Microplastics can now be found in almost every environment on Earth, but scientists know surprisingly little about how the products we use every day shed these tiny plastic particles. Bottle-fed babies may ingest more than a million pieces of microplastics each day, new research showed Monday highlighting the abundance of plastics in our food products.

There is growing evidence that humans consume huge numbers of the tiny particles, formed when larger pieces of plastic break down, but very little is known about the knock-on health consequences. Researchers in Ireland looked at the rate of microplastic released in 10 types of baby bottles or accessories made from polypropylene, the most commonly used plastic for food containers.

The researchers in Ireland found that at an average bottle-fed baby consumed 1.6 million plastic microparticles each day during the first 12 months of their lives. The research was published in the Nature Food journal. Research had earlier concluded that microplastics and nanoplastics have been found in humans worldwide. According to “Plastic Oceans”, at least 300 million tonnes of plastic waste is produced worldwide every year with microplastics being 0.2 inches and nano plastics smaller than 0.001 mm. Scientists found that the recommended high-temperature process for sterilising plastic bottles and preparing formula milk (heating milk, with cerelac or crushed biscuits) caused bottles to shed millions of microplastics and trillions of even smaller nanoplastics. The heating procedure leads to a greater release of the minuscule fragments. Micro (and even tinier nano) plastics are released into our food and water systems through the breakdown of larger plastic waste.

The researchers involved were from AMBER, the SFI Research Centre for Advanced Materials and Bioengineering Research, TrinityHaus and the schools of engineering and chemistry at Trinity College Dublin. They followed official guidelines from the World Health Organization on sterilization and formula preparation conditions. Over a 21-day test period, the team found that the bottles released between 1.3 and 16.2 million plastic microparticles per litre. They then used this data to model the potential global infant exposure to microplastics from bottle-feeding, based on national average rates of breastfeeding.

The authors noted that it was in developed nations that babies were likely ingesting the most plastic – 2.3 million particles daily in North America and 2.6 million in Europe. This was attributed to relatively low breast-feeding rates in richer countries. They said the levels could easily be lowered by taking a few additional steps, including rinsing bottles with cold sterilized water and preparing formula milk in a non-plastic container before filling the bottle.

Earlier, a study by Arizona State University had claimed that tiny particles of plastic exist in human tissues in lungs, liver, spleen and kidneys with microplastics being the most common.