First evidence of microplastic inhalation among free-ranging small cetaceans

Plastic is a ubiquitous environmental contaminant, resulting in widespread exposure across terrestrial and marine spaces. In the environment, plastics can degrade into microparticles where exposure has been documented in a variety of fauna at all trophic levels. Human epidemiological studies have found relationships between inhaled microplastics and oxidative stress and inflammation. Previous studies of bottlenose dolphins (Tursiops truncatus) have reported prevalent exposure to plasticizing chemicals (e.g., phthalates) as well as particle loads in gastrointestinal tracts, but exposure from inhalation has not yet been studied. The objective of this study was to determine if inhalation is a viable route of microplastic exposure for free-ranging dolphins. Exhalation samples were opportunistically collected from dolphins residing in Sarasota Bay, Florida (n = 5) and Barataria Bay, Louisiana (n = 6) during catch-and-release health assessments to screen for microplastic particles. All dolphin samples contained at least one suspected microplastic particle, and polymer composition was determined for 100% of a subset (n = 17) of samples. Additional studies are warranted to better understand the extent of inhaled microplastics, as well as to explore impacts, given potential risks to lung function and health.