The following abstract presents results of a study conducted by a contract laboratory for the National Toxicology Program. The findings may not have been peer reviewed and were not evaluated in accordance with the levels of evidence criteria established by NTP in March 2009. For more information, see the Explanation of Levels of Evidence for Developmental Toxicity. The findings and conclusions for this study should not be construed to represent the views of NTP or the U.S. Government.
A retrospective comparison of data for two test article vehicles commonly used in teratology studies suggested that embryo/fetal development might be adversely affected by corn oil administration during organogenesis (Kimmel et al.. 1985). Thus, in the present study maternal status and embryo/fetal development were evaluated in timed-pregnant CD-l mice (n = 53-55 confirmed pregnancies per group) treated concurrently with distilled water or corn oil. Distilled water was administered by gavage at a dose volume of 10 ml/kg; corn oil was administered by gavage to two additional groups of mice at 3 or 10 ml/kg. Treatment, once per day for both test substances, was given on gestational days 6 through 15.
Females were weighed and observed daily for clinical signs during treatment. Maternal food and water consumption were measured throughout gestation. At sacrifice on gd 17, maternal liver was weighed. In addition, the uterus of each dam was weighed, and the number and status of uterine implantation sites were recorded. Each live fetus was weighed, sexed, and examined for external, visceral, and skeletal malformations.
No adverse effects of CO treatment upon maternal body weight or body weight gain were observed. Maternal absolute liver weight and relative liver weight were significantly decreased in the 10 ml/kg CO group compared to the DW group. Maternal food consumption for mice in the 10 ml/kg CO group (relative and/or absolute) was slightly decreased on gd 12-15 and significantly depressed on gd 15-17 as compared to the DW group.
No adverse effects upon embryo/fetal growth or viability were noted in the 10 ml/kg CO group; the percent dead fetuses per litter was marginally but not significantly decreased. There was no adverse effect of treatment on the incidence of malformations. The incidence of a skeletal variation, extra lumbar ribs, was marginally but not significantly increased in the 10 ml/kg CO group.
The results of the present study are in contrast to earlier findings and warrant the conclusion that administration of CO at 3 or 10 ml/kg to pregnant CD-l mice during the period of major organogenesis had no significant adverse effect on embryo/fetal development relative to distilled water (10 ml/kg).