) using fecal analysis. Two preliminary studies were conducted to ensure our methods could effectively recover and identify plastics in polar bear feces. In the first study, in which microplastics (film, foam, or fragments) were intentionally introduced into an organic matrix, recovery rates (mean ± standard deviation) averaged 95.8 ± 14.7% (n = 18), and were significantly affected by microplastic morphology, but not digestion status. In the second study, in which microplastics of three polymers were intentionally introduced to polar bear feces, recovery rates averaged 79.3 ± 21.6% (n = 8), and Raman spectroscopy successfully identified all polymers in 87.5% of samples. The main study then investigated whether microplastics are present in polar bear feces in the Canadian Arctic. Colon feces (n = 15) and scat (n = 15) were collected from 30 polar bears through collaboration with Indigenous communities. Microplastics (polypropylene, polyethylene, and/or polyethylene terephthalate) were found in fecal samples from eight polar bears, although concentrations were low (<1 particle/g dry weight feces, on average). This study provides new information on plastics in Canadian bears and suggests fecal sampling can be utilized in community-based monitoring programs. M.E.S.
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