What an infant meets first

The bottle

Up to 16.2 million particles per litre released by polypropylene feeding bottles during formula preparation

Li and colleagues prepared formula in polypropylene feeding bottles and counted what came off. Release ran as high as 16.2 million particles per litre. Sterilising the bottle and using hotter water both raised it, and a 21-day run of the same bottles showed the release rising and falling rather than tailing off.

What changes it. Water temperature and the sterilising step both moved the count in their data. Neither is a step to drop, and the study is about the plastic, not the hygiene. Across 48 regions the modelled intake for a bottle-fed infant ran from 14,600 to 4.55 million particles a day.

Sources: Li 2020

The teat

About 660,000 silicone-derived particles a bottle-fed baby could swallow from steam-sterilised teats by its first birthday

Su and colleagues steam-sterilised silicone rubber teats and examined the surface and the wash water under optical photothermal infrared microscopy. Steam etched the surface, and the water carried flakes and oil-film shaped particles from 0.6 to 332 micrometres, made of the silicone base and its polyamide additive. Their estimate for a baby's first year came to more than 0.66 million particles, about 81 percent of them between 1.5 and 10 micrometres.

What changes it. A modelled first-year figure built on the measured release per steaming, and the authors say the health risk of the particles is unknown. Silicone is outside the polymer libraries most of the other studies on this page used, so it is missing from their figures.

Sources: Su 2022

The formula tin

30 of 30 infant formula products contained microplastic, about 49 particles a day for an infant fed only formula

Kadac-Czapska's team isolated and identified particles in thirty infant formula products. Every product carried microplastic, mostly polyamide, polyethylene, polypropylene and PET, as fibres, fragments and films. Their estimate for an infant fed only formula was about 49 particles a day, give or take 32.

What changes it. This is the powder before it meets a bottle. The tin comes to tens of particles a day; Li's modelled bottle intake runs from fifteen thousand to over four million a day, counted down to a smaller size. On that axis the container outweighs the contents.

Sources: Kadac-Czapska 2024

The breast milk

23 of 59 breast milk samples carried microplastic under Raman microspectroscopy

Saraluck and colleagues analysed postpartum breast milk from 59 women by Raman microspectroscopy. Twenty-three samples, 39 percent, carried microplastic, mostly polypropylene, polyethylene, polystyrene and PVC. A Rome study two years earlier found it in 26 of 34 samples.

What changes it. The Rome study found no link to any habit of the mother's; the Thai study found hygiene practices differed between the women with and without particles, without naming one. Neither weighs the count against the bottle. Breast milk is on this page because it has been measured, not because it is the larger source.

Sources: Saraluck 2024 · Ragusa 2022

What nobody has measured

What a bottle-fed infant actually swallows. Every daily figure at this stop is modelled from what a bottle, a teat or a tin of powder gave up in a lab. One pilot, at the next stop, holds a feed and the same infant's stool side by side, and with eighteen pairs it could not say which particle came from which.

The newborn's first nappy

80 particles counted in the meconium of nine newborns, against 34 in their placentas and 14 in cord blood

Zhu's team recruited nine mother and infant pairs in South China and read placenta, cord blood and meconium by micro-Raman spectroscopy. They counted 80 particles in the meconium, 34 in the placentas and 14 in the cord blood, of 14, 9 and 4 polymer types. More than 80 percent were 100 to 400 micrometres. Meconium forms before birth, so everything in it arrived before the first feed.

What changes it. Nine pairs, and a count rather than a concentration. A larger placenta study from New Mexico, 62 specimens weighed by pyrolysis, found polymer in every one at 6.5 to 685 micrograms per gram.

Sources: Zhu 2024 · Garcia 2024

Another first nappy, counted again

0 of 16 meconium samples carried any particle above 10 micrometres under strict contamination control

Li's team analysed 16 meconium samples by infrared microspectroscopy after developing a digestion method that recovered particles without destroying them. They found no microplastic above 10 micrometres in any sample, and read the gap between their result and earlier studies as a warning about contamination during collection and analysis.

What changes it. Two labs, two answers. A nursery figure from a handful of samples is only as good as the blank controls behind it, and a study that reports none deserves the same weight as a study that reports some.

Sources: Li 2023

The nappy at one year

36,000 nanograms of PET per gram of stool from six one-year-olds, against 2,600 in ten adults

Zhang and colleagues measured PET and polycarbonate in stool from six one-year-olds, three meconium samples and ten adults from New York State. Every infant sample carried PET, a median of 36,000 nanograms per gram against 2,600 in adults. Per kilogram of body weight, the estimated daily intake ran about fourteen times higher in the infants.

What changes it. Six infants and ten adults, two polymers. The authors point to bottles, teethers and toys as the likely difference; the study measured none of them. Liu's pilot, 18 mother and infant pairs with stool, breast milk and formula sampled at six months, found sixteen polymer types across them and read breastfeeding, feeding bottles and plastic toys as the likely infant-side sources.

