Evaluation of the developmental toxicity of annatto in the rat

Annatto, a dye extracted from Bixa orellana seeds, is used as a color additive in butter, cheese and in a variety of other foods as well as in drugs and cosmetics. Toxicological data on annatto and on its main carotenoid pigment bixin are still scarce. In this study we evaluated the developmental toxicity of annatto (28% of bixin). Annatto (0, 31.2, 62.5, 125, 250 and 500 mg/kg body weight/day) was given by gavage to Wistar rats on days 6-15 of pregnancy. Ceasarean sections were performed on day 21. Implantations, living and dead fetuses and resorptions were recorded. Fetuses were weighed and examined for externally-visible anomalies. One-third of fetuses from each litter was examined for visceral anomalies by a microsectioning technique. The remaining fetuses were cleared and stained with Alizarin Red S for skeleton evaluation. No adverse effect of annatto on the mothers was noted. No increase in embryolethality and no reduction of fetal body weight were observed among annatto-exposed rats. Annatto did not induce any increase in the incidence of externally-visible, visceral or skeletal anomalies in the exposed offspring. These findings suggest that annatto was neither maternally toxic nor embryotoxic in the rat. Therefore, the no-observed-adverse-effect level (NOAEL) for annatto-induced maternal and developmental toxicity was 500 mg/kg body weight/day or greater (or > or = 140 mg bixin/kg body weight/day) by the oral route.