Microplastics Could Be Spreading Dangerous Pathogens, Scientists Warn
Researchers are actively assessing how widespread microplastic pollution is and what it could mean for human health. A recent study identifies several downstream health risks as these tiny fragments move through ecosystems.
Evidence suggests microplastics themselves can harm biological systems, and they’re known to soak up other toxic pollutants. Now, new findings from the University of Exeter and the Plymouth Marine Laboratory in the UK show that microbes also form biofilms on microplastics. These biofilms—often called plastispheres—can shelter harmful bacteria and support their growth and survival, meaning microplastics might help disseminate pathogens and antimicrobial resistance (AMR).
Relatedly, there is research linking microplastics to worsening Alzheimer’s symptoms in mice, underscoring broader health concerns. The potential hazards span from pathogenic bacteria entering the food chain to the accelerated spread of drug-resistant bacteria that complicate treatments and increase medical risks.
“Our results indicate that microplastics can act as carriers for dangerous pathogens and antimicrobial-resistant bacteria, boosting their persistence and spread,” notes Pennie Lindeque, a marine scientist at the Plymouth Marine Laboratory. “This interaction poses a rising threat to both the environment and public health and demands urgent action.”
To explore these dynamics, researchers submerged strands of tiny plastic pellets used in manufacturing and water treatment, along with similar 4 mm polystyrene fragments, at four sites along England’s Truro river system. The sites were selected to reflect a range of water quality levels, influenced by proximity to a wastewater treatment plant and a hospital. In addition to plastics, researchers tested small beads of glass and wood and plastic bio-beads intended to support beneficial bacteria for water purification. When these bio-beads escape treatment plants and reach rivers, they can cause problems, as observed in prior studies.
After two months, the team analyzed the bacteria attached to each material. They found that site-specific water quality more strongly shaped the bacterial communities than the material itself, but several issues with plastics emerged. Biofilms on microplastics carried substantially more genes associated with drug resistance than those on wood or glass. In addition, harmful groups such as Flavobacteriia and Sphingobacteriia were more prevalent on microplastics downstream of hospitals and wastewater facilities, even when these bacteria were not abundant in the surrounding water.
“These findings indicate that microplastics aren’t just an environmental nuisance—they may facilitate the spread of antimicrobial resistance,” says microbiologist Aimee Murray from the University of Exeter. “That’s why we need coordinated, cross-sector strategies to reduce plastic pollution and protect both environmental and human health.”
The researchers plan to expand their sampling network and test a wider array of environmental conditions to better understand potential impacts. They also advocate for preventing plastics — including bio-beads — from entering the environment in the first place.
Beyond toxicity, microplastics’ role as breeding grounds for bacteria highlights risks for both humans and wildlife wherever plastic accumulates. Marine scientist Emily Stevenson of the University of Exeter adds, “This work reveals the diverse and sometimes harmful bacteria that colonize plastic in the environment. We therefore recommend gloves for beach-cleaning volunteers and thorough hand-washing afterward.”
The study appears in Environment International.
