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Microplastic release from the degradation of polypropylene feeding bottles during infant formula preparation


Polypropylene-based products are commonly used for food preparation and storage, but their capacity to release microplastics is poorly understood. We investigated the potential exposure of infants to microplastics from consuming formula prepared in polypropylene (PP) infant feeding bottles (IFBs). Here, we show that PP IFBs release microplastics with values as high as 16,200,000 particles per litre. Scenario studies showed that PP IFB sterilization and exposure to high-temperature water significantly increase microplastic release. A 21-d test of PP IFBs showed periodic fluctuations in microplastic release. To estimate the potential global exposure to infants up to 12 months old, we surveyed 48 regions, finding values ranging from 14,600–4,550,000 particles per capita per day, depending on the region. We demonstrate that infant exposure to microplastics is higher than was previously recognized due to the prevalence of PP-based products used in formula preparation and highlight an urgent need to assess whether exposure to microplastics at these levels poses a risk to infant health.

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Fig. 1: World market share of PP IFBs.
Fig. 2: IFB sample preparation and establishment and validation of the MP analysis protocol.
Fig. 3: MPs released from PP IFBs.
Fig. 4: Impact of temperature and repeated use on MPs released from three PP IFB products (not including accessories).
Fig. 5: Daily exposure of infants to MP worldwide.

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Data availability

All data analysed in this study are contained within the Supplementary Information. The raw data that support the findings of this study are available from the corresponding author upon request to J.J.W. or from the Figshare repository at Source data are provided with this paper.

Code availability

The mathematical algorithm used for MP exposure assessment has been included in the Methods. The sales data mining software Jungle Scout is available at


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This work was supported by Enterprise Ireland (grant number CF20180870), Science Foundation Ireland (grants numbers 12/RC/2278, 16/IA/4462 and 16/RC/3889), the School of Engineering Scholarship at Trinity College Dublin, and the China Scholarship Council (201506210089 and 201608300005). We also thank Keyence for help. The presentation of the material in this publication does not imply the expression of any opinion whatsoever on the part of Trinity College Dublin about specific companies or of certain manufacturers’ products and does not imply that they are endorsed, recommended, criticised or otherwise by Trinity College Dublin in preference to others of a similar nature. Errors and omissions excepted. All reasonable precautions have been taken to verify the information contained in this publication. However, the published material is being distributed without warranty of any kind, either expressed or implied. The responsibility for the interpretation and use of the material lies with the reader. In no event shall Trinity College Dublin be liable for damages arising from its use.

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Authors and Affiliations



J.J.W. and L.X. supervised the project and led the overall effort. D.L., J.J.W., J.J.B. and L.X. wrote the manuscript. J.J.B. contributed to the experimental design and validation. Y.S. and D.L. performed online data mining and analysing. D.L., Y.S. and L.Y. carried out the sample preparation. D.L. and J.J.W. carried out the Raman measurements. D.L., D.K.K. and J.J.W. carried out the AFM and scanning electron microscopy characterization. All authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Liwen Xiao, John J. Boland or Jing Jing Wang.

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Supplementary Information

Supplementary Figs. 1–8, Tables 1–8, Notes 1–8 and references.

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Source Data Fig. 1

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Numerical data and unprocessed source images used to generate Fig. 2

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Numerical data s used to generate Fig. 5

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Li, D., Shi, Y., Yang, L. et al. Microplastic release from the degradation of polypropylene feeding bottles during infant formula preparation. Nat Food 1, 746–754 (2020).

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