Patch test responses to rockwool of different diameters evaluated by cutaneous blood flow measurement

Rockwool is a man-made mineral fiber used mainly for insulation, which can cause mechanical skin irritation. This study was performed to evaluate the irritant potential of rockwools of different diameters and to compare the change of blood flow, measured by laser Doppler flowmetry, at different patch test occlusion times with rockwools. Rockwool A (mean diameter 4.20 +/- 1.96 mu) was more irritating than rockwool B (mean diameter 3.20 +/- 1.5 mu). The difference was more clearly observed in a 48-h patch test than in an 8-h or 24-h test. We concluded that laser Doppler blood flow measurement was a useful experimental tool for the evaluation of irritant patch test responses to mechanical irritants like rockwool, and that 48 h or more of occlusion time was necessary to produce irritant patch test responses to certain types of rockwool.