Congenital malformations in rats exposed to tap water

Abstract

Previous research has demonstrated increased rates of neural tube defects, cleft palates and rib malformation in CD‐1 mice exposed to tap water from a variety of municipalities. Exposure to tap water resulted in neural tube defect rates of 10–20%. Rates of cleft palates and rib malformations were 5% and 70% respectively. This research investigated whether analogous findings could be demonstrated in a second animal model, specifically Sprague Dawley and Wistar rats. Female rats were maintained on tap water for 12 weeks prior to breeding and throughout gestation. Resulting embryos were evaluated on day 18 of gestation for fetal weight, placenta weight, and neural tube, palate, facial, ocular, tail, limb and digital malformations. The fetal skeleton was then assessed using tissue clearing and staining with Alcian Blue – Alizarin Red. Both strains of tap water exposed rat embryos demonstrated no significant gross or skeletal malformations at gestational day 18. Lumbar ribs were observed in 8.3% of tap water exposed Sprague Dawley fetuses; however, this is similar to background rates for this strain. These results suggest that rats may be more resistant than mice to the possible tertogen present in tap water. This work was funded by the VA‐MD College of Veterinary Medicine and NIH‐NIEHS R21ES016886.