Evaluation of the developmental toxicity of linalool in rats

The developmental toxicity of linalool, a widely used fragrance ingredient, was evaluated in presumed pregnant Sprague-Dawley rats (25/group). Oral dosages of 0, 250, 500, or 1000 mg/kg/day linalool were administered by gavage on gestational days 7 to 17. The presence of spermatozoa and/or a copulatory plug in situ was designated as gestational day 0. Rats were observed for viability, clinical signs, body weights, and feed consumption. Caesarean sectioning and necropsy occurred on gestational day 21. Uteri were examined for number and distribution of implantations, live and dead fetuses, and early and late resorptions. Numbers of corpora lutea were also recorded. Fetuses were weighed and examined for gender, gross external changes, and soft tissue or skeletal alterations. There were no maternal deaths, clinical signs, or gross lesions that were considered related to linalool. During the dosage period, mean relative feed consumption was significantly reduced by 7% and mean body weight gains were reduced by 11% at 1000 mg/kg/day. During the postdosage period, feed consumption values at 1000 mg/kg/day were significantly higher than vehicle control values, which corresponded to the increase in body weight gains during this period. Caesarean section and litter parameters, as well as fetal alterations, were not affected by linalool at any of the three dosages tested. On the basis of these data, the maternal no observed adverse effect level (NOAEL) of linalool is 500 mg/kg/day, whereas the developmental NOAEL is > or = 1000 mg/kg/day. It is concluded that linalool is not a developmental toxicant in rats at maternal doses of up to 1000 mg/kg/day.