This letter is to inform you of the results of a recently conducted acute oral toxicity study (LD50) in rats with a R&D proprietary mixture containing these materials. Groups of 5 male and 5 female Crl:CD*BR rats were fasted overnight and then administered the test mixture by intragastric intubation. After dosing, the rats were observed for mortality and clinical signs of toxicity over a 14-day observation period. The R&D proprietary mixture contained 2,4-D, Metsulfuron Methyl, and Chlorimuron EthyL The rats were dosed at 362, 521, or 750 mg/kg. Mortality occurred in 0/10, 6/10, and 9/10 rats dosed at 362, 521, and 750 mg/kg, respectively. Hypoactivity and ataxia were observed in surviving male and female rats at all dosages. The LD50 was calculated to be 527 mg/kg.