Exposure routes induce differential intestinal damage in zebrafish from polystyrene microplastics

Abstract

Microplastics (MPs) are ubiquitous in aquatic environments and are recognized as emerging pollutants due to their potential health risks to non-target organisms. Although the toxic effects of MPs on aquatic organisms have been extensively studied, the influence of exposure routes on these effects is often overlooked. This study comprehensively compared the impacts of waterborne and foodborne exposure to polystyrene MPs on intestinal accumulation and damage in adult zebrafish (Danio rerio). The findings demonstrated that MPs primarily accumulated in zebrafish intestines in a time-dependent manner, regardless of the exposure route. However, foodborne exposure led to a more rapid accumulation of MPs in the intestines than waterborne exposure. The accumulation and clearance potentials of MPs in zebrafish intestines was similar across both exposure routes. In silico modeling revealed that the accumulated MPs in the zebrafish intestine could closely bind to chymotrypsin, potentially impairing digestive function. Both waterborne and foodborne exposure induced significant intestinal structural damage, cell apoptosis, metabolic dysfunction, and alterations in microbial composition and function in zebrafish. Notably, foodborne exposure resulted in more severe intestinal damage, which may be correlated with the accelerated accumulation of MPs. Additionally, MPs were found to enhance pathogens while inhibiting probiotics in the intestinal flora, which could exacerbate intestinal risks, especially via the foodborne route. These findings highlight the higher health risk of MPs through trophic transfer, providing new insights into the control routes of MPs in aquatic environments, particularly in the context of increasing global MP pollution.