Aj. Reinecke et al., UPTAKE AND TOXICITY OF COPPER AND ZINC FOR THE AFRICAN EARTHWORM, EUDRILUS-EUGENIAE (OLIGOCHAETA), Biology and fertility of soils, 24(1), 1997, pp. 27-31
Growth rate change in earthworms is considered to be a suitable endpoi
nt when determining sublethal effects. In this study we evaluated grow
th and maturation in the vermicomposting earthworm species Eudrilus eu
ge niae as marker of sublethal toxicity of copper and zinc. We also co
mpared routes of uptake. Apart from exposing worms experimentally for
73 days to contaminated food, a series of contact filter paper tests w
as also performed to determine LD(50) for copper and zinc. Both copper
and zinc at sublethal concentrations affected growth and maturation i
n worms exposed to contaminated food. These worms had a copper content
of 34.5 mu g g(-1) after 73 days and a zinc content of 184.9 mu g g(-
1), showing a differential uptake. Copper was more toxic than zinc. Al
so in the contact test worms did take up more zinc than copper and the
LD(50) (48 h) for copper was 0.011 mg cm(-2) and for zinc 0.066 mg cm
(-2), which translated to body burdens of 6 mu g g(-1) for copper and
131 mu g g(-1) for zinc. Indications were that a regulatory mechanism
existed for both metals. Both metals were taken up through the body wa
ll at a relatively fast rate. This study indicated that the skin was t
he major route of metal uptake. This study also showed a poor relation
between the two types of tests for purposes of evaluating lethality o
f zinc and copper.