Dose–response functions were determined in adult and preweanling
male rats for four OPs for which there were no publically available
data regarding age-related sensitivity, and to test the accuracy of predictions from our in vitro assay (Moser and Padilla, 2011). Based on
brain ChE inhibition and acute toxicity (lethality), mevinphos was
clearly more toxic, up to 4-fold, to the young rat. On the other hand,
monocrotophos, dicrotophos, and phosphamidon were somewhat
more toxic in the pups, but the magnitude of the differences was
lower, about 2-fold or less. In general, these findings agree with the
limited information on metabolism and detoxification of these OPs.
The current results underscore other findings that age-related
differences in sensitivity are chemical-specific.