Migration of Soluble Polymers in Human Saliva during Swabbing Characterized by Direct Electrospray Ionization Mass Spectrometry

Medical swabs are commonly used in routine medical sampling and testing of human body fluids, such as saliva and sputum. Many medical swabs are made of plastic polymers. Exposure to plastic medical swabs containing many free soluble polymers and residual monomers could increase the potential health risk. Conventional analytical methods for assessing personal exposure to polymers usually require complex sample preparation and time-consuming analytical procedures. In this study, we established a direct electrospray ionization mass spectrometry method to investigate the occurrence and species of soluble polymers in different medical swabs. The migration of typical soluble polymers, i.e., PA6 and PEG, was found in medical swabs and human saliva after swabbing within seconds. The amounts of PA6 and PEG were found to be nanograms per swab. Trace polymer could rapidly reside in saliva within seconds (e.g., 3 s). The exposure level of polymer residual was evaluated during different swabbing times and saliva volumes, showing the concentration of soluble polymers in saliva at the ng/mL level. Despite the low concentration and low toxicity of soluble polymers in saliva, it is anticipated that this method could offer a convenient and simple way to evaluate polymer exposures rapidly. We also hope our findings will attract more attention to the health risks of ubiquitous plastic materials in daily life and propose an efficient strategy to eliminate saliva polymers.