Accuracy and reproducibility of calibrations on the skin using the fives fluorescence monitor.

Dermal contamination from products such as pesticide formulations may be measured by adding a fluorescent dye as a tracer, and photographing the glow of the dye on the skin under ultraviolet light. The Fluorescence Interactive Video Exposure System (FIVES) fluorescence monitor, developed at the Health and Safety Laboratory, uses calibrations of intensity of glow against surface concentration of dye which are affected by the natural fluorescence of the skin and by skin hue. Calibrations of two dye/product mixtures upon the skin of several volunteers showed that a simple multiplicative correction procedure aligned all the responses to one calibration curve for each mixture. The palms of the hands were an exception, because their natural fluorescence was much higher than other areas of skin, and the relation no longer held. A further correction factor aligned their responses with the rest. The calibration data were fitted best by log-log polynomials, although linear polynomials were acceptable. Using this new procedure, the FIVES monitor could estimate dermal contamination to within +/- 70% of known applied doses. Upon exposure to light, the dyes on the skin were found to fade by 20% in 1/2 h, but no further in 1 h. The procedure and calibrations developed here were used in an experiment to estimate the likely dermal exposures of amateur or occasional biocide users, painting ready-to-use wood preservative fluids onto a trellis fence outdoors.