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One of the characteristics of soils in Tatarstan is their low organic matter content. The decrease in soil organic matter is paralleled by declines in soil fertility. One method to reverse this degradation in soil quality is the addition of organic matter. The use of sewage sludge on soils intended for growing of plant seedlings provides an alternative for sewage sludge disposal. Therefore, the evaluation of the feasibility of using compost from the municipal sewage sludge produced in Kazan for the soil restoration and growth of Pinus silvestris seedlings was carried out. The grey forest soil (Haplic Greyzem) was amended with compost at application rate 30, 60 and 90 Mg ha(-1) on a dry matter basis. Organic matter content increased with the increase in sludge amendment. The concentrations of individual heavy metal were below the current limits established for Russia and European countries. Sludge amendments enhanced the germination and the number of the seedlings and the increase were more obvious for the soil with highest sludge treatment. The application of composted sludge to soil was followed by the increase in microbial biomass and basal respiration.

Painting with heavy catalytic gas oil was followed by skin tumor development in 97 (84.3%) mice: benign lesions--21 and carcinoma--76 cases. Pathologic changes in the upper part of the digestive tract were found in 55 out of 106 mice (51.9%): precancerous lesions (leukoplakia, dysplasia and papilloma) in 54 cases and cancer in one animal. Frequency of development of papilloma in the cardia was 27 times that in the esophagus. Multicentric growth was typical of precancerous lesions. Papilloma of the cardia was found in one control animal. Resorptive as well as direct action of gas oil seem to have been the causative factors of the development of precancerous and neoplastic lesions of the upper part of the gastrointestinal tract. The agent found its way into the digestive tract as animals licked each other in the course of the experiments.

The carcinogenic effect of treatment with heavy catalytic gasoil on the skin of 120 albino noninbred mice was studied. Skin tumors arose in 97 of 115 animals (84.3%) which survived until the appearance of the first papillomas. In 21 mice, tumors were benign while cancer developed in 76 animals. 116 visceral neoplasms were detected in 99 animals (93.4%). They were found in the upper part of digestive tract of 57, the hematopoietic and lymphatic tissues of 57 and in the lungs of two animals. The study established a high carcinogenicity of heavy catalytic gasoil matched by early appearance and multicentric growth of tumors as well as rapid generalization of the process.