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 The findings have not been peer reviewed and were not evaluated in accordance with the levels of evidence criteria established by NTP in March 2009.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. The purpose of this range-finding study was to determine if the male CID-1 mouse was sensitive to trichloroethylene with respect to targeting the immune system and, if immunosuppression was observed, to select doses for use in the interaction study. In order for the study to be performed within the confines of an interaction study, the period of exposure was set at 14 days and higher doses than were previously reported were used. The route of administration was by gavage. Emulphor was selected as the vehicle because it was the vehicle used in previously published studies. Toxicological parameters assessed were body weight and selected organ weights. The immunological assay used to assess immune status was the immunoglobulin M spleen antibody-forming cell response to sheep erythrocytes.
Tricloroethylene, in doses of 125, 250, and 500 mg/kg administered daily for 14 days, did not alter body weight or body weight gain. Trichlorethylene, in the doses indicated, caused a doserelated increase in liver weight and decrease in thymus weight. However, no individual dose group reached statistical significance at p < 0.05. Triclo ro ethylene, in the doses indicated, did not affect the spleen IgM AFC response to sRBC.
From range finding studies, long term exposure may be required to produce immunosuppression, i.e., 13 weeks. Because of the nature of interaction studies, trichlorethylene is not a good candidate chemical to carry out interaction studies.