A study on geno- and immunotoxicological effects of subacute propoxur and pirimicarb exposure in rats

A 28-day oral exposure with 8.51, 3.40, and 0.851 mg/kg propoxur (PR) and 4 .67, 1.87, and 0.467 mg/kg pirimicarb (PI) was performed in male Wistar rat s, and the occurrence of numerical and structural chromosome aberrations an d the changes in certain immune function parameters (plaque-forming cell (P FC) assay, delayed-type hypersensitivity reaction) and in some basic toxico logical (body weight gain and weights of brain, thymus, lung, heart, liver, spleen, kidneys, adrenals, and popliteal lymph node) and hematological (wh ite blood cells, red blood cells, hematocrit (Ht), mean cell volume of red blood cells (MCV) cell content of the femoral bone marrow) parameters were investigated. The high dose of PR increased the relative liver weight and t he cell content of femoral bone marrow, and all three doses increased Ht an d MCV. The applied doses of PI decreased the relative adrenal weight in a d ose-dependent manner, and its highest dose increased the relative liver wei ght. Among the immune function parameters tested, PFC content of the spleen was decreased by high-dose PR and elevated by high-dose PI, whereas the ma ximum and the time course of the delayed-type hypersensitivity reaction sho wed no changes in this dose range. In the genotoxicological investigations only the high PR dose increased the number of numerical, but not the struct ural, chromosome aberrations. In addition to the changes in relative adrena l weight following PI treatment, the PFC assay showed the highest sensitivi ty for detection of the 4-week exposure with these carbamates. On the basis of our results, the immunotoxicological approach seems to have the same (P R) or higher (PI) sensitivity in early detection of the repeated low-dose e xposure by these carbamates compared to the genotoxicological approach. (C) 2001 Academic Press.