Dose Range-Finding on the Immunological Evaluation of Trichloroethylene in 10% Emulphor in Female B6C3F1 Mice (CAS No. 79-01-6)
Report Date: June 1992
The following abstract presents results of a study conducted by a contract laboratory for the National Toxicology Program. The findings have not been peer reviewed and were not evaluated in accordance with the levels of evidence criteria established by NTP in March 2009. The findings and conclusions for this study should not be construed to represent the views of the NTP or the U.S. Government.
Trichloroethylene, an important environmental contaminant, had previously been shown to suppress immune function. Trichloroethylene was selected for study with the intent of performing an interaction study with ethanol with the immune system being the target system. Previous studies were performed by the investigators showing that trichloroethylene, administered in the drinking water to CD-mice for 120 days, suppressed selected parameters of the immune system. A range-finding study was performed on trichloroethylene using corn oil as the vehicle and no effect was seen on the immune system. There was concern that the bioavailability of trichloroethylene may be less than with 10% emulphor. Thus, the purpose of this range-finding study was to determine if trichlorethylene would produce an effect on the immune system when delivered in emulphor and, thus, be able to select doses for use in an interaction study with ethanol. In order for the study to be performed within the confines of an interactions study, the period of exposure was set at 14 days and higher doses than were previously reported were used and the route of administration was by gavage. Toxicological parameters assessed were body weight, selected organ weights and selected hernatological indicators. The two immunological assays used to assess immune status were the IgM spleen antibody-forming cell response to sRBC and the cytotoxic T lymphocyte response.
Tricloroethylene, in doses between and including 50 and 800 mg/kg administered for 14 days, did not alter body weight or body weight gain or change the hernatological parameters examined. Trichlorethylene, in doses including and between 100 and 800 mg/kg, caused a dose-related increase in liver weight but no changes in kidney, spleen or thymus weight. Tricloroethylene, in doses between and including 50 and 800 mg/kg administered for 14 days, did not alter the effect on the AFC or CTL responses.
Previous range-finding studies using corn oil as the vehicle and here in using emulphor as the vehicle indicate that TCE, administered by gavage daily for 14 days to female B6C3F1 mice, does not affect the immune system.
Variables different from previously reported effects on the immune system included the method of chemical exposure (gavage vs. drinking water) and the strain of mouse (B6C3F1 vs. CD-1). Range finding studies were. conducted in Female and Male CD-1 mice to determine if there was a mouse strain difference.