There’s probably one lurking on your desk, kitchen top or bedside table.
But plastic water bottles are traps for nanoplastics — an umbrella term for the toxic particles that have been linked to cancer, fertility problems and birth defects.
A study this week revealed that the average one-litre bottle contains 240,000 pieces. For comparison the figure is just 5.5 per litre of tap water.
Invisible to the human eye, nanoplastics are between one and 1,000 nanometres in size, with 1,000 nanometres being equivalent to one hundredth of a millimetre.
They form when plastics break down into progressively smaller bits. They are so small and light that they are carried in the air around us and have been found infiltrating water, food and everyday products.
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As they are so tiny, they can pass through the intestines and lungs, directly into the bloodstream and to organs including the heart and brain.
They can even cross from the placenta to the bodies of unborn babies.
Researchers at the University of Columbia, who conducted the latest study, painstakingly identified and counted these minute particles in bottled water — detecting seven common plastics.
Results, published in the journal Proceedings of the National Academy of Sciences, revealed concentrations are up to 100 times greater than previously thought.
Polyethylene terephthalate (PET) and polyethylene (PE), plastics used to make bottles, were among the most common nanoplastics spotted.
They are thought to break down and get into water when bottles are squeezed or the lid is repeatedly opened and closed.
They can also seep into water if a bottle is exposed to heat, such left in a hot room, car on a warm day or outside in the sun.
However, most nanoplastics enter bottled water from the environment or the production process, with the scientists noting that plastic contamination has been detected ‘in every step from the well to the bottle’.
Polyvinyl chloride (PVC) was one of the most common and toxic nanoplastics detected in groundwater and bottled water.
This nanoplastic is thought to make its way into water sources as a result of plastic production, with 30million tons dumped in water or land every year.
On top of this, many products made with plastics, such as synthetic clothes, some tea bags and fishing nets, shed particles while being used.
Drinking water from a bottle could mean you are contaminating your body with tiny bits of plastic, which scientists fear can accumulate in your vital organs with unknown implications for health
During the bottling process, other variations, such as polypropylene, make their way into the product, according to the study
Rather than breaking down into harmless substances, plastic materials maintain their chemical composition as they divide into ever-smaller particles.
As a result, nanoplastics such as PVC makes their way into water sources.
During the bottling process, other variations, such as polypropylene (PP), make their way into the product, according to the study.
PP is widely used in equipment needed for manufacturing and as a coagulant aid — a process needed to remove hazardous materials from water.
Scientists also detected polystyrene (PS) in the bottled water they studied.
PS is the material used in water purification, removing harmful contaminants and replacing them with minerals — a process known as ion exchange.
Polyamide (PA), a type of nylon, was also detected in bottled water.
Researchers believe this, ironically, came from plastic filters water is passed through in a bid to purify it before being bottled.
PA is the most popular material used to make these filters.
However, these nanoplastics account for just 10 per cent of all those detected by the scientists, who admitted to having no idea what the other 90 per cent are.
Nanoplastics have worried scientists for decades and have been detected everywhere on Earth, from polar ice to soil and from drinking water to food.
Researchers are spooked, as the smaller things are, the more easily they can get inside us.
Previous studies have suggested that the average person ingests around five grams of plastic a week — equivalent to a credit card.
However, experts have warned that it may be much more, as not all foods have been analysed to check their plastic content.
People are also thought to breathe in up to 7,000 microplastics a day, prompting concerns they could rank alongside asbestos or tobacco as a health threat.
Plastic bottles especially have come under scrutiny for their contribution to nanoplastic intake, with experts even warning that pregnant women should avoid drinking from them after a study suggested that they can end up in the organs of foetues.
Nanoplastics don’t degrade in the body, leaving them to potentially cause inflammation and stress to cells.
While research into their effect on human health is in its infancy, animal studies have suggested the particles can cause inflammation, organ damage and affect reproduction, gut bacteria and metabolism.
Human studies have suggested that nanoplastics, specifically PVC, raise the risk of lung cancer, while research in mice has found a link between PS and ovarian cancer.