Sources: Zhang 2021 · Liu 2023

The changing mat

22 to 6,169 fibres settling per square metre per day in 32 Sydney homes

Soltani's team left glass dishes out in 32 Sydney homes for a month and analysed what settled. Deposition ran from 22 to 6,169 fibres per square metre per day. Ninety-nine percent of the dust was fibres, 39 percent of those petrochemical, and homes with carpet as the main floor covering collected more polyester, polyamide and acrylic.

What changes it. A flat surface at cot height collects the same fall, and the flooring sets what is in it. In their model the highest inhalation rate of any age fell on infants under six months, at 0.31 milligrams per kilogram a year.

Sources: Soltani 2021

What falls from the air

108 homes in 29 countries, and the highest modelled dose of any age group fell on infants under two

Soltani's group then collected a month of settled dust from 108 homes in 29 countries and read it by microscopy and infrared spectroscopy. Synthetic polymers led in both high and low income countries, polyamide and polyester fibres most of all in the richer ones, and the sources traced mostly to indoors. Modelled by inhalation and by ingestion, infants from birth to two took the highest dose per kilogram of body weight.

What changes it. Across every income band, homes vacuumed more often carried lower loads. The dose is modelled from the dust; nobody in the study sampled an infant.

Sources: Soltani 2022

What nobody has measured

Whether the newborn counts are real. Two labs read meconium and got opposite answers, and no study large enough, with blank controls strict enough, has settled which was right.

The rug

5,900 micrograms of PET per gram of house dust, the median across 286 samples from 12 countries

Zhang and colleagues measured PET and polycarbonate in 286 indoor dust samples from 12 countries. PET turned up in every sample, from 38 to 120,000 micrograms per gram with a median of 5,900. From those concentrations they put the median daily PET intake for infants at 4,000 to 150,000 nanograms per kilogram of body weight.

What changes it. The intake is modelled from the dust and an assumed hand to mouth rate. Flooring sets the dust: the Sydney study a stop back found the polyester and polyamide fibres tracking carpet.

Sources: Zhang 2020

The play mat

2 to 3 times more microplastic off a play mat after UV sterilising than after chlorine bleaching

Ou's team disinfected play mats of four polymers by chlorine bleach, UV and UV with bleach, then counted what came off. Every treatment raised the release, and UV sterilising and UV bleaching freed two to three times as much as chlorine bleaching. PET mats shed most, then polypropylene and polyethylene, then PVC. The same treatments also raised the volatile compounds coming off, from 1.82 to 15.82 milligrams per square metre of polyethylene mat under UV bleaching.

What changes it. The disinfectant is the larger lever and the mat's polymer the smaller one. The authors' own conclusion is that chlorine bleaching frees the least.

Sources: Ou 2025

The building bricks

Several thousand microplastics per square millimetre of scratched brick after simulated play, and several hundred thousand nanoplastics

Luo's team identified the plastic in toy building bricks as ABS or polycarbonate by Raman spectroscopy, then simulated play and looked at the scratches under an electron microscope. The scratches were the source: the estimate was several thousand microplastics and several hundred thousand nanoplastics per square millimetre of scratched surface.

What changes it. Per square millimetre of scratch, not per brick or per hour of play, so the figure cannot be turned into a dose. The colourants in the bricks interfered with the analysis, which the paper discusses.

Sources: Luo 2024

The straw cup

1.2 nanograms of polypropylene per kilogram of body weight a day for a toddler after 100 sips from a plastic straw cup

Burhani's team stored water in toddlers' reusable plastic straw cups, then abraded them the way a child draws on and bites a straw, and read the water by laser direct infrared imaging. Polypropylene particles of 20 to 50 micrometres were there every time; nothing from the silicone straw was, within the method's range. Their exposure model put a toddler's daily polypropylene intake at 1.2 nanograms per kilogram after 100 sips.

What changes it. A mass figure, and a small one, from a cup that gives up 20 to 50 micrometre polypropylene when a toddler chews the straw. The authors tie the release to stress on the bottle, which is what a toddler supplies.

Sources: Burhani 2026

The playground outside

72 particles per gram of sand inside 19 Los Angeles playgrounds, more than five times the level elsewhere in the same parks

Koutnik's team sampled sand, soil and leaves from 19 playgrounds in Los Angeles parks. Sand inside the playgrounds averaged 72 particles per gram, over half of it polyethylene or polypropylene, and more than five times the concentration outside the playground in the same park. The polymer mix inside the playgrounds resembled the plastic structures in them, which the authors offer as one contributor.

What changes it. Population density tracked the park soil slightly and the playground sand not at all, which points at the equipment rather than the city. Hand to mouth and inhalation are the routes the authors name.

Sources: Koutnik 2023

What nobody has measured

How much of a floor an infant swallows. The rug figure at this stop is a model built from a dust concentration and an assumed hand to mouth rate, and the straw cup's from a release per sip. Nobody has measured the particles in an infant against the floor it crawled on.