Prenatal toxicity of xylene.

Prenatal inhalation toxicity of xylene (industrial mixture of isomers) was studied in experiments of white Wistar rats exposed daily (6 hours a day, 5 days in a week) to concentrations of 10, 50 (MAC for xylene in the air of work environment in Bulgaria) and 500 mg.m-3 throughout the period of gestation from the first to the 21st day. Both routine teratological indices and biochemical and physiological methods of observation were used to evaluate the integrity of the individual organs - liver, brain, lungs and myocardium of the generation in the postnatal period of development. In concentrations of 50 and 500 mg.m-3, xylene exhibits pronounced embryotoxic and teratogenic effects. Postimplantation embryonal mortality increases, the process of physical development of the fetus is delayed, the incidence of induced anomalies of internal organs (hydrocephalus, microphthalmia, intracerebral haematomas, haemorrhages in the liver) is enhanced, the processes of ossification of the sternum and the skull are impaired. In concentrations of 50 and 500 mg.m-3, xylene causes disturbances in postnatal development of F1 generation. The concentration of 50 mg.m-3 is the threshold of the embryotropic effect of the solvent. Measures for the protection of women at work are proposed to reduce industrial hazard of developing antenatal pathology in the newborn of workwomen in xylene works.