Toxicity of three preparations of pentachlorophenol to fathead minnows -A-comparative study

Abstract

The toxicity of three samples of pentachlorophenol (PCP) containing various impurities was evaluated in 90-d, partial life-cycle toxicity studies with fathead minnows (Pimephales promelas Rafinesque). Samples of purified PCP, Dowicide EC-7, and a composite of commercial PCP were used in the studies. The exposure concentrations were 10 to 142 μg/L of the purified PCP; 8 to 139 μg/L of the Dowicide EC-7; and 6 to 121 μg/L of the commercial composite of PCP. The purified PCP contained relatively high amounts of chlorinated phenoxyphenols; Dowicide EC-7 contained more types of impurities, but generally at lower concentrations than in either the purified PCP or the commercial composite; and the commercial composite contained relatively large quantities of hexachlorobenzene, chlorinated phenoxyphenols, chlorinated dibenzodioxins, and chlorinated dibenzofurans. Concentrations of the purified PCP equal to or greater than 85 μg/L reduced the growth of the fathead minnows but did not adversely affect survival. Dowicide EC-7 concentrations as high as 139 μg/L did not adversely affect growth or survival of fathead minnows. The commercial composite of PCP reduced growth at concentrations of 13 μg/L or higher and reduced survival at concentrations of 27 μg/L or higher. Degeneration of the fins and opercles, and malformations of the anterior regions of the skull were also noted in fathead minnows exposed to the commercial composite of PCP. Impurities clearly increased the toxic effects of PCP in fathead minnows.