Characteristics of pesticide pyrotechnic smoke devices.

Pesticide smoke generating products are widely used by amateurs and professionals but there is little published information available about their burn and deposition characteristics to enable the risks associated with using these devices to be assessed. This paper investigates their burn characteristics, deposition patterns, pesticide air concentrations and potential exposure to operators. Thirteen firings were carried out in different spaces with different ventilation conditions. Three types of devices were investigated: dicloran, permethrin and red dye. Pesticide air concentrations increased after firing, reaching a maximum determined by the room volume in approximately 10 min and decreasing exponentially as a result of ventilation and deposition. Ejected pesticide was present in the aerosol phase but there were only occasional traces of vapour. Settlement of pesticide was affected by surface orientation, height, sampling material and the pesticide-to-space volume ratio. The manufacturer's recommended treatment period for dicloran of 4 h followed by half an hour of ventilation may be insufficient to reduce pesticide to safe levels for re-entry under very calm conditions.

Dermal exposure of amateur or non-occupational users to wood-preservative fluids applied by brushing outdoors.

The results of an experiment to determine the likely dermal exposure of amateur or occasional users to wood-preservative fluids, applied by brushing onto a wooden fence outdoors are presented. Exposure was measured using FIVES, a fluorescence monitoring technique developed at the Health and Safety Laboratory. Dermal exposure could be examined and measured in a detail that would have been impossible using any other technique. A number of factors were found to affect dermal exposure, including some that were unexpected. Trousers, a long-sleeved shirt and permeable gloves offered 20 times the protection of shorts and a T-shirt. Differences between individual subjects' behaviour gave rise to variations of a factor of 10. There was far more contamination at lower ambient temperatures, possibly because of more vigorous brushing. Spirit-based fluid caused more exposure than water-based fluid, probably because the spirit flicked easily from the brush as a spray whereas the water remained in soapy globules. Only 1.6 times more fluid was applied in 1 h than in 0.5 h, but it caused 3.7 times as much contamination.

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.

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 tracer to quantify dermal deposition of chemicals such as pesticides. The subject stands inside a dodecahedral arrangement of ultraviolet (u.v.) strip-lights, which cause a given area of dye to fluoresce with a consistent 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 foreshortening of surfaces angled to the camera or to the inverse square law for surfaces further from the camera. Measurements on planar surfaces prove that the algorithm performs well in a large central region inside the dodecahedral lighting field. Field trials of the system show that although the free-standing apparatus is large and rather unwieldy, when fastened inside a box van it is practicable, portable and self-contained. It is suitable for measuring exposure arising from spraying operations and can be used, but with more limited success, in studies of dipping operations.