BEHAVIORAL TERATOLOGY AND DOMINANT LETHAL EVALUATION OF NITROUS-OXIDEEXPOSURE IN RATS

Epidemiological studies have suggested that spontaneous abortion may b e increased in medical personnel following the sort of chronic low-lev el exposure to the anesthetic gas nitrous oxide (N2O) seen in surgical or dental operatories. These results are supported by some, but not a ll, animal studies, and results are less well established at low expos ure levels. Behavioral effects in exposed animal offspring have also b een observed, but again not in all studies. To further examine this pr oblem, we conducted the present experiments. Adult male or female rats were exposed to trace concentrations of N2O (0%, 0.1%, 0.5%, or 1.0% in air) for 6 h daily either throughout gestation (females) or for 9 w eeks (males). Offspring from treated adults were subjected to an exten sive behavioral test battery. There were no clear dose-response effect s on any of eight behavioral tests for any offspring. Maternal and off spring weights were normal from conception through adulthood. Addition ally, we studied effects of N2O on male fertility by mating treated ma les with untreated females and examining uterine contents. There was n o evidence for a substantial decline in fertility of exposed males, al though there was a small dose-related trend for resorptions to increas e and live births to decrease with increasing paternal N2O exposure. T hese results suggest that there is little alteration in male or female fertility following chronic exposure to low levels of N2O. There are also no significant long-term behavioral alterations in offspring expo sed gestationally to trace levels of N2O via dam or sire.