Comparative evaluation of biodegradable microplastic presence in edible and non-edible tissues of cage-cultured and wild fishes of Periyar River

Abstract

Biodegradable plastics (BPs) are considered a promising alternative to conventional plastics; however, their biodegradation necessitates specific conditions and can persist in the environment for extended periods, posing toxicological effects on aquatic ecosystems and their organisms similar to conventional microplastics. The studies on biodegradable microplastics (BMPs) are limited and therefore, this study, aimed to evaluate the BMP presence in the gastrointestinal tract (GIT) and edible tissues of wild-caught and cage-cultured fishes of Periyar River, Kerala, India. Etroplus suratensis (n=300) and Oreochromis mossambicus (n=300) were collected from both sources. The study found BMPs in the GIT of all fishes sourced from cages and wild, with a higher but statistically insignificant abundance in wild fishes: 0.06±0.26 items/individual (0.01±0.00 items/g) in E. suratensis and 0.03±0.23 items/individual (0.01±0.01 items/g) in O. mossambicus. No BMPs were found in the edible tissues of cage-cultured fish, but they were detected in wild-caught fishes, i.e., 0.02 $$ 0.13 items/individual (0.02$$ 0.01 items/g) in E. suratensis and 0.01 $$ 0.11 items/individual (0.02$$ 0.01 items/g) in O. mossambicus. Poly (butylene adipate-co-terephthalate) (PBAT) and polylactic acid (PLA) were the only BMPs obtained in fish from both sources with the former being the dominant one. The potential annual average human exposure risk from the wild-caught fish was estimated from both fish species and the findings suggest children have a higher risk of exposure, i.e., 551 items/year followed by adults, i.e., 394 items/year and aged individuals, i.e., 239 items/year. The documented harmful impacts of BMPs on aquatic organisms, combined with the findings of this study, suggest the need for a thorough reassessment of BP production and disposal practices. Additionally, implementing robust monitoring systems is essential to food safety and public health.