Toxicokinetic modeling of [ 14C]pentachlorophenol in the rainbow trout ( Salmo gairdneri)

• Published in: Aquatic toxicology Vol. 9; no. 1; pp. 59 - 80
• Main Authors: McKim, James M., Schmieder, Patricia K., Erickson, Russell J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 1986; Elsevier Science
• Subjects: Biological and medical sciences; Environmental pollutants toxicology; Fish; Medical sciences; Pentachlorophenol; Toxicokinetics; Toxicology; Water; Toxicokinetics; Fish; Pentachlorophenol; Pollutant; Vertebrata; Excretion; Pisces; Animal; Fresh water; Salmo gairdneri; Metabolism; Labelled compound
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/0166-445X(86)90006-8

An in vivo trout model was used to monitor the major routes and rates of pentachlorophenol uptake and elimination. Rainbow trout exposed to a mean sublethal water concentration (1.0 μg/l) of [ 14C]pentachlorophenol (PCP), a moderately lipophilic, relatively non-persistent environmental contaminant acquired a mean calculated dose of 230 μg/kg per 48 h and a mean measured dose of 212 μg/kg per 48 h. The rate constants determined for the calculated and measured doses were 5.0 ± 0.8 and 4.6 ± 1.1 l/kg per h, respectively. This close agreement between the calculated and measured doses and their rate constants provided further support for the use of this model system in aquatic toxicokinetic studies. A first-order kinetic model and observed data were used to generate fitted and predicted rate constants required for evaluation of first-order kinetics. The fitted first-order uptake-depuration curves for all experimental animals agreed with those observed suggesting first-order kinetics approximated the behavior of whole-body PCP burden. The predicted first-order uptake-depuration curve differed by a factor of 2–3 from that observed, due to the low predicted value used in the model for the steady-state PCP bioconcentration factor (BCF). A BCF of 460 was estimated from the first order simulation model developed from empirical data collected on uptake and elimination of PCP. The dosing time required to reach this steady-state BCF was 280 h. The estimated half-life ( T 1 2 ) was 65 h with approximately 50% eliminated over the gills, 30% in the feces and bile, and 20% in the urine. A depuration period of 280 h was required to eliminate 95% of the steady-state concentration of PCP. Approximately 43% of the 48-h dose of [ 14C]PCP remained in the major organs and muscle tissues of these trout at the end of the 96-h experiment. Of this amount, muscle contained 29% of the total remaining [ 14C]PCP equivalents while the remaining carcass contained 45% of the total remaining [ 14C]PCP. The PCP radiocarbon excreted in the urine was 10% PCP and 90% ‘other’ (metabolite/conjugate), while the bile was 45% PCP and 55% ‘other’ (metabolite/conjugate). PCP and its metabolites were rapidly eliminated from the bodies of fish, which provided for a low BCF. Efficient elimination of PCP should allow vertebrates to tolerate periodic low doses of PCP without toxic effects.