Synthetical effect of microplastics and chiral drug amphetamine on a primary food source algae Chlorella pyrenoids

The biological effects and fate of the chiral illicit drug amphetamine in the presence and absence of microplastics on freshwater algae (Chlorella pyrenoids), including acute toxicity, growth inhibition, photosynthetic pigment content, oxidative stress, lipid peroxidation, and enantioselective fate were assessed. An agglomeration and the shading effects of microplastics in algae suspension were also determined. Microplastics were observed to in-crease the toxicity of amphetamine to algae and reduce algae cell growth. Exposed Chlorella pyrenoids exhibited a reduced algae cell counts in an agglomeration test, wherein algae cells decreased between 18% and 56% among treatment groups exposed to 5-50 mg L-1 of microplastics. The agglomeration test suggested that microplastics might significantly increase the adverse effect on algae. Furthermore, our experiments demonstrated enantio-selective degradation of amphetamine in algae, and demonstrated that the S-enantiomer was preferably degraded by algae cells. Adding microplastics to the algae suspension significantly reduced the enantiose-lectivity, with an EF value of 0.41 compared with amphetamine-alone group (0.34) after 21 d exposure. These results demonstrated the first evidence of microplastics acting as a vehicle to enhance amphetamine toxicity to Chlorella pyrenoids, as well as provided new insights into the co-effect of microplastics and organic contaminants on food source.

Automated summary

This study assessed the biological effects and fate of the chiral illicit drug amphetamine on freshwater algae in the presence and absence of microplastics. The results showed that microplastics increased the toxicity of amphetamine to algae and reduced algae cell growth. The study also demonstrated enantioselective degradation of amphetamine in algae, with the S-enantiomer being preferred. Adding microplastics to the algae suspension reduced the enantioselectivity.