The study was designed to determine the toxicity of graded concentrations of TMAH when applied repeatedly to the shaved dorsal skin. A vehicle control group of equal size was exposed dermally to the vehicle (distilled water) only. Initially, the study was composed of 5 groups consisted of 10 rats/sex/group. However, as described in detail below, the groups of male and female rats were dosed with different graded concentrations of the test substance ultimately resulting in a total of 7 treatment groups between both sexes. The dosing was staggered over two days, with each sex (males and females) being initiated over two consecutive days. The vehicle and test substance formulation was applied to the reservoir of a Hill Top Chamber(trademark) (Hill Top Biolabs, Inc., Cincinnati, Ohio) which was then placed on the shaved animal's back behind the shoulder blades. The chamber was held secure with an elastic cloth band fastened with Velcro(trademark). The chamber and wrapping were removed 6 hours after dosing. To prevent potential ingestion of the test substance formulation, each animal was fitted with a plastic neck collar (Ejay International Inc., Glendora, CA) on days of treatment (i.e., collar removed on Saturday morning and replaced on Monday prior to dosing). The rats were weighed prior to treatment initiation (Day 0) of the study and weekly thereafter. Dosing volumes were based on the most current body weight. Food consumption was monitored to coincide with body weights. Rats were observed daily for overt signs of toxicity. At least once per week rats were given a thorough hand-held clinical examination which included evaluation of the application site skin.