The lower temperatures and relative humidity manifest during the late autumn and wintertime studies were verified by consulting historical weather charts (http://www.srh.noaa.gov) for the specific locale where the testing took place.
Even with seasonal effects noted, it was possible to categorize the irritation potential of different formulations across studies. Based on the comparative TR50 values across all 24 formulations, the general ranking of irritation potential was (by decreasing irritancy): mold/ mildew removers (average TR50 = 0.37 h) > disinfectants/sanitizers (0.64 h) > fabric softener concentrate (1.09 h) = aluminum wash (1.20 h) > 20% SDS (1.81 h) > liquid laundry detergents (3.48 h) > liquid dish deter- gents (4.16 h) = liquid fabric softeners (4.56 h) = liquid hand soaps (4.58 h) = shampoos (5.40 h) = hard surface cleaners (6.34 h) > powder automatic dish detergents (>16 h) = powder laundry detergents (>16 h). Note that, given the precision of the curve fitting method, all formulations with average TR50 values between 4 and 7 h were essentially equivalent. The powdered formulations (average TR50 values > 16 h) produced few or no skin reactions. The consistent pattern of results obtained, by product class, for these 24 detergent formulations across 7 studies conducted over a 4 year period attest to the utility of this human test method as a suitable and ethical approach for screening the acute irritation potential of these product types. Although conducted on generic prototype formulations, the test results are certainly relevant to marketed formulations within the distinct