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 fluorescent 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 system was designed around the unique properties of riboflavin. Excitation energy was centered near 440 nm (in the blue region of the visible spectrum); emitted energy was measured at 600 nm (in the red/orange region), well beyond the significant fluorescence peak maximum of natural skin. A video camera system with an image intensifier was interfaced to an image processing analysis software system. Quantification 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 micro g/cm(2), respectively. The relative error was approximately 100% 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 micro g/cm(2), were measured with this system from surfaces whose loadings approximated the pesticide levels that occur in homes after broadcast application.