EXPERT REACTION: Babies exposed to huge amounts of microplastics from their bottles

This paper highlights the need to increase research into understanding the role of plastic exposure in early life and is yet another report that plastic exposure is very widespread among developing infants. In humans, polypropylene is the most commonly used plastic in food preparation. Although infant baby bottles were studied in this paper, the list of potential sources of ingestion is large and relevant beyond polypropylene infant feeding bottles alone. The relevance of microplastics being released by heat and potentially ingested extends to other items, such as breast milk pumps, reheating milk in microwave containers, electric kettles and further sources.

The paper assessed the microplastic particle release into water from polypropylene infant feeding bottles when formula milk was prepared to standard instructions and bottles were sterilised. 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. The majority of microplastic particles were smaller than 20μm when detected in the liquid. Even smaller particles are likely to be present - so called nanoparticles - but the system did not capture particles less than 0.8μm.

Until recently, microplastics have not been able to be measured well but technological advances now allow this. A current research program is investigating early life plastic exposure and potential offspring neurodevelopmental harm at the Florey Institute of Neuroscience and Mental Health. We are predominantly studying the effect of larger plastic additives such as phthalates and bisphenols, and working actively with Australian organisations, such as the Queensland Alliance for Environmental Health Sciences, to expand the program to microplastics and nanoplastics.

We know plastic chemicals are very common and multiple sources contribute to the load in the human body. For example, in a Victorian birth cohort, we found >98% of the Australian women involved in the study had phthalate chemicals detectable in urine at 36 weeks gestation, and higher phthalate levels were associated with ingested, inhaled and adsorbed through skin sources (Ref: “Predictors with regard to ingestion, inhalation and dermal absorption of estimated phthalate daily intakes in pregnant women: The Barwon infant study”. Environment International. 2020; 139:105700)

There is great need to better understand the potential adverse health consequence of early life exposure to man-made chemicals - not only microplastics but other plastic chemicals and nanoplastics too.

The findings of this paper may sound quite scary, at first, but we should keep in mind the research only looks at potential microplastic exposure, it does not look at potential effects of such exposure. Indeed, we really know very little about the effects of microplastics on children - or adults for that matter. The particles in the study are listed as being around 1-3 micrometres in size (for comparison, a printed full stop in a newspaper is ~300 μm across); it is quite possible they just pass out of the body very quickly.

We also need to keep in mind that the final numbers in this paper are not measurements but estimates from a model - and any mathematical model is only as good as the data you put into it. In this case there is a fair degree of uncertainty since the authors estimate how many bottles were in use in different countries by scraping sales data from the internet - mostly Amazon. They also assume each bottle shed microparticles the same way as in the lab tests, which they may not. This means the numbers listed in the paper should be treated as indications, not absolutes. We certainly should not be making parents feel bad for using plastic bottles.

The above non-withstanding, this study is another piece of the puzzle that illustrates that microplastics problem is likely much bigger than we think. This issue is something we need to start really getting to grips with sooner rather than later.

The findings were examined in a global context by estimating infant daily formula intake and breastfeeding rates to assess the scope of microplastic burden due to polypropylene bottles in infants up to 12 months old.

Findings from this study align with our recently published data that humans could potentially ingest up to 5mg per week (Senathirajah et al.,2020), yet it could be an underestimation. Fine microplastics (<1mm size) are so invisible; we may not even notice that they are in our diet.

As shown in recently published data, teabags can release billions of microparticles at brewing temperature, and another study found 4–29 million microparticles per litre were removed from electric plastic kettles. Taken together, evidence of human ingestion of microplastics are mounting.

However, evidence for the toxicity of micro and nanoplastics in human food sources is scarce. There are several methodological challenges in this study, that are not answered and can't be interpreted properly. These findings should be interpreted within a toxicological context, estimation of the mass in addition to the number will be the first step towards human health risk assessment.

This is shocking new research that further adds to our growing understanding of the prevalence of microplastics in our world. The research targets the release of microplastics from baby formula bottles and shows that these bottles are contributing large amounts of plastic to infant formula and diet. Infants are the most susceptible to the impacts of chemical exposure and contaminants. The small body size of an infant means that they can receive a proportionately larger dose of plastic-derived chemicals as these microplastics break-down in the digestive tract. There is a wealth of research that supports the absorption of chemicals in humans (and animals) from ingestion of microplastic fragments. 
 
One additional concern in the way chemicals in plastic become liberated when heated. Infant bottles are commonly heated prior to feeding. The addition of heat may make these chemicals more bio-accessible, potentially leading to yet a further increase in chemical absorption in the body. 
 
The research suggests that infants fed using a bottle may be exposed to unacceptably high concentrations of microplastics. Exposure to chemicals in the environment or in food at this age group may have significant health implications in later life, including learning difficulties, development of certain disease and development of cancers, among others. There is also a growing body of evidence for inter-generational impacts on offspring from many of the chemicals commonly found in plastics. 
 
It concerns me that there is almost no regulation of how infant formula bottles are manufactured, or standards that must be met particularly for bottles available online. There is clearly a need for this to be further investigated and regulations to implemented.