Microplastics Exposure Linked to Digestive, Reproductive and Respiratory Health Risks

Microplastics exposure has been linked to multiple health risks, including increased colon cancer risk, sperm and testicular damage, and injury or inflammation to the lungs, according to a recent report led by researchers at University of California San Francisco’s (UCSF) Program on Reproductive Health and the Environment and the Natural Resources Defense Council (NRDC).

Researchers analyzed nearly 3,000 recent studies, published between July 2022 and April 2024, that were focused on microplastics exposure and health. After reviewing the studies, the team narrowed their review to include 31 studies total, 28 of which focused on rodent subjects and three of which were human studies. Most of the studies evaluated health effects related to round microplastics made from polystyrene, while only one of the 31 studies focused on secondary microplastics, such as particles from vehicle tires.

In the review, researchers determined that microplastics exposure posed digestive tract, reproductive system and respiratory system hazards. Specific health threats could include risks of infertility, colon cancer, decreased lung function and chronic pulmonary inflammation, which in turn could increase lung cancer risks, UCSF reported. The authors published their findings in the journal Environmental Science & Technology.

Environ. Sci. Technol. 2024, 58, 52, 22843-22864

“These microplastics are basically particulate matter air pollution, and we know this type of air pollution is harmful,” said Dr. Tracey Woodruff, professor of obstetrics, gynecology and reproductive sciences at UCSF.

According to Reuters, humans could be ingesting about 5 grams of plastic per week, about the same weight as a credit card or a plastic cap of a bottle. While scientists have published thousands of studies on potential links between microplastics and health impacts, the extent of these potential hazards is still largely unknown.

Microplastics are pieces of plastic that are less than 5 millimeters in diameter. These plastics may be intentionally produced, such as in conventional glitter, or can be secondary microplastics, which are produced when larger pieces of plastic degrade when exposed to the elements. 

As Bon Appétit reported, microplastics can be found in bottled water, tap water, seafood, honey, produce, rice and tea bags. As plastic degrades in the environment, microplastics can also be released into the air from larger plastic pieces or even car tires. Previous studies have found evidence of microplastics in the human body, including the brain.

In response to the findings, the authors have recommended that governments increase policies to reduce microplastics pollution in the environment, including legislation that would ban intentionally added microplastics to products. Further, the organization has recommended more funding for additional research into microplastics exposure risks.

“We urge regulatory agencies and policy leaders to consider the growing evidence of health harms from microplastics, including colon and lung cancer,” said Nicholas Chartres, first author of the study, former lead of the science and policy team at the Program on Reproductive Health and the Environment, and a current senior research fellow at University of Sydney. “We hope state leaders will take immediate action to prevent further exposures.”