Background: Melanosis and leucomelanosis with or without keratosis are the earliest symptoms of arsenicosis. Uneven distribution of arsenical melanosis and leucomelanosis in skin led us to investigate the possibility of preferential secretion of arsenic and three constituents of sweat; cholesterol, vitamin E, and zinc.
Methods: Twenty-four-hour skin secretion was collected from skin lesions and unaffected sites of 20 patients. Skin secretions were collected from 20 people exposed to arsenic-contaminated drinking water and 20 healthy, unexposed individuals.
Results: The secretion of arsenic from the skin of healthy controls (mean ± SE; unit: μg/in.(2) of skin/24 h; chest: 0.6 ± 0.2; back: 0.3 ± 0.1; abdomen: 0.5 ± 0.2) was increased several folds in arsenic-exposed controls (chest: 8.4 ± 1.8; back: 8.3 ± 1.9; abdomen: 6.7 ± 1.8) and patients (chest: 9.2 ± 1.3; back: 7.8 ± 1.3; abdomen: 5.2 ± 1.0). There was no difference in the skin lesions and unaffected sites in patients. However, the secretion of cholesterol was significantly lower in the chest of patients (190 ± 36) and healthy controls (686 ± 100) (p < 0.001). Secretions of vitamin E were low in healthy controls (chest: 8.5 ± 3.1; back: 5.2 ± 1.7; and abdomen: 8.7 ± 2.4), higher in arsenic-exposed controls (chest: 30.2 ± 8.1; back: 16.3 ± 8.9; and abdomen: 24.8 ± 9.3), and highest in patients [chest: 91.4 ± 14.9 (p < 0.0001 vs. control); back: 72.4 ± 13.2 (p < 0.001 vs. control); and abdomen: 46.8 ± 12.9]. Chronic intake of arsenic led to several folds higher secretion of zinc both in patients and in arsenic-exposed controls. One molecule of arsenic appears to be co-secreted with two molecules of zinc.
Conclusion: Arsenic skin lesions showed no alteration in secretion of arsenic, although the secretion of cholesterol, vitamin E, and zinc was changed. Potential implications are discussed.