On November 25, 2019, the European Union (EU) Observatory for Nanomaterials (EUON) announced the publication of a study published in Frontiers in Pharmacology entitled “Unpredictable Nanoparticle Retention in Commonly Used Plastic Syringes Introduces Dosage Uncertainties That May Compromise the Accuracy of Nanomedicine and Nanotoxicology Studies.”  The researchers in the study radiolabeled a variety of different nanoparticles, loaded suspensions of particles into different plastic syringes, and then measured the radioactivity left behind after emptying the nanoparticle suspension from the syringe.  This provided a simple way to measure the fraction of nanoparticles that remained stuck inside the syringe.  According to EUON, in the worst case, up to 79.1 percent of the nanoparticles remained.  The study found variability in the amounts remaining behind depending on the types of particles and syringes used.  The researchers propose checks to determine the correct combination of syringe and nanoparticle that should be used to minimize the problem.  The study did not identify the root causes of the high variability between the different nanoparticles and syringe types used.