The Importance of Synergistic Interaction at Low Intensity of Physico-Chemical Agents

Experimental data obtained for the simultaneous action of hyperthermia with different physical or chemical agents on various cellular systems give evidence that the lesser the intensity of physical factor or the concentration of chemical agents, the lower the temperature has to be used to provide the highest or a definite level of synergistic interaction. On this basis, it is inferred that the synergism may take place at small intensities of harmful environmental factors existing in the biosphere. Hence, the assessment of health or environmental risks should take into account the synergistic interaction between harmful agents. INTRODUCTION Combined exposures are an essential feature of modern life. It is well known that almost all physical and a wide array of chemical harmful agents, both natural and man made, are capable of interacting with each other in a synergistic manner when the final biological effect exceeds the sum of individual effects produced by interacting agents. Therefore any risk assessment must consider the question whether combined