Development and Evaluation of a Quantitative Video-fluorescence Imaging System and Fluorescent Tracer for Measuring Transfer of Pesticide Residues from Surfaces to Hands with Repeated Contacts

A video imaging system and the associated quantification methods have been developed for measurement of the transfer of a fluorescent tracer from surfaces to hands. The highly fluor-escent compound riboflavin (vitamin B2), which is also water soluble and non-toxic, was chosen as the tracer compound to simulate the transfer from surfaces to hands of pesticide residues deposited on carpeted and laminate surfaces of a residence. The systemwas designed around the unique properties of riboflavin. Excitation energy was centered near 440 nm (in the blue region of the visible spectrum); emitted energy wasmeasured at 600 nm (in the red/orange region), well beyond the significant fluorescence peakmaximum of natural skin. A video camera system with an image intensifier was interfaced to an image processing analysis software system. Quanti-fication utilized chemometric techniques to account for the non-linearity of pixel detectivity and non-linear excitation strength. Method quantification and detection limits were approximately 0.1 and 0.02 mg/cm2, respectively. The relative error was100 % at the quantification limit, but <20 % at higher levels. Transfer of riboflavin to hands, resulting in dermal loadings in the range 0.1–2.0 mg/cm2, were measured with this system from surfaces whose loadings approximated the pesticide levels that occur in homes after broadcast application