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.
Camphor is a very common constituent of over-the-counter medications used to relieve muscle aches, nasal congestion, and discomfort from cold sores. Ingestion of CAM can cause severe toxicity in humans. Because of the large population at risk for CAM exposure, and since it readily crosses the placenta, CAM was evaluated as a potential developmental toxicant. CAM (O, 50, 200, or 400 mg/kg/day) was administered in corn oil by gavage to pregnant rabbits during the major period of organogenesis (gd 6-19). The top dose of 400 mg/kg/day was based on a preliminary dose range finding study which found 500 mg/kg/day CAM caused 60% maternal mortality. Does were monitored for physical and clinical signs of toxicity. On gd 30, fetuses were examined for effects of CAM on growth, viability, and morphological development.
There was no maternal mortality in any of the experimental groups. Maternal body weights in the CAM-treated groups were comparable to controls at all gestational ages. However, maternal weight gain tended to decrease with increasing dose of CAM. Maternal food consumption in all three CAM groups was similar to controls throughout gestation. Examination of the uterine contents revealed that CAM had no effect on fetal growth, viability, or morphological development.
The results from this study indicate that CAM is neither developmentally toxic nor toxic to the doe at doses as high as 400 mg/kg/day.