Many infants are given the bottle in addition to or instead of the mother’s breast. But now an experiment has revealed that the recommended preparation of bottled milk releases considerable amounts of microplastic from the plastic of the bottle. The polypropylene in a baby bottle can release up to 16 million microplastic particles and billions of nanoparticles into the liquid per liter. The hotter the water that is filled in, the higher the release of these plastic particles, as the researchers report. They estimate that an infant in Europe and North America ingests an average of more than two million microplastic particles per day.
Plastics have long been ubiquitous in our everyday lives because they are versatile and inexpensive. But the consequences are huge amounts of plastic waste and microplastics that end up in the environment and pollute the oceans, water bodies, soil and even the air. Studies also show that plastic particles, which are between a few micrometers and five millimeters in size, are also found in our food and beverages. According to estimates, each person ingests around 100,000 such particles per year – through drinking water, breathing air, but also through the consumption of fish, seafood or honey. Researchers have also detected microplastics in human stool. The widely used plastic polypropylene had the largest share of the particles in the feces. So far, however, there is no comprehensive overview of how and from where people ingest microplastics everywhere.
Up to 16 million microplastic particles per liter
Dunzhu Li from the AMBER research center at Trinity College in Dublin and his team are now making a contribution. You have investigated whether and how much microplastics are released when vials are used for feeding babies. “These baby bottles are mostly made of polypropylene and are regularly exposed to hot water and intensive shaking when the bottle milk is being prepared,” the researchers explain. The World Health Organization (WHO) recommends rinsing the vials first with boiling water and then mixing the milk powder with water at at least 70 degrees Celsius in order to keep the germ load as low as possible. Based on this recipe, Li and his team first filled ten common baby bottles made of polypropylene with boiling water, then 70 degrees Celsius, and then determined the amount of plastic particles in the water using laser spectroscopy and atomic force microscopy.
The analyzes showed a strong release of microplastics from all vials. The determined concentrations were between 1.3 and 16.2 million microplastic particles per liter. This is considerably more than the usual values of up to 1000 particles per liter for drinking water and therefore speaks for the polypropylene of the vials as the source of contamination, the researchers write. The high values remained similarly high even after three weeks of regular use of the vials. As Li and his team explain, their values are likely still grossly underestimated. Because nanoparticles below 0.8 micrometers were not captured by their filters. In additional analyzes of random samples of baby bottle water, however, they found trillions of around 100 nanometer nanoparticles per liter. Overall, almost two thirds of the registered particles were smaller than 20 micrometers.
The scientists have calculated for 48 countries what this release of microplastics will mean for infants worldwide. The basis of the contamination determined in their experiment, the average daily milk intake of an infant, the respective market share of polypropylene baby bottles and the proportion of mothers who do not breastfeed their infants but feed them in bottles. “We have found that an infant ingests around 1.58 million plastic particles per day on average worldwide through bottle-feeding,” report Li and his colleagues. However, the amount varies greatly depending on the region: In the countries of Asia and Africa, where more mothers breastfeed their children, the contamination is lowest with a good 500,000 to almost 900,000 particles per day. In Europe, North America and Oceania, on the other hand, it is the highest with 2.1 to 2.6 million microplastic particles per infant per day.
Better to stir milk outside of the bottle
According to the researchers, one of the main reasons for the heavy contamination of the baby bottle contents is the high temperature to which the plastic is exposed during the preparation of the bottle milk. “The sterilization recommended by the WHO in particular increases the release of microplastics,” said Li and his team. If, on the other hand, the baby milk is mixed at lower temperatures, the exposure is reduced, as additional tests have shown. The scientists therefore recommend letting the vials cool down with boiling water after sterilization and then rinsing them three times with cold, boiled water. The milk should also be mixed with water at 70 degrees Celsius in a non-plastic container and only then poured into the bottle. The researchers advise against rewarming the already mixed bottled milk in the microwave or in the bottle.
“We have to accept that plastics permeate our modern life and that they release micro- and nanoplastics when used every day,” says Li. However, the researchers emphasize, the sheer amount of microplastic particles does not say anything about whether and how harmful this is for the health of children and adults. “The last thing we want is to cause unnecessary panic in parents,” says Li’s colleague John Boland. “Because so far we simply do not have enough information about the potential effects of microplastics on the health of young children.” Hanns Moshammer, an environmental doctor from the Medical University of Vienna, who was not involved in the study, sees it similarly: “There is still a need for research. There is probably a grain size at which the absorption of microplastics from the intestine is relevant or possible, ”he says. “With a healthy baby, however, based on the current state of knowledge, I would not assume a particularly relevant recording. I would be more concerned about nanoplastics. But then we come up against the limits of our detection methods. “
Source: Dunzhu Li (Trinity College, Dublin) et al., Nature Food, doi: 10.1038 / s43016-020-00171-y