Test No. 418: Delayed Neurotoxicity of Organophosphorus Substances Following Acute Exposure

The test substance is administered orally in a single dose to domestic hens. The animals are observed for 21 days, then the remainder of the hens are killed and histopathological examination is undertaken.

The young adult domestic laying hen (Gallus gallus domesticus), aged 8 to 12 months, is recommended. The single dosing with the test substance should normally be by the oral route using gavage, gelatine capsules, or a comparable method. The treatment group should contain, at least 12 hens, and the positive control group at least 6 hens. The objective of the preliminary study is to maximize the main study dose. The limit test corresponds to one dose level of at least 2000 mg/kg body weight/day. The dose level of the main study should be high as possible taking into account the results of preliminary study and the maximum dose level (2000 mg/kg bw/d). The results of this study include measurements (weighing), biochemistry (neuropathy target esterase) and, at least, daily and detailed observations, as well as gross necropsy and histopathology. The findings of this study should be evaluated in terms of the incidence, severity, and correlation of behavioral, biochemical and histopathological effects and any other observed effects in the treated and control groups.

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