Researcher(s)
- Lindsey Smathers, Nutritional Science, University of Delaware
- Ally Schoneman, Nutritional Science, University of Delaware
Faculty Mentor(s)
- Melissa Melough, Department of Health Behavior and Nutrition Sciences, University of Delaware
Abstract
Microplastics are ubiquitous in the environment and have been detected in numerous human tissues, along with breastmilk. Data on the microplastic contents of breastmilk are sparse, and existing reports exhibit substantial variability, potentially due to differences in methodology. To assess infants’ exposure to microplastics through feeding and evaluate related health risks, reliable methods for the extraction and detection of microplastics are essential. The objective of this study was to compare the performance of two protocols for digestion of breastmilk, enabling microplastics extraction: 1) a chemical digestion (treated with 10% potassium hydroxide) previously described in the literature by Ragusa et al., and 2) a newly developed enzymatic digestion (treated with amylase, sodium citrate, lipase, trypsin, hydrogen peroxide, and sodium dodecyl sulfate). Protocol performance was evaluated by assessing microplastic recovery and impacts on microplastic morphology. To assess recovery, samples were spiked with 0.010g (± 0.002g) of polyamide (nylon 12) particles (10-50μm) prior to digestion. The weight of retained particles was measured after digested samples were vacuum filtered through a cellulose ester membrane with pore sizes of 20-25μm. To assess potential impacts on morphology, microplastics were examined using a scanning electron microscope before and after digestion. Spiked breastmilk samples treated with the chemical protocol appeared incompletely digested and failed to pass through the filter. Samples treated with the enzymatic protocol were successfully filtered, and approximately 97.1% of spiked microplastics were recovered. Microplastics extracted using the enzymatic protocol appeared identical in shape, size, and surface characteristics compared with undigested microplastics. In conclusion, while the chemical digestion could not be replicated, the enzymatic digestion resulted in excellent recovery and preserved the morphology of the microplastics. Future studies should evaluate the enzymatic protocol using smaller pore-size filters to improve recovery of smaller microplastics, and validate recovery across additional polymer types.