The following abstract presents results of a study conducted by a contract laboratory for the National Toxicology Program. The findings were not evaluated in accordance with the levels of evidence for reproductive or developmental criteria established by NTP in March 2009. The findings and conclusions for this study should not be construed to represent the views of NTP or the U.S. Government.
Methyl salicylate (MS) is used as a fragrance and flavoring agent, but is lethal at sufficient doses, and is teratogenic in rodents. MS was tested to update and expand the reproductive toxicity database, and used, in part, as a known positive: it was simultaneously tested by two different laboratories at different doses, using the RACB protocol and Swiss mice. Food and water consumptions, clinical signs,and body weights were used in the Task 1 dose-range-finding study to set doses for the continuous cohabitation phase (Task 2) at 100, 250, and 500 mg/kg/d by gavage in corn oil.
Deaths occurred at a rate of 3, 2, 2, and 4 mice/group in the control to high dose groups, respectively. The causes of death varied, and were ultimately not considered due to MS exposure. There were no effects of MS exposure on body weights during Task 2.
There was a 9% reduction in the mean number of litters/pair at the high dose, and a 31% reduction in the number of live pups/litter (from a control value of 11.3, to 7.8 pups/litter). While the viability and sex ratio of these pups was not altered, the pup weight adjusted for litter size in the middle and high dose groups was decreased by 3% and 6%, respectively. MS exposure increased the time to deliver each litter in the high dose group, starting with the second litter, by 2-3 days.
These effects led to Task 3 in an attempt to define the affected sex using the control and high dose groups. MS exposure caused no discernible effects on the proportion of pairs mating or delivering pups, nor on the number, viability, or adjusted weight of those pups. Because only 5 of 17 control X control pairs delivered any young, Task 3 was repeated. Though 7 of 17 pairs delivered young, the same lack of MS effects were observed as in the first trial.
It was decided that the animals should be killed and discarded. No necropsy was performed, and the second generation was not evaluated.
In summary, MS exposure, at dose levels that did not alter body weight or produce adverse clinical signs, adversely affected reproduction (reduced numbers of litters/pair, and number of pups/litter) in Swiss mice.
NTIS # PB85164283