A NOVEL LIGHTING SYSTEM FOR THE MEASUREMENT OF DERMAL EXPOSURE USING A FLUORESCENT DYE AND AN IMAGE-PROCESSOR

A video technique is described which uses a fluorescent dye as a trace r to quantify dermal deposition of chemicals such as pesticides. The s ubject stands inside a dodecahedral arrangement of ultraviolet (u.v.) strip-lights, which cause a given area of dye to fluoresce with a cons istent intensity over a range of spatial and angular positions within the lighting field. A special algorithm and an additional point source light enable local compensation factors to be calculated to allow for the reduction of apparent surface areas, due either to the foreshorte ning of surfaces angled to the camera or to the inverse square law for surfaces further from the camera. Measurements on planar surfaces pro ve that the algorithm performs well in a large central region inside t he dodecahedral lighting field. Field trials of the system show that a lthough the free-standing apparatus is large and rather unwieldy, when fastened inside a box van it is practicable, portable and self-contai ned. It is suitable for measuring exposure arising from spraying opera tions and can be used, but with more limited success, in studies of di pping operations.