In the aim to mitigate the toxicity of cadmium polluted in water environment, the organic chemicals which were considered to chelate with cadmium, were investigated in rearing Oryzias latipes. The survival ratio of the fish reared in 3 × 10
-5 M Cd was 50% after 21.5 h, and this concentration was applied through this experiment. Fourteen sodium salts of 10
-4 M organic acids prolonged the longevity of the fish.Tricarboxylates were the most effective. Four chelating agents were also effective and EDTA was the most. Glutaminate was little effective, whereas another amino acid cysteine decreased the survived. Three mitigative chemicals, EDTA, cis-aconitate (cis-Aco) and iso-citrate (iso-Cit) and the promoting chemical, cysteine (CySH) were investigated again at the relative concentrations shown in Table 1. The effects were shown obviously at above 0.5 relative concentrations. The effect of EDTA remained even after 48 h, whereas those of tricarboxylates did not. Co-existence of EDTA with cis-Aco and with iso-Cit seemed to increase the effects of these tricarboxylates. Co-existence of EDTA with CySH cancelled the effect of this amino acid and, at high relative concentration, a mitigative effect was observed.
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