Fed with a side of microplastics: interventions to reduce plastic exposure via infant formula and human milk (FLES)

Babies are fed human milk or infant formula in their first year of life. Many will be fed expressed milk or formula that has been stored in plastic and is heated and served in a plastic baby bottle. This may result in exceptionally high exposures to small plastic particles, i.e. micro- and nanoplastics (MNPs).

Disconcertingly, there is a dearth of information on exposure to MNPs in infancy. Infants are generally more vulnerable to environmental hazards, and therefore, these potentially high exposures are cause for concern.


In this project, researchers will quantify the concentrations and characteristics of MNPs in human milk and infant formulas. We will also carry out interventions to compare levels of MNP contamination in human milk and infant formula prepared using typical versus alternative approaches. Alternative approaches may, for example, be glass baby bottles. This will provide novel evidence on MNP exposures in infants and ways parents and caregivers may reduce these exposures.


First, 50 breastfeeding women will be recruited. The women will donate two milk samples, using a protocol designed to minimize MNP contamination. They will also complete a questionnaire. The researchers will then conduct experiments with human milk and infant formula to assess the impact of storage, serving and preparation on MNP profiles. For example glass vs. plastic storage, the age of the plastic bottle and preparation techniques like automatic bottle warmers, a microwave, and water bath. The mass concentration of MNPs will be assessed by pyrolysis-gas chromatography mass-spectrometry (Py-GC/MS). Characteristics of MNPs will be assessed using spectro-microscopic techniques, including atomic force microscopy coupled with infrared spectroscopy (AFM-IR).

Intervention protocols will be refined based on input from stakeholders and results will inform the co-creation a guideline for reducing MNP contamination of expressed human milk and infant formula.

Collaboration partners

This project is carried out by dr. V.C. Lenters and colleagues from Vrije Universiteit Amsterdam, in collaboration with Amsterdam UMC, Emma Children Hospital and Utrecht University.

(Expected) results

This project will generate novel data on quantities and characteristics of MNPs in human milk and infant formula. With the results exposure estimates for MNPs in infancy for the Dutch population will be calculated. This data will enable exposure assessments and future health risk assessments for the sensitive window of early life.

Additionally, this project will generate data on the effectiveness of interventions to reduce MNP contamination during storage, preparation and feeding of expressed milk and infant formula. Finally, this project will create and widely disseminate a practical guideline for reducing MNP exposures via bottle feeding.


Project number:
Duration: 43%
Duration: 43 %
Part of programme:
Project lead and secretary:
dr. V.C. Lenters PhD
Responsible organisation:
Vrije Universiteit Amsterdam