Critical developmental effects on rat fetuses of low-level arsenic exposure in water

Abstract

Arsenic has been incriminated to cross the placental barrier both in humans as well as animals, which might be the putative cause of alteration(s) in developmental defects reported in fetuses. The present study was conducted to determine the teratogenic effect of arsenic induced toxicity, when given at the same level (0.0191 to 0.2080 mg/l) at which it is found in drinking water in different parts of India. Young male and female Wistar rats were randomly divided in four groups viz. I, II, III, and IV and were given sodium arsenite at a dose rate of 0.01 mg/l, 2.5 mg/l, 5 mg/l and distilled water respectively. The animals were kept for a period of 10 weeks prior to mating and fed sodium arsenite at the doses described, and pregnant females were sacrificed on 20th day of gestation and fetuses were collected. Gross anomalies of the foetus were examined. Half of each litter was processed for skeletal examination using Alizarin Red S staining while the remaining foetus was fixed in Bouin’s solution for visceral tissue evaluation. There were increased foetal resorption(s) in all treated groups. The foetal body weights and crown to rump lengths were significantly decreased and the percent gross, visceral and skeletal anomalies were significantly increased in fetuses of dams of arsenic treated groups in a dose dependent manner. The wrist drop, subcutaneous hematoma, internal hydrocephalus, cerebellar hypoplasia, microphthalmia, dilated renal pelvis, roundening of heart, incomplete ossification of skull bones, vertebrae, ribs, and agenesis of phalanges and caudal vertebrae were the most important foetal malformations. The occurrence of foetal gross, skeletal and visceral malformations were more severe in the group III followed by group II, suggesting the teratogenic nature of arsenic (sodium arsenite). It was concluded in the present study that albeit when arsenic was fed at lower dose mimicking the levels in the field conditions, it significantly caused developmental anomalies in the present study discernible as gross, visceral and skeletal anomalies.