Effect of patch type on the cumulative irritation potential of 4 test materials

Background Many different patch systems are available for predicting contact dermatitis. It is important to determine the ideal patch to meet the objective of the testing method. Objective The 21-day cumulative irritation test is well accepted for predicting irritation after repeated exposures. The patch type must allow separation of materials to predict irritation potential in the marketplace. Three patch systems were compared to determine which best provides this separation and prediction. Methods Four test materials were evaluated using 3 patch systems in a 21-day cumulative irritation test. Tested were water, 0.06% sodium lauryl sulfate (SLS), and 2 underarm products (UAP), one having lower and one having higher irritation potential. The patch types were; Webril pad and 8-mm and 12-mm Finn Chambers. Results Both the 12-mm Finn Chamber and Webril pad showed the ability to differentiate the higher irritating UAP and the 0.06% SLS from the lower irritation UAP product and water. The 8-mm Finn chamber was less discriminating, showing the 0.06% SLS to be the same as water and the lower-irritating UAP. Conclusion The Webril pad and the 12-mm Finn Chamber are better at discriminating irritation potential than is the 8-mm Finn Chamber. The 12-mm Finn Chamber might also allow discrimination with a lower degree of irritation.