Aquatic toxicity tests were conducted with atrazine, carbon tetrachloride, chloroform, methylene chloride, trisodium nitrilotriacetic acid (NTA), and phenol. Each compound was administered to developmental stages of three to five amphibian species. Exposure was initiated at fertilization and maintained through 4 days posthatching. Test responses included lethality and teratogenesis. Different amphibian species exhibited varying degrees of tolerance to the selected compounds. Greatest tolerance usually was observed for the more broadly adapted semi-aquatic and terrestrial species (e.g., Bufo americanus, Bufo fowleri). The more sensitive amphibians usually included those species which normally are restricted to aquatic or moist habitats (e.g., Rana catesbeiana, Rana pipiens).
Median lethal concentrattons (mg/1) determined at 4 days posthatching ranged from 0.41 to \u3e 48 for atrazine, 0.90 to 2.83 for carbon tetrachloride, 0.27 to 35.14 for chloroform, 17.78 to \u3e 32 for methylene chloride, 39.3 to 252.3 for NTA, and 0.04 to \u3e 0.89 for phenol. The most toxic compounds always included phenol, carbon tetrachloride, and atrazine, and the least toxic consistently were NTA and methylene chloride. for three chlorinated alkanes, including methylene chloride (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4), toxicity increased with chlorination. Toxicity of the different compounds was further characterized by calculating concentrations which produced embryo-larval lethality or teratogenesis at frequencies of 10% (LC10) and 1% (LC1). On the basis of LC1 values, Hyla crucifer, Rana catesbeiana, and Rana pipiens generally exhibited sensitivity equal to or slightly greater than that observed for embryolarval stages of the rainbow trout
