[Negative report on trichloroethylene-induced pneumatosis cystoides intestinalis in rats].

In recent years it has been suggested in Japan that occupational trichloroethylene exposure will induce primary pneumatosis cystoides intestinalis coli. A series of two experiments were conducted to ascertain the cause-effect relationship between trichloroethylene and pneumatosis as follows: In the first experiment, 12 male rats of Fischer strain were exposed to trichloroethylene at a nearly lethal concentration for 12 wk. Five out of 12 rats died during the experiment, and body weight gain was extremely depressed. However, neither pneumatosis nor histological changes were observed. No changes were observed in 4 control rats as well. In the second experiment, 38 male rats of Sprague-Dawley strain were exposed to 800, 200 or 50 ppm trichloroethylene over a period of 12 wk. Two out of 13 rats of the 800 ppm group died, and body weight gain was suppressed. Mild suppression in body weight gain was also observed in the 200 ppm group. However, pneumatosis was not observed in any rats of trichloroethylene groups. No pathological changes were observed in 13 rats of the control group. The foregoing results suggest that trichloroethylene cannot induce pneumatosis cystoides intestinalis in rats of these two strains. Inasmuch as rats are not prone to develop pneumatosis, the possibility for trichloroethylene to induce this disease in man cannot be denied.