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Psoriasis is a chronic relapsing disease characterized by variable clinical features. Several factors may exacerbate its manifestations, or even trigger the disease, such as traumatic injury to the skin, physical and psychological stress, cold weather, excessive alcohol intake, and drugs such as lithium and Beta-blockers. We describe the most common features of psoriasis and the exogenous factors that may induce, trigger or exacerbate the disease.

Two experiments were conducted. In the first, 9 adult male subjects applied a marketed hair dye containing 2% lead acetate according to prescribed directions daily for a period of 90 days. Scalp, axillary and pubic hair were monitored for lead content before and at the end of the test period. Scalp hair analyses were used to confirm application of the hair dye; axillary and pubic hair were analyzed as biologic indicators of systemic lead absorption, i.e., metabolic incorporation of lead in hair growing at sites different from the dyed site. The axillary and pubic hair lead levels ranged from less than 6 to 41 ppm at the start and rose to 27 to 466 ppm at the conclusion of the experiment. Using 80 ppm hair lead as a measure of significant systemic absorption, 7 of 9 subjects showed this effect according to uptake by axillary hair and 4 of 9 according to pubic hair uptake. In the second experiment, blood and hair lead levels and blood erythroporphyrin were measured in 11 children from a pica clinic. Blood lead and hair lead levels were significantly correlated, i.e., r = +0.84. A regression formula was constructed relating these two parameters and blood lead values were predicted for the data of experiment 1, using observed hair lead values. The technique has important limitations; nevertheless, within these limitations, 1 of 9 subjects might be expected to have sustained an elevated blood lead level, i.e., in excess of 50 microgram/100 ml. It therefore appears that in the use of lead acetate hair dyes, some lead is absorbed systemically from the scalp.