Developmental toxicity potential of paclobutrazol in the rat.

Paclobutrazol is used as a fungicide and as a plant growth regulator, but there are few studies about its potential toxic effects. Experiments were conducted to determine whether this compound has adverse effects on the reproduction and development of offspring. The influence of 1.0 mg/kg paclobutrazol (10 x the acceptable daily intake-ADI), by oral exposure during gestational organogenesis of rats, was evaluated on maturational and behavioural aspects of offspring development. This dose did not promote evidence of maternal toxicity and the weight of gravid uterus, fetus, and ovary on days 16 and 20 of pregnancy were not affected. Also, the pesticide did not affect body weight gain of the dams and offspring. However, the pups' survival at weaning was impaired by paclobutrazol. Beyond that, study of the functional state of rat pups' nervous system at different stages of postnatal development revealed some differences in treated ones. Damage was observed in the expression of acoustic startle reflex and altered locomotion and/or rearing in an open-field apparatus in treated pups depending on their age. There were no observed alterations in swimming behaviour. The data support further studies of the potentially toxic effects that exposing mothers to this pesticide may have on their litters.