Microplastics: A Global, Multi-Media Concern

Plastics are increasingly used in Global Society. Their low cost incentivizes careless disposal & their entry into the marine environment is projected to double in 10 years. Polymers eventually fragment, as a function of composition & environmental factors, into microplastics. These take the form of irregular particles or fibers, with sizes extending down into the nanoparticle range. Microbeads are also intentionally manufactured. Small particle size accentuates reactive surface areas & analytical difficulties. While the impacts of large debris on charismatic mega-fauna have been recognized for decades, concern over threats from microplastics is recent. Smaller fragment size places minute, but ecologically important organisms at risk. Microplastics also present threats to humans, where exposure is likely greatest from inhalation & ingestion of indoor dust, not seafood consumption. Chemicals are added to plastics at % levels during manufacturing to achieve desired properties. Additives include flame retardants, which pose particular risks to children. Environmental pollutants also concentrate on polymer surfaces. In aquatic organisms filter feeders ranging from oysters to whale sharks may be at particular risk from physical & chemical impacts. Plastic debris may also serve as novel substrates for aquatic biofilms & their transport may carry exotics substantial distances. Wastewater treatment removes >90% of microplastics from effluents, but these may later be reintroduced to the environment by land application.