Experimental study of combined effect of solvents and noise.

Experimental studies of simultaneous exposure of the organism to chemical compounds and other unfavourable occupational and social factors are of great importance for the understanding of the mechanisms of combined effect and the detection of the dose-effect dependence. On a total number of 2000 made Wistar rats, 7 series of experiments were carried out in which the combined effect of solvents widely used in industry (acetone, carbon disulphide, trichloroethylene) and noise at varying levels (1-2, 10 Limchr for the solvents and 85, 95 dB A for noise) and duration of exposure (1 1/2-2 and 4 months) was studied. Biological effect was evaluated dynamically using a complex of indices reflecting the state of the principal systems of the organism--the nervous, cardiovascular, endocrine and immune systems. Results of the studies were analysed using a linear model by means of which the types of interaction of the factors could be classified. In all the series of experiments, an antagonistic type of combined effect was found to predominate according to most different indices. The mechanisms underlying the antagonistic interaction between the solvents showing narcotic effect, and noise are discussed.