.png){kind=icon}
OECD 425/OCSPP 870.1100: Acute oral toxicity (up-and-down)
In 1985, Bruce proposed to use an up-and-down procedure (UDP) for the determination of acute toxicity of chemicals. The method permits estimation of an LD50 with a confidence interval. The results allow a substance to be classified for acute toxicity according to the Globally Harmonised System of classification and labelling of chemicals. This test is intended for use with rodents.
The OECD 425 guideline describes a limit test and a main test. Rodents are dosed one at a time and observed for a minimum of 48-hours before deciding on whether and how much to dose the next animal. The first rodent is dosed a step below the best preliminary estimates of the LD50. The second rodent receives a lower dose, based on results for the first rodent. The LD50 is calculated using the maximum likelihood method.
The results of the main test procedure serve as the starting point for a computational procedure to provide a confidence interval estimate where feasible.
