Pathogenic Hitchhikers on Microplastics: Ecological Risks and Gaps Gleaned from Two Decades of Research

Microplastics (MPs) are ubiquitous environmental contaminants that can serve as transport vehicles for pathogens, potentially spreading them into human settlements and posing a public health threat. In recent years, concerns have been raised about the potential hazardous effects of these “pathogenic hitchhikers” on human health. This review paper presents foundational information on pathogenic hitchhikers associated with MPs, based on a review of the literature published in scientific journals from 2000 to 2021. We used search engines such as Google Scholar and Mendeley to retrieve publications during those inclusive years. Over the past two decades, we identified only 57 published articles on human pathogenic microorganisms associated with MPs, underscoring this area of research as relatively novel and emerging. For the reviewed articles, the common polymer types associated with pathogens were polyethylene and polypropylene, while Vibrio spp. were the most commonly reported human pathogens present on MP surfaces. Albeit small in scale, these studies provide incontrovertible proof that MPs can act as vectors for disease spread and pose a threat to the ecosystem. Significant gaps, nonetheless, remain, particularly concerning their harmful effects on humans and other macro-organisms that may inadvertently ingest MPs harboring these ‘hitchhikers’. Addressing these gaps in future research is thus warranted to comprehensively understand the ecological roles and health risks posed by these hazardous contaminants on MPs and for informing relevant policy decisions.