Cadmium and lead kinetics during experimental contamination and decontamination of the centipede Lithobius forficatus L.

Abstract

Kinetics of cadmium decontamination in Lithobius forficatus, performed in autumn experiments showed a decrease in Cd level, from about 30 mg/kg dw at the beginning of the experiment to about 12 mg/kg dw ten weeks later. Kinetics of cadmium contamination in animals showed in a first time a dramatic increase in Cd levels (up to a mean 80 mg/kg dw). Then a regular decrease was observed, although the animals were regularly fed with cadmium contamined larvae. Difference between animals fed or not with cadmium containing diet ranged from 18 mg/kg dw to only 8 mg/kg dw at the end of the experimental series. Experiments conducted either in autumn or in spring showed comparable aspects in the evolution of level curves, if not the same values. Natural decontamination of lead in animals showed results that were not convincing, depending at least of the dose level present in animals. Therefore, when experimental intoxication was performed, a natural detoxification process took place where Pb levels in animals first increased dramatically and then regularly decreased which was assumed to be evidence of an active excretion. Moreover, animals living in an artificially lead polluted soil and fed with lead-free diet also showed a rapid increase in Pb level followed by a plateau. From these studies, it can be concluded that these centipedes can be contaminated both by food intake and by ion regain through the tegument.