Plastics May Be Fueling Antimicrobial Resistance, New Study Warns

A recent Journal of Hazardous Materials study highlights critical links between plastic pollution and the global rise in antimicrobial resistance (AMR), a new public health concern. Scientists from Plymouth Marine Laboratory and the University of Exeter have found various points in the lifecycle of plastics that could be causing drug-resistant microbes to be transmitted and develop, prompting more concerted action across environmental, health, and climate sectors.

Plastic pollution, antimicrobial resistance, and climate change are all major worldwide issues, but attempts to minimize them are usually siloed. Over 376 million metric tonnes of plastic were created globally in 2020 alone—and nearly a quarter of that was not properly managed—so there are increasing worries about the long-term impacts of plastics on the environment. Since plastic is very resilient, it remains in environments for hundreds of years, increasing the chances of exposure to microbes and chemicals. Simultaneously, antimicrobial resistance develops on, which led to nearly 4.95 million fatalities globally in 2019. AMR has the potential to become the leading cause of death by 2050 if left unmanaged.

The study explains how various stages in the life cycle of plastic—from sourcing raw materials to disposal—interact with microbial communities and introduce elements that can cause resistance. The starting point of the life cycle of plastic involves fossil fuels like crude oil and natural gas, which are usually transported by biocide-treated pipelines. Such biocides used to kill biological contaminations have the side effect of promoting AMR as they enable resistance bacteria to thrive. Spillage of crude oil has also been associated with the proliferation of resistant bacteria in the environment and even wildlife as studies have revealed that dolphins exposed to contaminated water had more multidrug-resistant bacteria than in clean waters.

In the manufacturing process, several additives—plasticisers, stabilisers, and biocides—are used to improve plastic characteristics. Such chemicals, often not chemically bound to the plastic, can migrate into the environment. Hundreds of such additives have been registered as hazardous by the European Chemicals Agency. Notably, such chemicals as triclosan and heavy metals used in packaging plastic are known to enable the evolution of AMR through co-selection—where resistance to one drug causes resistance to others. For example, exposure to leachate from polyvinyl chloride (PVC) plastic into seawater has been noted to enrich infection genes and resistance genes. Other plastics which are also used comparatively very often like bisphenols and phthalates also allow transfer of genes between bacteria, thereby enabling the transfer of AMR.

After processing plastics into final consumer products, other risks are presented through human exposure. Heavy metals and other chemicals leach from packaging materials into foodstuffs, especially when cooked, increasing the likelihood that such chemicals will disrupt gut microbiota or respiratory function. For instance, antimony, which is popular in plastic bottles, is capable of turning into more than tolerable contamination levels and leading to treatment failures attributed to resistance.

Waste collection, being another stage of the life cycle of plastic, is also an issue. Waste handlers may have increased exposure to AMR microbes. If hospital waste is mixed with general waste, genes of resistance can spread via biofilms on plastic surfaces. Preventive actions like ongoing surveillance and use of PPE are advisable to reduce such exposure.

Disposal methods, particularly landfill usage, have been shown to be AMR bacterial and gene hotspots. Landfills are also likely to contain a mixture of antibiotics, personal care items, and heavy metals, all of which have the potential to support AMR proliferation. During episodes of intense rains, these contaminants will filter into adjacent soils, aquifers, and agricultural lands, creating reservoirs for resistant bacteria. These are immediately threatening communities that rely on these resources for water, food, and livelihood.

Recycling, although intended to stem plastic waste, also carries risks. Studies show that recycled plastics contain higher concentrations of metals, which can mean higher co-selection of AMRs. Recycling is done with the aid of washing chemicals and disinfectants that ultimately remain in waste water and affect microbial communities. Plastics made from waste domestic material that has previously been contaminated may thus prove to be more toxic than freshly manufactured ones.

The study also identifies the "Plastisphere"—distinct microbial assemblages which infest plastic debris. These can include pathogens, as well as resilient microbes, which are transported to new areas, consumed by wildlife, or washed up on beaches, hence increasing human exposure. Moreover, pandemics like COVID-19 have contributed towards the use of single-use plastics for personal protective equipment, increasing levels of pollution and, subsequently, potentially strengthening the AMR loop.

The review identifies key questions for research in the future, including to what extent biocides used in oil production is a cause of AMR, the impact of crude oil spills, the risk posed by plastic additives, and the consequences of leaching heavy metals from food packaging. An understanding of these processes could underpin interdisciplinary responses ranging from sustainable alternatives to plastics to concerted global surveillance

Source:
Plymouth Marine Laboratory | Journal of Hazardous Materials (2025), DOI: 10.1016/j.jhazmat.2025.138700