Responsiveness of 6 to 14 generations of birds to dietary dieldrin toxicity

The lethal dietary toxicity of dieldrin was estimated repeatedly during 8 years of testing young bobwhites ( Colinus virginianus ), Japanese quail ( Coturnix c. japonica ), ring-necked pheasants ( Phasianus colchicus ), and mallards ( Anas platyrhynchos ). Toxicities, quantified as 8-day LC50 values (5 days on toxic diet, followed by 3 days of untreated feed), were estimated at least 18 times per species. Average dietary LC50 values (ppm) and their 95% confidence limits for 14-day-old quail and 10-day-old pheasants and mallards were: bobwhite, 38 (34–42); Japanese quail, 61 (58–64); ring-necked pheasant, 56 (53–59); and mallard, 179 (163–195). No time-related changes were detected in LC50 values for any of the species.