CUMULATIVE IRRITANCY IN MAN TO SODIUM LAURYL SULFATE - THE OVERLAP PHENOMENON

Repeated contact of skin with surfactants causes irritation often characterized by dryness, erythema and scaliness. Morphologically healed skin after preexposure can still evoke a stronger reaction to any subsequent exposure of an irritant. Cumulative irritancy using the overlap phenomenon was studied. The effects of repeated and prolonged application of sodium lauryl sulfate (SLS) on human skin in vivo (healthy adult volunteers) were evaluated using non-invasive techniques of TEWL and skin capacitance measurements and visual scoring. The inability of TEWL and skin capacitance to achieve pretreatment values 2 weeks post SLS treatment suggests the possible detrimental effects of SLS on skin lipids. The surfactant effect was cumulative and dehydrating effects on prolonged and repeated application were observed.