Hematological alterations in rats from xylene and benzene

Benzene and xylene are used by the chemical industry as raw materials for the manufacturing of paints, insecticides, gums, resins and other compounds. Through its myelotoxic actions, benzene produces hematologic changes ranging from pancytopenia to total bone marrow aplasia. The present investigation studied the possible effects of xylene on rat peripheral blood and compared these effects to those produced by benzene. Thirty-six male Wistar rats were injected s.c. with 2 ml benzene, xylene or saline/kg body weight 3 times a week at 2-3 d intervals for 5 w. The animals were lightly anesthetized and blood was collected by puncture of the retro-orbital plexus before the first administration of the solvents on d 7, 14, 21 and 35 of dosing, and 14 d after dosing was discontinued. Xylene induced leukocytosis as an increase in absolute neutrophil numbers, whereas benzene caused leukocytopenia due to decreases in absolute lymphocyte number. The 2 solvents reduced erythrocyte counts, hematocrit and hemoglobin. Platelet counts were high throughout the dosing with benzene and xylene. Fourteen d after discontinuation of xylene dosing, the rats recovered their initial hematologic values, whereas the animals dosed with benzene did not fully recover leukocytes and erythrocytes. The intoxications with benzene and xylene were not solely hematologic since there was also growth retardation, as shown by reduced weight gain, which did not recover after dosing ceased.