SEDL / STP / STP891-EB / STP33593S

Bioconcentration of Four Chlorinated Dioxins By Rainbow Trout and Fathead Minnows

Muir, DCG
Research scientist and chemical technologist, Freshwater Institute, Winnipeg, Canada

Yarechewski, AL
Research scientist and chemical technologist, Freshwater Institute, Winnipeg, Canada

Webster, GRB
Professor, University of Manitoba, Winnipeg,

Pages: 15    Published: Jan 1985

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Abstract

Accumulation of four ¹⁴C-labelled chlorinated dibenzo-p-dioxins (1,2,3,7-tetrachloro- (T⁴CDD), 1,2,3,4,7-pentachloro- (P⁵CDD), 1,2,3,4,7,8-hexachoro- (H⁶CDD), and 1,2,3,4,6,7,8-heptachloro- (H⁷CDD) isomers) from water by rainbow trout fry (Salmo gairdneri) and fathead minnows (Pimephales promelas) was studied using a 5-day exposure period followed by a 24-day elimination phase. Water concentrations of these hydrophobic compounds (measured after centrifugation) ranged from 0.005 to 0.10 ng/mL during the fish exposures. Equilibrium bioconcentration factors calculated by use of a two-compartment kinetic rate model ranged from 810 for P⁵CDD to 2278 for H⁶CDD in rainbow trout and from 515 for H⁷CDD to 4232 for H⁶CDD in fathead minnows. Elimination rates of T⁴CDD and P⁵CDD isomers were similar and rapid, with half-lives of total radioactivity averaging about 2.6 days in trout fry and 3.0 days in minnows. Half-lives of total ¹⁴C for H⁶CDD and H⁷CDD were also similar but much longer than the other two isomers averaging about 16 days in rainbows and 20 days in fatheads. Low bioconcentration by both species was attributed to the high proportion of total radioactivity in water apparently unavailable to the fish because of association with suspended and dissolved material and to poor membrane transport.