The remaining concentrations of linear alkylbenzene sulfonate sodium salt (LAS) in the clothes and its irritation in atopic dermatitis

We studied the irritation of linear alkylbenzene sulfonate sodium salt (LAS) in the laundry detergents on the skin of atopic dermatitis (AD). LAS is one of the main surfactant in laundry detergents. First, we measured the remaining concentration of LAS in the clothes after laundry. The subjects were 10 patients of atopic dermatitis. The amounts of LAS in the new T shirts after washed 5 times by their own usual way were ranged from 48ppm to 1300ppm. Secondly, we patch tested the other 20 AD patients with 6 different concentrations of LAS, 2 concentrations of a popular Japanese commercial laundry detergent, and one T shirt after washed five times. Only one out of the 20 cases showed a faint macular erythema with 1000ppm of the LAS solution. Our results suggested that the remaining LAS in the clothes may not cause a significant irritation.