Research highlights microplastics risks in bottled water
A new study warns that single-use plastic water bottles release nano- and microplastics that pose chronic health risks. Led by Sarah Sajedi at Concordia University, the research estimates bottled water drinkers ingest up to 90,000 more particles annually than tap water users. These tiny pollutants can enter the bloodstream and affect vital organs, leading to inflammation and other issues.
Sarah Sajedi's journey into plastic waste research began on the beaches of Thailand's Phi Phi islands. While gazing at the Andaman Sea, she noticed water bottles littering the sand, prompting her to shift from a business career to a PhD at Concordia University. As co-founder of ERA Environmental Management Solutions, Sajedi brought expertise in environmental management to her studies.
Her latest review, published in the Journal of Hazardous Materials in 2025, analyzes over 140 scientific articles on the health dangers of single-use plastic water bottles. On average, people ingest 39,000 to 52,000 microplastic particles yearly, with bottled water consumers facing an additional 90,000 particles compared to those using tap water. Microplastics range from 1 micron to 5 millimeters, while nanoplastics are smaller than 1 micron. These particles shed during manufacturing, storage, transport, and breakdown, especially from low-quality plastics exposed to sunlight and temperature changes.
Once ingested, the particles can cross biological barriers, enter the bloodstream, and reach organs, causing chronic inflammation, oxidative stress, hormonal disruption, impaired reproduction, neurological damage, and various cancers. Long-term effects are unclear due to inconsistent testing methods and a lack of standardized detection. Sajedi notes challenges in measurement: some techniques identify small particles but not composition, others detail makeup but miss tiny ones, and advanced tools are expensive.
Co-authors Chunjiang An and Zhi Chen from Concordia's Department of Building, Civil and Environmental Engineering contributed to the paper, supported by the Natural Sciences and Engineering Research Council of Canada and the university. Sajedi praises global efforts to curb plastic waste like bags and straws but highlights the gap in addressing water bottles. "Education is the most important action we can take," she says. "Drinking water from plastic bottles is fine in an emergency but it is not something that should be used in daily life. People need to understand that the issue is not acute toxicity -- it is chronic toxicity."