A guinea pig sensitization study was conducted to determine the dermal sensitization potential of DOW CORNING(REG.) 2-0707 Intermediate. This study was performed according to the OECD Guidelines No. 406 (July, 1992) and U.S. EPA Good Laboratory Practice Standards Part 792 (TSCA), 40 CFR 792, Final Rule, August, 1989. The test material was administered by intradermal (i.d.) injection of the dosing formulation (5% w/v) in DOW CORNING(reg.) 360 Medical Fluid to the shaved shoulder region of 20 male guinea pigs. Another group of 10 male vehicle control guinea pigs was handled in a similar manner, but was treated (i.d.) with DOW CORNING 360 Medical Fluid only. A third group of 10 male guinea pigs was treated with dinitrochlorobenzene (DNCB) in propylene glycol and served as a positive control. One week following i.d. injection of the first induction dose, a second induction dose of undiluted (100%) test material was applied topically to the test group animals for 48 hours. Animals in the vehicle control and positive control groups were dosed topically with DOW CORNING 360 Medical Fluid and DNCB, respectively. Three weeks following the first induction dose, test and vehicle control guinea pigs received a topical challenge dose (50% w/v) of test material/ DOW CORNING(reg.) 360 Medical Fluid formulation for 24 hours. Positive control guinea pigs were dosed similarly with 0.1% DNCB in propylene glycol. A second challenge was performed one week later in order to confirm the results ofthe first challenge. Tne skin response of all guinea pigs was evaluated at approximately 24 and 48 hours following completion of the challenge dose. The results were expressed in terms of the incidence and severity of the skin response. All of positive control animals exhibited a positive reaction at the DNCB challenge control site with a severity index of 3.40. No skin sensitization response was observed in the vehicle control animals. A positive response in the test substance-treated animals resulted in incidence and severity of 55% and 1.10, respectively, at the forty-eight hour scoring interval following the second challenge dose.