In 2022, a team led by Marja H. Lamoree of the Free University of Amsterdam published some disturbing results.

Using a new analytical method on blood samples from 22 volunteers, they found that 77% had plastic particles. A year later, they also found plastic particles in the milk of three out of four mothers who participated in another study on the presence of these substances. Plastic can cause inflammation, or attenuate the immune response, so that bacteria such as Staphylococcus aureus cause more virulent infections.