The average person eats at least 50,000 particles of microplastic a year and breathes in a similar quantity, according to the first study to estimate human ingestion of plastic pollution.

The true number is likely to be many times higher, as only a small number of foods and drinks have been analysed for plastic contamination. The scientists reported that drinking a lot of bottled water drastically increased the particles consumed.

The health impacts of ingesting microplastic are unknown, but they could release toxic substances. Some pieces are small enough to penetrate human tissues, where they could trigger immune reactions.

Microplastic pollution is mostly created by the disintegration of plastic litter and appears to be ubiquitous across the planet. Researchers find microplastics everywhere they look; in the air, soil, rivers and the deepest oceans around the world.

They have been detected in tap and bottled water, seafood and beer. They were also found in human stool samples for the first time in October, confirming that people ingest the particles.

The new research, published in the journal Environmental Science and Technology, took the data from 26 previous studies that measure the amounts of microplastic particles in fish, shellfish, sugar, salt, beer and water, as well as in the air in cities.

The scientists then used US government dietary guidelines to calculate how many particles people would eat in a year. Adults eat about 50,000 microplastic particles a year and children about 40,000, they estimated.

Quick Guide Plastics and our throwaway society Show Why is plastic being demonised? Since the 1950s, 8.3bn tonnes of plastic has been produced. Plastic is seen as a versatile, indispensable product, but the environmental impact is becoming more stark. Plastic is now so pervasive that recycling systems cannot keep up and the leakage into the environment is such that by 2050 plastic in the ocean will outweigh fish. In 2017 scientists found plastic fibres in tap water, and plastic has been found in the stomachs of sea creatures in the deepest part of the ocean. Most plastic waste ends up in landfill sites or leaks into the natural environment, where it is causing huge damage to eco-systems on land and sea, creating near permanent contamination. According to academics in the United States, by 2015, of all the plastic waste generated since the 1950s, only 9% has been recycled, with 12% incinerated and 79% accumulated in landfill sites or the environment. Why are the supermarkets under fire? Producers of plastic include retailers, drinks companies and supermarkets. Supermarkets create more than half of the plastic waste in the household stream in the UK. But they refuse to reveal how much they put on to the streets and how much they pay towards recycling it. Supermarkets are under pressure to reduce their plastic packaging and campaigners argue they have the power to turn off the tap. Much of the packaging they sell to consumers is not recyclable: plastic film, black plastic trays, sleeves on drinks bottles and some coloured plastic. The Recycling Association and other experts believe supermarkets could do much more to make packaging 100% recyclable and reduce the use of plastic. Who pays to clean up the waste? The taxpayer, overwhelmingly. UK producers and retailers pay among the lowest towards recycling and dealing with their waste in Europe. In other countries, the “polluter” is forced to pay much more. In France, a sliding system of charges means those who put more non- recyclable material on the market pay more. What can shoppers do to help? Supermarkets are under pressure, not least from the prime minister, to create plastic-free aisles. A growing number of zero-waste shops are springing up and consumers are being encouraged to ask for products to be sold without plastic. Sandra Laville Photograph: ermingut/E+

Most food and drink types have not been tested, however, meaning the study only assessed 15% of calorie intake. “We don’t know a huge amount. There are some major data gaps that need to get filled,” said Kieran Cox, at the University of Victoria in Canada, who led the research.

Other foods, such as bread, processed products, meat, dairy and vegetables, may well contain just as much plastic, he said. “It is really highly likely there is going to be large amounts of plastic particles in these. You could be heading into the hundreds of thousands.”

Some of the best available data is on water, with bottled water containing 22 times more microplastic than tap water on average. A person who only drank bottled water would consume 130,000 particles per year from that source alone, the researchers said, compared with 4,000 from tap water.

Scientists do not know what happens when microplastics are inhaled, but the new study speculates that “most inhaled particles will be ingested” rather than coughed or sneezed out. The researchers also estimated that microplastic particles settling on to a single meal per day could add a further tens of thousands to the annual amount consumed.

Cox was clear that there are no known health effects as yet, but he said the ingested particles are “a high exposure risk in terms of numbers. It could be a potential alarm call for sure”.

Stephanie Wright, at King’s College London, who was not involved in the research, said: “These current estimates suggest microplastic exposure is relatively low compared to other particles. For example, it has been estimated that the average western diet exposes consumers to billions of titanium dioxide microparticles, a common additive, each day. However, what comparatively low microplastic exposures mean for health is unknown.”

The European commission’s chief scientific advisers said in a report in April: “The evidence [on the environmental and health risks of microplastics] provides grounds for genuine concern and for precaution to be exercised.”

They concluded: “Growing scientific evidence on the hazards of uncontrolled microplastic pollution, combined with its long-term persistence and irreversibility, suggests that reasonable and proportional measures should be taken to prevent the release of microplastics.”

Cox said his research had changed his own behaviour. “I definitely steer away from plastic packaging and try to avoid bottled water as much as possible,” he said.

“Removing single-use plastic from your life and supporting companies that are moving away from plastic packaging is going to have a non-trivial impact,” Cox said. “The facts are simple. We are producing a lot of plastic and it is ending up in the ecosystems, which we are a part of.”