Microplastic-Mediated Delivery of Di-butyl Phthalate Alters C. elegans Lifespan and Reproductive Fidelity

Microplastics harbor chemical additives and absorb pollutants from the environment. Microplastics pose a human health threat and have been found in nearly all human tissues. The toxicological pathways and physiological effects of microplastic-mediated chemical exposure following ingestion remain unknown. Here we use <i>Caenorhabditis elegans</i> to investigate the effects of di-butyl phthalate and polystyrene microplastic mixtures on fertility and lifespan. Our studies demonstrate that 1 μm microplastics at 1 mg/L exposure levels result in decreased brood size, whereas 1000 times fewer microplastics (1 μg/L) did not affect the number of eggs laid. While there was no change in brood size at 1 μg/L microplastic exposure levels, there was an increase in embryonic lethality. Microplastics-mediated delivery of di-butyl phthalate to <i>C. elegans</i> significantly reduced brood size and increased embryonic lethality compared to exposure to microplastics alone. This reproductive toxicity is potentially due to a stress response via DAF-16, as observed with microplastics and di-butyl phthalate co-exposure. Furthermore, chronic exposure (from hatching onward) to microplastics shortened the lifespan of <i>C. elegans</i>, which was further reduced with di-butyl phthalate co-exposure. The exacerbated defects observed with co-exposure to phthalate-containing microplastics underscore the risks associated with microplastics releasing the additives and/or chemicals that they have absorbed from the environment.