The health of children from different districts of the town of Kstov, Nizhegorod [correction of Nizhni Novgorod] Province, that has developed petrochemical industry, was studied. The study demonstrated that the children living in a ecologically poor area had high sensitization to benzene derivatives and a high incidence of allergic diseases. Benzene derivatives, such as trimethylbenzene and tetramethylbenzene), have not only a property of sensitizing, but also nonspecific toxic effects on the children.