Effects of cadmium on salamander survival and limb regeneration.

INTRODUCTION The need for sensitive aquatic toxicity tests is growing with the increasingly greater number of pollutants disposed of in waterways. We have initiated studies to determine whether the salamander, Notophthnlmus \iridescens. may be a useful animal model for bioassays on water toxicity. The salamanders used in this study are aquatic amphibians which have the ability to regenerate their limbs. The process of limb regeneration has been shown to be sensitive to a number of teratogenic agents such as thalidomide, beryllium, and trypan blue (Bazzoli et rrl., 1977). Salamanders might serve as animal models in the bioassay of aquatic pollutants if limb regeneration could be used as a quantitative, sensitive index of toxicity. The compound we chose to examine with this animal model was cadmium acetate. Although cadmium is found in natural waters at low concentrations, industrial and sewage treatment wastes contribute significant amounts of cadmium to waters near urban areas (Fleischer et NI., 1974). Cadmium is lethal to fish at concentrations in the range of lo100 ppb, depending on the species and on the length of experimental exposure (Ball, 1967; Pickering and Gast, 1972: Cearley and Coleman, 1974). Concentrations within and in excess of this range may be expected to occur in surface waters near point sources of cadmium contamination. Sublethal concentrations of cadmium may inhibit fish reproduction and decrease the survival rate of developing embryos (Rehwoldt and Karimian-Teherani. 1976; Pickering and Gast, 1972). Spinal deformities have been reported in the offspring of fish maintained in water containing cadmium (cited in Rehwoldt and Karimian-Teherani, 1976). The purpose of this study was to determine whether there is a dose-response relationship between cadmium in the water and (a) salamander death rate or (b) time of onset, rate. and quality of salamander forelimb regeneration.