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Hormetic effect of low doses of uranium in rats
The Science of the Total Environment, 101 (1991) 161 Elsevier Science Publishers B. V., Amsterdam - - Printed in Czechoslovakia
161
HORMETIC EFFECT OF LOW DOSES OF U R A N I I M IN RATS
J. PROKE~, S. ~ROMOV~,, K. JOJKOVA, A. ~TAMBERGOV/~, K. VULTERIN, I. LEIFERTOVA, M. L1SA and M. ROOSOV~.
btstitute of Toxicology'., Faculty of General .Medicine, Charles UniversitF, Prague. Czechoslovakia
Hormesis refers to the occurrence of a biphasic dose-response relationship in which higher doses cause an inhibitory effect and lower doses cause a stimulation. Uranium causes changes in the phosphate ion metabolism in rat RBC. An increased metabolic rate at the lowest concentrations of uranium (1.7 mg U/I drinking water) can be interpreted as hormesis. Higher concentrations showed a decrease of the studied metabolism. Linear regression of the relationship between the observed effect and the concentration of uranium shows the responsibility of uranium for it throughout the whole concentration range used. The change of the seemingly beneficial hormetic effect to a negative one (with respect to time and/or concentration of uranium) strongly warns against an optimistic approach to the "hormetic" action at low doses of toxic substances m at least in the case of uranium. It is highly probable, that the increased time as well as the increased dose may lead to similar negative effects in other cases already observed. This fact should be considered in biological monitoring and in providing the M.A.C. values.
0048-9697/91/'$03.50
© 1991 Elsevier Science Publishers B. V.
161
HORMETIC EFFECT OF LOW DOSES OF U R A N I I M IN RATS
J. PROKE~, S. ~ROMOV~,, K. JOJKOVA, A. ~TAMBERGOV/~, K. VULTERIN, I. LEIFERTOVA, M. L1SA and M. ROOSOV~.
btstitute of Toxicology'., Faculty of General .Medicine, Charles UniversitF, Prague. Czechoslovakia
Hormesis refers to the occurrence of a biphasic dose-response relationship in which higher doses cause an inhibitory effect and lower doses cause a stimulation. Uranium causes changes in the phosphate ion metabolism in rat RBC. An increased metabolic rate at the lowest concentrations of uranium (1.7 mg U/I drinking water) can be interpreted as hormesis. Higher concentrations showed a decrease of the studied metabolism. Linear regression of the relationship between the observed effect and the concentration of uranium shows the responsibility of uranium for it throughout the whole concentration range used. The change of the seemingly beneficial hormetic effect to a negative one (with respect to time and/or concentration of uranium) strongly warns against an optimistic approach to the "hormetic" action at low doses of toxic substances m at least in the case of uranium. It is highly probable, that the increased time as well as the increased dose may lead to similar negative effects in other cases already observed. This fact should be considered in biological monitoring and in providing the M.A.C. values.
0048-9697/91/'$03.50
© 1991 Elsevier Science Publishers B. V.