U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Date of this Version



Human–Wildlife Interactions 8(1):123–129, Spring 2014.


U.S. government work.


Alpha-chloralose (AC) is used to capture nuisance waterfowl so that they can be relocated. Concerns for food safety limit its use prior to or during the waterfowl hunting season. To determine its half-life in tissue, we administered AC to adult male (n = 7) and female (n = 5) mallard ducks (Anas platyrhynchos) via oral gavage. A gel capsule containing 100 μCi of radioactive AC (14C-AC) and sufficient nonlabeled AC to produce a dose of approximately 30 mg/kg was given to each duck.The ducks were euthanized at 2, 6, 10, and 18 hours postdosing (n = 3 per exposure period), and tissue samples were collected for radioactive analysis. Residues observed in edible tissues from ducks dosed with radioactive AC demonstrated a delayed uptake as the duck was under the anesthetic effects of the AC. Following the period when the ducks were unconscious, most of the AC was rapidly excreted from the body with mean half-life (t½) values of 9.0 hours, 9.8 hours, and 9.1 hours for breast muscle, liver, and skin, respectively. An approximation of total excretion (99%) was made by taking 7 times the t½, resulting in values of between 27 to 33 hours post-exposure. These results suggest that tissues from mallard ducks are safe for human consumption 48 hours after dosing, a period that is significantly shorter than the FDA-required 30-day withdrawal period.

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