Examination of Japanese quail chicks in one-generation feeding studies for effects of the agrochemicals dimethoate, fentin hydroxide, and vinclozolin on skeletal development

An established method for evaluation of skeletal anomalies was successfully adapted to Japanese quail (Coturnix coturnix japonica) and performed on 793 untreated 1-day old chicks to develop an historical control database. Incomplete ossification of the pelvic bones and irregular position of the toes were rather frequently observed. Subsequently, 702 chicks from the treatment groups in three one-generation reproduction studies with the pesticides dimethoate, triphenyltin (fentin) hydroxide, and vinclozolin were compared to their respective controls and the whole historical database. Presumed treatment-related effects were confined to a higher number of chicks with incomplete ossification of vertebrae and pelvis when the hens had been administered fentin hydroxide at a dietary level of 30 ppm for up to 6 weeks, corresponding to a mean daily substance intake of 3.1-3.9 mg kg(-1) body weight (bw). Thus, inclusion of teratological findings as a further endpoint confirmed the previously established NOAEL of 3 ppm (equal to 0.28-0.35 mg kg(-1) bw/day) based on reproductive effects in this study. No effects on skeletal development were seen with dimethoate and vinclozolin up to the highest dietary concentrations of 70 and 500 ppm, corresponding to estimated mean daily intakes of about 8 or 56 mg kg(-1) bw. The suitability of the method for reliable detection of skeletal anomalies was proven. The established method can be considered useful in providing additional information for ecotoxicological risk assessment.