American Scientist

Plastics, although incredibly useful, have become a global waste management issue. There's still a lack of a circular economy for plastic, so a large majority of it will be used only once before being discarded. Plastic debris can now be detected in the environment within freshwater lakes, rivers, and streams, where it can settle permanently into sediments or be transported into oceans. Another problem, says Imari Walker-Franklin of RTI International, is that plastic waste in the environment can undergo abiotic and biotic weathering that will cause fragmentation to the polymer and result in the release of microplastics and potentially hazardous chemicals. Some of these chemicals have been shown already to be toxic to humans—they can cause cell damage, cancer, or act has hormone mimics on body processes. 

Humans can also be exposed to microplastics in the air when they are near recycling facilities (where polyethylene is shredded) or when they are in close contact with recycled by-products (such as tire rubble used as mulch in recreational fields). Walker-Franklin discussed the risk of microplastics as an air pollutant in a talk on November 2, 2013, and discussed the role played by the physical characteristics of the inhaled particles, the ability of these small particles to release potentially hazardous chemicals, and the toxicological responses within the lungs.

A video of Walker-Franklin's talk is below, followed by highlights of the talk in the form of live social media from Science Communicators of North Carolina's intern Jasmine Johnson.