Static renewal bioassays were performed with four polychlorinated biphenyls, including Capacitor 21 and Aroclors 1016, 1242, and 1254. Each compound was used to treat embryo-larval stages of the rainbow trout (Salmo gairdneri), channel catfish (Ictalurus punctatus), goldfish (Carassius auratus), redear sunfish (Lepomis microlophus), leopard frog (Rana pipiens), Fowler\u27s toad (Bufo fowleri), and American toad (Bufo americanus). Developmental stages of the trout were the most sensitive, with LC50 \u27s at 4 days posthatching of 0.3, 1.0, 1.1, and 1.6 μg/l for Aroclors 1254, 1242, 1016, and Capacitor 21, respectively. LC1\u27s ranged between 0.009-0.011 μg/l. Fowler\u27s toad was the most tolerant species, and LC50 \u27s varied from 3.7-28.0 μg/l. Toxicity of the PCB\u27s generally increased with percent chlorine substitution.
Bioassays also were conducted with dioctylphthalate (D0P), diisononylphthalate, and Dow Corning 561 silicone, three products proposed as replacements for PCB\u27s. Embryos and larvae of the channel catfish, redear sunfish, leopard frog, and Fowler\u27s toad were exposed through 4 days posthatching. Catfish was the most sensitive species, and sunfish was the most resistant. Based on LC50 values, replacement products were found to be 2-5 orders of magnitude less toxic than PCB\u27s.
Continuous flow embryo-larval bioassays were performed on Capacitor 21 and DOP. Test species included redear sunfish, rainbow trout, and largemouth bass (Micropterus salmoides). Paralleling results from static renewal tests, flow-through data reflected a vast difference in toxicity between PCB\u27s and potential replacements, and good data correlation was achieved between the two bioassay procedures
