THE RELATIVE SENSITIVITY OF 2 ARM-WASH TEST METHODS FOR EVALUATING THE MILDNESS OF PERSONAL WASHING PRODUCTS

The utility of controlled arm wash tests for evaluating the potential of personal washing products to induce skin irritation and dryness is well documented. This investigation directly compares the ability of t wo different arm wash protocols to discriminate between the relative m ildness of personal washing products. Both methods consist of a total of 18 treatments (four per day for four days, with two treatments on t he fifth day). Treatment using arm wash test Method 1 consists of a co ntinuous gentle washing for two minutes followed by rinsing. Treatment using Method II consists of a ten-second produce application and nine ty seconds exposure to the lather followed by rinsing. Method I, a mor e aggressive wash regimen, induced greater absolute levels of erythema and dryness, and also provided greater discrimination between product s of similar irritation potential. Method I and Method II appeared to exhibit a similar capability to discriminate between products based on differences in skin drying potential. Non-invasive instrumental measu rements of skin condition and function were consistent with clinical o bservations. The superior sensitivity of Method I will be especially v aluable when comparing mild cleansing produces. In contrast, Method II exhibited reduced capability to distinguish between cleansing product s and therefore has reduced potential to detect differences, especiall y with regard to irritation potential.