Emesis in monkeys following exposure to ionizing radiation.

There were 129 male rhesus monkeys (Macaca mulatta) exposed to prompt radiations (neutron/gamma = 0.4 and pulse width = 50 ms) ranging from 700 to 5600 rad (midhead dose). The animals were fasted 18 h preexposure and observed for incidence of vomiting for 2 h postexposure. For doses less than 1000 rads the number of animals that vomited increased directly with dose. Above 1000 rads, the number of animals that vomited decreased with increasing dose. The total number of vomits per dose group followed a nearly identical pattern to the incidence of emesis. In all dose groups, most of the emetic episodes occurred between 20 and 50 min postirradiation.