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(P487) Uptake and elimination of dichloroacetic acid by rainbow trout.
Fitzsimmons, Patrick*,1, Hoffman, Alex1, Hammermeister, Dean1, Lien, Greg1, Nichols, John1, 1 US EPA, ORD/NHEERL, Mid-Continent Ecology Division, Duluth, MN, USA
ABSTRACT- Dichloroacetic acid (DCA) is a by-product of drinking water chlorination and is a hepatocarcinogen in rodents. Preliminary results of a chronic testing effort with Japanese medaka suggest the possibility of similar effects in fish. The objective of this research was to investigate the uptake and elimination of DCA by fish. Adult rainbow trout were cannulated from the dorsal aorta, fitted with a urine catheter, and placed in respirometer-metabolism chambers. A latex membrane separating inspired and expired water allowed for a direct measurement of chemical flux across the gills. Fish were exposed to DCA in water (200 mg/L) for 24 h and then allowed to depurate in clean water an additional 48 h. Uptake of DCA by trout was small but measurable. DCA concentrations in blood and urine at 24 h were 6% and 0.8% of water concentrations, respectively. During depuration, DCA concentrations in blood and urine declined rapidly and approached zero within 24 h. No DCA was detected in expired gill water during depuration. DCA had no apparent effect on ventilation volume or oxygen consumption; however, blood pH increased as DCA accumulated during exposure and declined to near pre-exposure levels during depuration. DCA had no effect on blood lactate levels as previously documented in mammals. Ongoing studies are designed to investigate the metabolism of DCA, including the effect of DCA pre-exposure on elimination kinetics. This abstract does not necessarily reflect EPA policy.
Key words: dichloroacetic acid, uptake, kinetics, rainbow trout
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