New insights into the release of microplastics from breastmilk storage bags

In a recent study published in Environmental Pollution, researchers from China analyzed the quantity, size, and composition of microplastics and other particle matter released into breastmilk from disposable breastmilk storage bags.

Background

Micro- and nano-plastic contamination is one of the most widespread and predominant types of plastic pollutants and poses serious health risks to all lifeforms. Studies have detected the presence of microplastics in human blood, various organs, the placenta, and feces. Experiments with mice have shown that microplastics in the gut can cause microbiome dysbiosis and disorders in lipid metabolism, while nano-plastic contaminants have been seen to cause behavioral disorders and brain damage by crossing the blood-brain barrier in fish.

Recent research indicates that infants exposed to even low doses of microplastics in the initial stages of development can suffer from disruptions in the exchange of gas and nutrients, causing long-term health problems. One study reported that baby bottles made of polypropylene could release plastic particles at concentrations of 1.62 × 10⁷ per liter, while other studies have reported the presence of microplastics in dairy milk, bottled water, food in take-out containers, and edible salt.

Disposable breastmilk storage bags, which can be used to store expressed breastmilk, have become very popular due to their convenience in feeding newborns. These can be used to store breastmilk for up to four hours at room temperature or four days under refrigeration. Given its popularity among mothers of newborns, it is essential to understand the characteristics of the microplastics released from these storage bags.

About the study

In the present study, the researchers selected six breastmilk storage bags commonly found in retail stores and online retailers. The labels indicated that these bags were made from different types of polyethylene, such as low-density polyethylene, linear low-density polyethylene, and polyethylene terephthalate.

To isolate the microplastics and other particle matter released into the breastmilk storage bags, the bags were filled with a sodium dodecyl sulfate (SDS) solution, sealed, and allowed to rest for 12 hours at room temperature. A platinum-coated polycarbonate membrane was then used to filter the microplastic and other particulate matter from the SDS solution.

An optical microscope was used to observe the morphology of the microplastics isolated from the samples. A combination of micro-Raman spectroscopy and confocal microscopy was used to determine the composition of the isolated microplastic and other particle debris. Additionally, energy dispersive spectroscopy and scanning electron microscopy were used to analyze the elemental composition and morphology of the isolated particles.

Results

The results reported that most of the particle debris released into the SDS solution from the breastmilk storage bags consisted of polyethylene, nylon-6, and polyethylene terephthalate particles. When three similar bags were examined, the weight of the released particles was found to be between 0.22 and 0.47 mg. Based on the average breastmilk intake by infants, which is 650–850 mL, 0.61 to 0.89 mg of microplastics were thought to be ingested by an infant per day if fed exclusively from breastmilk kept in storage bags.

Most of the particles were less than 300 µm in size with irregularly shaped floccules. These particles differed from those released from mineral water bottles, baby milk and feeding bottles, and take-out containers. Smaller particles in the range of 1–20 µm floating near the top of the sample solution were similar to the microplastics found in nursing bottles. The larger particles between 50 µm and 300 µm were found distributed throughout the solution.

Additionally, large quantities of oval, spherical, and irregularly shaped submicron-sized particles similar to the nano-plastics released from some plastic teabags were also found in the SDS solution. However, the energy dispersive spectroscopy and micro-Raman spectroscopy results did not indicate the presence of any non-plastic particles, such as minerals, either in the breastmilk storage bags or released into the SDS solution.

Conclusions

Overall, the results reported that if infants were fed exclusively on pumped breastmilk stored in breastmilk storage bags, on average, an infant would ingest 0.61 to 0.89 mg of microplastics a day. Increasing concentrations of polyethylene microplastics can disrupt the microbial balance in the gut and impact the synthesis of short-chain fatty acids, affecting the infant's growth. Microbiome dysbiosis can also result in an increased abundance of harmful bacteria in the gut.

Given the widespread use of plastics in food storage and feeding products such as baby bottles, teats, and breastmilk storage bags, infants' exposure to microplastics needs further investigation, and alternate materials for storage and handling of breastmilk and other food for infants need to be explored.

Written by

Dr. Chinta Sidharthan

Chinta Sidharthan is a writer based in Bangalore, India. Her academic background is in evolutionary biology and genetics, and she has extensive experience in scientific research, teaching, science writing, and herpetology. Chinta holds a Ph.D. in evolutionary biology from the Indian Institute of Science and is passionate about science education, writing, animals, wildlife, and conservation. For her doctoral research, she explored the origins and diversification of blindsnakes in India, as a part of which she did extensive fieldwork in the jungles of southern India. She has received the Canadian Governor General’s bronze medal and Bangalore University gold medal for academic excellence and published her research in high-impact journals.