Acute toxicity and recovery in the hemopoietic system of rats after treatment with ethylene glycol monomethyl and monobutyl ethers.

Male rats were given ethylene glycol monomethyl ether (EGM) or ethylene glycol monobutyl ether (EGB) po for 4 consecutive days at doses of 100 or 500 mg/kg body wt/day for EGM, and 500 or 1000 mg/kg body wt/day for EGB. Animals were killed on Days 1, 4, 8, and 22 after the final treatment. Both EGM and EGB produced thymic atrophy and lymphocytopenia and, in the case of EGM, neutropenia also. Hemolytic anemia induced by EGB resulted in splenic extramedullary hemopoiesis, hyperplasia of both spleen and bone marrow, and reticulocytosis. Apart from residual slight increases in spleen weight, mean red cell volume, and mean corpuscular hemoglobin at the end of the recovery period, other effects were reversible. With EGM, reduction in the numbers of circulating red cells was only slight. Treatment with EGM also abolished splenic extramedullary hemopoiesis which partially recovered on Day 4, followed by a marked response on Day 8, and return to the moderate control values on Day 22. Femoral bone marrow was hemorrhagic 1 day after treatment with EGM which appeared to be associated with sinus endothelial cell damage. By Day 4 the histologic appearance of the marrow was normal. Testicular atrophy was also produced in EGM-treated animals which persisted for the duration of the experiment. It is concluded that EGM and EGB differ considerably in the spectrum of toxic changes induced, and apart from testicular atrophy, these changes were largely reversible within a short time of the end of treatment.