The study, published April 26 in the journal Scientific Reports, is the first to connect microplastics in the ocean with land-based pathogens. It found that microplastics can make it easier for disease-causing pathogens to concentrate in plastic-contaminated areas of the ocean.
The pathogens studied — Toxoplasma gondii, Cryptosporidium (Crypto) and Giardia — can infect both humans and animals. They are recognized by the World Health Organization as underestimated causes of illness from shellfish consumption and are found throughout the ocean.
“It’s easy for people to dismiss plastic problems as something that doesn’t matter for them, like, ‘I’m not a turtle in the ocean; I won’t choke on this thing,'” said corresponding author Karen Shapiro, an infectious disease expert and associate professor in the UC Davis School of Veterinary Medicine. “But once you start talking about disease and health, there’s more power to implement change. Microplastics can actually move germs around, and these germs end up in our water and our food.”
A human and animal problem
Microplastics are tiny plastic particles smaller than 5 millimeters, no bigger than a grain of rice. They’ve contaminated waters as remote as Antarctica. The study’s findings indicate that, by hitchhiking on microplastics, pathogens can disperse throughout the ocean, reaching places a land parasite would normally never be found.
Microbeads and microfibers
For the study, the authors conducted laboratory experiments to test whether the selected pathogens can associate with plastics in sea water. They used two different types of microplastics: polyethylene microbeads and polyester microfibers. Microbeads are often found in cosmetics, such as exfoliants and cleansers, while microfibers are in clothing and fishing nets.
Co-author Chelsea Rochman, a plastic-pollution expert and assistant professor of ecology at the University of Toronto, said there are several ways humans can help reduce the impacts of microplastics in the ocean. She notes that microfibers are commonly shed in washing machines and can reach waterways via wastewater systems.
“This work demonstrates the importance of preventing sources of microplastics to our oceans,” said Rochman. “Mitigation strategies include filters on washing machines, filters on dryers, bioretention cells or other technologies to treat stormwater, and best management practices to prevent microplastic release from plastic industries and construction sites.”
Additional co-authors include Minji Kim, Lezlie Rueda, and James Moore of UC Davis, and Elizabeth VanWormer of University of Nebraska.
The study was funded by the Ocean Protection Council and California Sea Grant program, with student financial support provided by the UC Davis School of Veterinary Medicine Students Training in Advanced Research (STAR) program.
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