As the second most widely used plastic on the planet after polyethylene, the harms done to the environment and to human health by polypropylene is on an irreparable scale. Previous studies have reported the biodegradation of polypropylene when mixed with bioplastics or oxo-biodegradable plastics. However, the biodegradation of conventional polypropylene (that is, petroleum-based polypropylene which is not manufactured to be biodegradable) has not been reliably proven.
In this analysis, the shiitake mushroom Lentinula edodes was incubated for 150 days on 2cm by 8cm strips of polypropylene fabric taken from a filter of a surgical mask. Roughness of the strips' surface increased when observed under a microscope, and the strips' shear strength markedly decreased. These results indicate that L. edodes may posess the ability to biodegrade conventional polypropylene, although more research is necessary to validate the link between fungal activity and the changes seen in the polypropylene fabric.