Gloves, masks, syringes, sampling tubes, plastic bags, plastic bottles, plastic wrappers, single-use vapes - these ubiquitous products are not only made of plastic but also designed for single-use. While plastic plays a vital role in our society, its exponential production, consumption, and uncontrolled disposal have given rise to challenging socioenvironmental issues. Among them, one critical question arises: does plastic waste pose a threat to public health?
It has been suggested that plastic waste, particularly in aquatic environments, can act as a vector for pathogens and facilitate the horizontal gene transfer of antimicrobial resistance genes. Numerous studies have focused on bacterial community profiling of the plastisphere (microbial communities inhabiting plastic surfaces that are distinctive from the surrounding environment), particularly through the analysis of the 16S RNA gene. Research has identified the presence of various genera associated with human diseases, such as Aeromonas, Arcobacter, Campylobacter, and Pseudomonas, in riverine plastics. This raises concerns about the transport of pathogen-enriched plastics, potentially disseminating harmful bacteria.
Furthermore, plastic-associated communities exhibit reduced taxonomic diversity compared to the surrounding waters. Loss of microbial diversity has been associated with increased disease transmission in other contexts, raising concerns about similar consequences in the plastisphere. It is key to conduct further research to establish whether the decreased microbial diversity on plastic waste increases a disease transmission risk. However, to date, there is a lack of clear evidence demonstrating pathogen presence and community structure and function on plastic waste as the cause for human infections.
To address this knowledge gap, researchers are exploring the use of MinIon technology for long-read sequencing and quantitative polymerase chain reaction (qPCR) for the detection of virulence genes, coupled with imaging analysis (e.g., Scanning Electron Microscopy) as potential avenues to better understand the structure and function of the microbial communities inhabiting plastic waste. Going further, and to ascertain if pathogens found in the plastisphere can indeed survive, transfer and cause infection after ingestion by seafood of colonised-plastic, studies are conducting exposure experiments.
Evidence on the risk of plastic waste as a vector for human disease, whether by direct contact or by consumption of contaminated produce, is key to further influencing industrial and governmental action. In countries where waste management systems are inadequate or non-existent, plastic waste often accumulates in waterways, potentially coming into direct contact with human waste. When floods occur, this plastic waste is mobilised, potentially leading to disease outbreaks. This warrants the question as to whether plastic pollution exacerbates the risks to human health in these situations, acting as a significant contributor to the spread of infectious diseases.
While it is easy to imagine the concomitant health and pollution problems that poorer countries face, a study off the Belgian coast reported the identification of human pathogens, including Escherichia coli, Bacillus cereus, and Stenotrophomonas maltophilia, on plastic debris that were not found in the surrounding water or sediment. These findings underscore the potential role of plastic waste as carriers of infectious agents.
To address this emerging public health concern, concerted efforts from academia, governments, industries, and individuals are necessary. Governments should prioritise the elimination and re-design of plastic products, and the development and implementation of robust waste management systems, ensuring appropriate disposal and recycling of plastic waste. Policies and regulations that encourage the use of eco-friendly alternatives and penalise excessive plastic production and disposal should be enacted.
While the direct impact of plastic waste on public health is yet to be fully understood, evidence suggests that plastic waste could act as a vector for pathogens and contribute to the spread of infectious diseases. It is then imperative that we address this emerging risk under the precautionary principle and a One-Health vision.