Tests on some of the world's leading brands of bottled water have found most contain tiny pieces of plastic.

Some 259 bottles from 11 brands in nine countries - Brazil, China, India, Indonesia, Kenya, Lebanon, Mexico, Thailand, and the US - were examined in research conducted at the State University of New York.

The study found 93% of the samples showed signs of microplastics, with an average of 10 plastic particles per litre, each larger than the width of a human hair.

Polypropylene, often used to make plastic bottle caps, was found to be the most common material (54%) with nylon being the second most abundant (16%).

The World Health Organisation has said it will launch a review into the potential risks of tiny plastic particles in bottled water.


The scientists in the study found "almost all (bottles) were contaminated to some degree".

Andrew Mayes, senior lecturer in chemistry at the University of East Anglia, and developer of the test method used, told journalism organisation Orb Media: "This is pretty substantial.

"I've looked in some detail at the finer points of the way the work was done, and I'm satisfied that it has been applied carefully and appropriately, in a way that I would have done it in my lab."

Image: The type of microplastic in bottled water, according to the study. PP - poloypropylene, PS - polystyrene, PE - polyethylene, PEST - polyester, polyethylene terephthalate. Pic: SUNY Fredonia

To reveal the plastic, each bottle was infused with a special dye that binds to plastic polymer before the dye was poured through a glass fibre filter.

When it was viewed through a microscope, under blue light and with the help of orange googles, the residue from each bottle could be seen.

The study has not been peer-reviewed or published in a scientific journal.

The study found roughly twice as many plastic particles in bottled water compared to tap water on average but the research also indicated that "at least some" of the contamination could be coming from the process of bottling the water - rather than the water itself.

Researchers said: "As polypropylene was the most common polymer found, the fragments could also be breaking off the cap, even entering the water through the simple act of opening the bottle."

A spokesperson for the World Health Organisation told Sky News: "We are aware of the study about microplastic in bottled water. Currently there is no evidence on impacts to human health.

"For WHO to make an informed risk assessment, we would need to establish that microplastics occur in water at concentrations that would be harmful to human health.

"Information on occurrence in water is very limited and there is no information on the impact to human health.

"While WHO continues to prioritise addressing known significant waterborne risks to health, we are aware that this is an emerging area of concern for consumers and member states.

"Thus WHO, as part of its continuous review of new evidence on water quality, would review the very scarce available evidence with the objective of identifying evidence gaps, and establishing a research agenda to inform a more thorough risk assessment."

A spokesperson from the Food Standards Agency, said: "Based on current information, including the evaluation on the safety of microplastics exposure from food undertaken by the European Food Safety Authority (EFSA), it is unlikely that the levels of microplastic particles reported in this study to be present in bottled water would cause harm to consumers.

"Microplastics are present in the environment, both on land and in water, therefore some presence in food is likely, but that doesn't necessarily mean that this presence is harmful. We will assess any emerging information concerning microplastics in food and drink."

:: Sky's Ocean Rescue campaign is trying to encourage people to stop using single-use plastics.