Feeding bottles may release microplastics during preparation of formula, a study has found © Philip Toscano/PA

Babies fed by bottle may be consuming millions of particles of microplastics every day

The consequences of microplastics on infant health are as yet unknown but any potential risks need to be urgently assessed, the researchers say.

Baby feeding bottles containing a type of plastic called polypropylene may release microplastics during the preparation of formula, a study carried out at the schools of engineering and chemistry at Trinity College Dublin has suggested.

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The research also indicated a strong relationship between heat and the release of microplastics, such that warmer liquids result in far greater release.

Researchers say annual production of polypropylene accounts for 20 per cent of non-fibre plastic production and it is the most widely used plastic in food preparation.

However, they add little is known about microplastic release from these types of containers.

Scientists tested microplastic release in 10 types of infant feeding bottles – representing the majority of the bottles found in the global online market – under World Health Organization-recommended sterilisation and formula preparation conditions.

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The feeding bottles were either made of polypropylene or included polypropylene-based accessories.

The study found that microplastic release varied between 1.3 to 16.2 million particles per litre among the bottles.

It also found the bottles continued to release microplastics over a 21-day test period and microplastic release varied according to different factors, such as water temperature.

However, the scientists cautioned there is not enough data on the consequences of microplastics on infant health and say they do not want to worry parents.

“When we saw these results in the lab we recognised immediately the potential impact they might have,” said Professor John Boland, of Trinity’s School of chemistry.

“The last thing we want is to unduly alarm parents, particularly when we don’t have sufficient information on the potential consequences of microplastics on infant health.

“We are calling on policymakers, however, to reassess the current guidelines for formula preparation when using plastic infant feeding bottles.

“Crucially, we have found that it is possible to mitigate the risk of ingesting microplastics by changing practices around sterilisation and formula preparation.”

In the study published in Nature Food, the authors used these data to model the potential global exposure of infants to microplastics.

They estimated that, on average, infants are exposed to 1.6 million microplastic particles per day during the first 12 months of life when fed using polypropylene-based bottles.

They also found the exposure modelling varied by region, with infants in Africa and Asia having lowest potential exposure while infants in Oceania, North America and Europe have the highest potential exposure.

The researchers concluded that infants may be exposed to higher levels of microplastics than previously thought.

They say more research is needed to understand how plastics that come into contact with food release microplastics during everyday use.

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“Previous research has predominantly focused on human exposure to micro and nanoplastics via transfer from ocean and soils into the food chain driven by the degradation of plastics in the environment,” said Professor Liwen Xiao, of Trinity’s school of engineering.

“Our study indicates that daily use of plastic products is an important source of microplastic release, meaning that the routes of exposure are much closer to us than previously thought.

“We need to urgently assess the potential risks of microplastics to human health.

“Understanding their fate and transport through the body following ingestion is an important focus of future research.

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“Determining the potential consequences of microplastics on our health is critical for the management of microplastic pollution.”

Reader Q&A: Are babies born with a sense of right and wrong?

Asked by: Luc Wallace, Canterbury

Early theorists in psychology mainly took the approach that babies are born without any sense of morality and have to learn it as they get older. We now know that although a fully developed sense of morality does not emerge until adolescence or later, babies already show signs of a rudimentary moral compass.

Consider a 2010 study by researchers at Yale University that involved babies as young as three months old watching a live ‘show’ of different shaped wooden blocks on a hill (the shapes corresponded to different characters, who either helped or hindered another character who was struggling to get up the hill). The researchers found that the babies preferred looking at the helpful characters, suggesting early preference for altruistic social behaviour.

Similar research with five-month-olds has shown that they have a sense of ‘justified retribution’: they prefer characters who hinder a previously obstructive individual rather than help them.

A sense of fairness also emerges early. In a study last year by researchers at the University of Washington, 13-month-old babies watched a researcher who distributed crackers fairly or unfairly among two other adults. When the infants were given a chance to interact with the researcher, they were more inclined to interact with a fair researcher than an unfair one, indicating that they had a preference for fairness.

Finally, a cute line of research has looked at babies’ inclination to respond to the needs of others, showing that already by age one they will offer comfort to a person who has hurt themselves, or try to help someone obtain an item that’s out of reach. The spontaneity of these behaviours has led scientists to believe that a sense of right and wrong is not entirely learned, but rather indicative of an evolved predisposition towards moral goodness.

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