Very high lethal dose, but "2240 mg/kg" is exactly what the author reported. --> It's obviously a rounding error, the original source is "2.24 mg/kg (95% confidence limits 1.49–3.39 mg/kg)." Compare original source "Branch 1981. Venom yields from three species of side-biting snakes (Genus Atractaspis, Colubridae). Toxicon 19:271-277)"

