How much poison is needed for a rat? - briefly
A single adult rat (~250 g) requires approximately 0.02–0.05 mg of a potent anticoagulant rodenticide such as «bromadiolone» to reach a lethal dose. This corresponds to roughly 0.1–0.2 mg per kilogram of body weight.
How much poison is needed for a rat? - in detail
Determining the lethal quantity of a toxicant for a laboratory rat requires reference to the median lethal dose (LD₅₀), expressed in milligrams of substance per kilogram of body weight. The LD₅₀ varies with the chemical class, the formulation, and the physiological condition of the animal.
Typical oral LD₅₀ values for commonly used rodenticides are:
- «warfarin» – 30 mg kg⁻¹ (average adult rat)
- «bromadiolone» – 0.3 mg kg⁻¹
- «zinc phosphide» – 150 mg kg⁻¹
- «diphacinone» – 10 mg kg⁻¹
- «strychnine» – 2 mg kg⁻¹
An average adult rat weighs approximately 250 g (0.25 kg). Multiplying the LD₅₀ by the animal’s mass yields the approximate amount required to cause death in 50 % of a test population:
- Warfarin: 30 mg kg⁻¹ × 0.25 kg ≈ 7.5 mg
- Bromadiolone: 0.3 mg kg⁻¹ × 0.25 kg ≈ 0.075 mg
- Zinc phosphide: 150 mg kg⁻¹ × 0.25 kg ≈ 37.5 mg
- Diphacinone: 10 mg kg⁻¹ × 0.25 kg ≈ 2.5 mg
- Strychnine: 2 mg kg⁻¹ × 0.25 kg ≈ 0.5 mg
Several variables modify these estimates. Younger or malnourished individuals exhibit lower tolerance; genetic resistance can increase required doses; the presence of food in the gastrointestinal tract may reduce absorption; and the route of administration (oral versus intraperitoneal) changes bioavailability. Formulations containing attractants or carriers may alter the effective dose delivered.
Regulatory and ethical frameworks impose strict limits on the use of lethal agents in research. Institutional animal care committees demand justification of any lethal experiment, preference for non‑lethal alternatives, and implementation of humane endpoints. Personal protective equipment and proper disposal procedures are mandatory to prevent accidental exposure.
In summary, the required amount of a rodenticide for a typical 250‑g rat ranges from a few tenths of a milligram for highly potent compounds such as strychnine to several tens of milligrams for less potent agents like zinc phosphide. Accurate dosing depends on precise knowledge of the chemical’s LD₅₀, the animal’s weight, and the influencing physiological and environmental factors.