Toxicity of Seven Heavy Metals On Panagrell Us Silusiae: the Efficacy of the Free-Living Nematode as an in Vivo Toxicological Bioassay

The efficacy of the free-living nematode Panagrellus silusiae as a toxicological assay organism was studied using nickel, cadmium, lead, chromium, mercury, copper and zinc as test substances. Acute lethal toxicity values (LC50 values) were obtained for each heavy metal and Panagrellus was found to be highly resistant. When the LC50 values are ordered and correlated, there was no difference between rankings for juvenile (J2) and adult worms. Juvenile worms tend to be slightly more sensitive than adults but this trend was not significant. Testing of the chronic effects of the seven heavy metals revealed that (1) copper, chromium and cadmium effectively blocked growth at all stages of development, (2) the highest soluble concentrations of lead and nickel were without effect on growth of the worms, (3) high concentrations of zinc (>500 mg/l) partially blocked growth and (4) mercury was either lethal (20 mg/l) or ineffective in blocking growth (10 mg/l). When compared with the toxicological data that have been obtained for a number of other organisms, Panagrellus may have some fundamental shortcomings as a model in vivo bioassay organism if the present results with heavy metals pertain to other kinds of toxic substances.