Bottled water may contain dangerous levels of microplastics that can slip through the body’s defences and lodge in vital organs—potentially increasing the risk of cancer, new research suggests.
The study, led by Sara Sajedi, a leading environmental management expert at Concordia University, found that people who regularly drink bottled water consume around 90,000 more microplastic particles each year than those who drink tap water.
The potential health effects of ingesting these microscopic fragments have been increasingly documented, with research linking them to chronic inflammation, oxidative stress, hormonal disruption, infertility, neurological damage and cancer.
Sajedi described the health risks posed by single-use plastic bottles as ‘serious’, and called for greater awareness of what she described as a ‘pressing issue.’
‘Education is the most important action we can take,’ she said. ‘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.’
Despite growing evidence of harm, scientists say the long-term effects of microplastic exposure are still poorly understood, largely due to a lack of standardised testing and global monitoring.
Microplastics are tiny plastic fragments measuring as little as two micrometres—about two-thousandths of a millimetre.
They make their way into food, water and even the air as plastic products degrade over time.
In bottled water, they form during manufacturing, storage and transport — meaning drinkers ingest them directly from the source, rather than through the food chain.
Recent studies have found microplastics in human lung tissue, placentas, breast milk and even blood, raising concern over how deeply they can penetrate the body.
A growing body of evidence has linked them to neurotoxicity, chronic inflammation and disruption of hormones and metabolism.
Writing in the Journal of Hazardous Materials, Sara Sajedi said: ‘They can also contribute to intestinal dysbiosis, disrupt the balance of gut bacteria, and may lead to respiratory diseases when inhaled.
‘These wide-ranging chronic health risks highlight the importance of recognising and addressing the impact of nano- and microplastics to safeguard human health.’
It comes after shocking new research earlier this week suggested that microplastics used in food packaging may be damaging the gut—raising the risk of bowel cancer and depression.
The discovery was made by Australian researchers who examined stool samples from healthy volunteers and found that microplastic particles could alter microbial activity in the gut.
Some of the changes mirrored patterns previously linked to depression and bowel cancer, suggesting the tiny fragments may disrupt the body’s internal balance in ways that affect both physical and mental health.
Experts called the findings ‘significant’, saying it was the first human study to show microplastics can alter the gut microbiome.
While scientists cannot yet say exactly why this happens, several theories are emerging.
One is that microplastics may carry chemical substances that interfere with bacterial metabolism, leading to changes in acid production in the gut.
Another is that harmful biofilms could form on the surface of microplastics, creating new ‘niches’ where certain microbes thrive, explained Mr Pacher-Deutsch, a microplastics researcher and lead author of the study.
However, researchers cautioned that further investigation is vital to understand precisely how microplastics cause such damage.
Meanwhile, Sara Sajedi is calling for a stronger regulatory approach to single-use plastic bottles. She says health authorities must ‘review relevant laws, policies and initiatives’ governing the production, distribution, use and disposal of disposable plastic products.
She also wants mandatory labelling to inform consumers about the presence of microplastics and their potential health effects and to hold manufacturers accountable for the entire lifecycle of their products.
‘Regulatory measures must be implemented to address environmental and health risks,’ she said, ‘ensuring a more sustainable and resilient future for water access.’
