Evaluation of the developmental toxicity of chlorinated phenols utilizing Hydra attenuata and postimplantation rat embryos in culture.

Chlorinated phenols (CPs) represent a major component of hazardous oily and wood-preserving wastes that are widely distributed in chemical dumpsites throughout the United States. Pentachlorophenol (C5P) has been reported to be highly embryolethal and embryotoxic in rats. However, data pertaining to the developmental toxicities of other important CPs are limited. In this study, the toxicities of phenol, CP homologues and their isomers, selected phenyl acetates, anisoles, sodium phenates, and tetrachlorobenzoquinones (a total of 38 chemicals) were evaluated using cultures of Hydra attenuata (HA). Developmental hazard index (A/D ratio) was determined for selected test chemicals (i.e., those chemicals which resulted in an early toxic endpoint at the lowest whole-log concentration in the adult hydra assay). These same chemicals were evaluated at equimolar concentration in postimplantation rat whole embryo culture (WEC). HA and WEC studies demonstrated a linear relationship between toxicity and the degree of chlorine substitution with C5P greater than 2,3,4,5-C4P greater than 2,3,5-C3P greater than 3,5-C2P greater than 4-CP greater than phenol. The A/D ratios from the HA assay were approximately 1 for all of the chemicals tested. Findings from the WEC assay indicated similar results based on growth, gross morphology, and DNA and protein content of embryos. The results obtained in the HA and WEC assays suggest that the chlorinated phenols are not potent teratogens. The combination of HA and WEC may facilitate the rapid detection and ranking of hazardous chemicals associated with complex mixtures of chemical wastes.