Simulated transfer of liquids and powders from hands and clothing to the mouth

A series of laboratory experiments was carried out to assess transfer of liquids (vinegar) and powders (calcium acetate and magnesium carbonate) from hands, arms, gloves, respirators, clothing, and pens to the oral cavity or the perioral area (the area surrounding the mouth). Experiments were carried out with four volunteers. The donor area (the hands, arms, gloves etc.) was loaded with a known mass of the test substance and was then brought to contact the receiver area (the oral cavity or the perioral area). The percentage of the substance on the donor that transferred to the receiver (the transfer efficiency or TE) was assessed using saliva samples and gauze wipes of the perioral area. Magnesium carbonate was measured on gauze and in saliva using inductively coupled plasma/atomic emission spectrometry. Calcium acetate and vinegar were measured using ion chromatography/electrochemical detection. Average transfer efficiencies were calculated for each substance and transfer scenario; these were compared using ANOVA and Kruskal-Wallis tests. Overall, direct transfer from the hands to the oral cavity was significantly higher (mean TE = 51.6) than indirect transfer from the hands to the oral cavity via the perioral area by licking the lips (mean TE = 11.5). The results suggested higher TEs for liquids than for solids and that hand-to-mouth TEs may increase with water solubility. Transfer from bare arms to the perioral area was higher than from arms covered by cotton sleeves for both liquids and powders. Although TE data are often required by models estimating exposure by inadvertent ingestion, relatively few published data are available. This study has provided evidence of some factors that may influence transfer of chemicals from hands or objects to the mouth (physical form, use of clothing, etc.) and has provided data that is essential for the development of predictive exposure models of inadvertent ingestion exposure.