Dynamics of organochlorine compounds in herring gulls (<i>Larus argentatus</i>): II. A two-compartment model and data for ten compounds

Abstract

Abstract A two-compartment open model using plasma and seasonally variable lipid compartments was developed and validated for several organochlorines in herring gulls (Larus argentatus). Plasma clearance rate constants (k′pc, L·kg−1·d−1), plasma: whole-body lipid partition coefficients (Kpf) and compartment sizes for lipid and plasma were obtained for juvenile gulls injected i.p. with a mixture of p,p′-DDD, p,p′-DDE, hexachlorobenzene, oxychlordane, γ-hexachlorocyclohexane, trans-chlordane, octachlorostyrene, dieldrin, mirex and photomirex. Concentrations in plasma were determined at 11 time points during the 239-d study, and whole-body contaminant burdens and lipid weights were determined at 3 time points. Mean Kpf for p,p′-DDD and p,p′-DDE (0.0038 ± 0.0002) was different from that of the other organochlorines (0.0058 ± 0.0005, n = 7). The latter values were close to the expected fraction lipid in plasma, indicating a simple thermodynamic partitioning between lipid pools in adipose tissue and plasma. Plasma clearance rate constants ranged from approximately 0.04 L·kg−1·d−1 for slowly clearing organochlorines such as p,p′-DDE and mirex to 500 L·kg−1·d−1 for rapidly clearing γ-hexachlorocyclohexane and trans-chlordane. Simulations using these parameters and lipid weight regimes for individual experimental birds tracked observed plasma concentrations and final body burdens closely. Simulated whole-body half-lives of organochlorines in wild adult gulls were similar to those published for other species.