Uptake, Distribution, and Metabolism of Endothall in Fish

When bluegills were exposed in aquaria to water containing 2 ppm of [¹⁴C] endothall, less than 1% of the herbicide was absorbed by the fish. The maximum concentration of endothall in the fish (0.1-0.2 ppm) was observed 12 hr after treatment; thereafter it did not change significantly up to 96 hr. Radioactivity was detected in viscera, flesh, scales, skin, and head. At all sampling times, the concentration of ¹⁴C residues was highest in the viscera and lowest in the flesh. A small but detectable amount of ¹⁴C was found in the blood 30 min after treatment. The herbicide was also absorbed by the fish when fed through the digestive tract. The fish did not metabolize endothall during the 48 hr after treatment.