Using an innovative technique, scientists counted an average of 240,000 detectable plastic fragments per liter of water after testing products from various popular brands.

This study, published in the journal PNAS, raises questions about potential health consequences.

"If people are concerned about nanoplastics in bottled water, it is reasonable to consider alternatives, such as tap water", said Beizhan Yan, a co-author of the study. However, he added: "We do not recommend not drinking bottled water when necessary, as the risk of dehydration may be greater than the potential consequences of exposure to nanoplastics".

Nanoplastics have increasingly attracted attention in recent years and are present everywhere on the planet.

Microplastics are less than 5,000 micrometers (5 millimeters), while nanoplastics are less than one micrometer. They are so small that they can enter the circulatory system and, therefore, even organs, including the brain and heart.

Research on their consequences for ecosystems and human health is still limited, but some studies have already highlighted harmful effects, for example, on the reproductive system.

Researchers used a new technique for this study, employing lasers.

They tested three water brands without revealing their names. "We believe that all bottled waters contain nanoplastics, so singling out some of them could be considered unfair", explained Beizhan Yan.

The results showed that each liter contains between 110,000 and 370,000 particles per liter, of which 90% turned out to be nanoplastics, with the rest being microplastics. The most commonly found type was nylon, likely originating from plastic filters used for water purification, followed by polyethylene terephthalate (PET), from which bottles are made.

In the future, researchers hope to test tap water, which also contains microplastics, but apparently in smaller quantities.