Plastic Debris As a Vector for Bacterial Disease: An Interdisciplinary Systematic Review

Pathogens and polymers can separately cause disease; however, environmental and medical researchers are increasingly investigating the capacity of polymers to transfer pathogenic bacteria, and cause disease, to hosts in new environments. We integrated causal frameworks from ecology and epidemiology into one interdisciplinary framework with four stages (colonization, survival, transfer, disease). We then systematically and critically reviewed 111 environmental and medical papers. We show 58% of studies investigated the colonization-stage alone but used this as evidence to classify a substratum as a vector. Only 11% of studies identified potential pathogens, with only 3% of studies confirming the presence of virulence-genes. Further, 8% of studies investigated μm-sized polymers with most (58%) examining less pervasive cm-sized polymers. No study showed bacteria can preferentially colonize, survive, transfer, and cause more disease on polymers compared to other environmental media. One laboratory experiment demonstrated plausibility for polymers to be colonized by a potential pathogen (Escherichia coli), survive, transfer, and cause disease in coral (Astrangia poculata). Our analysis shows a need for linked structured surveys with environmentally relevant experiments to understand patterns and processes across the vectoral stages, so that the risks and impacts of pathogens on polymers can be assessed with more certainty.