Dynamics of organochlorine compounds in herring gulls (Larus argentatus): I. distribution and clearance of [14C]DDE in free‐living herring gulls (Larus argentatus)

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Abstract
Radiolabelled [14C]DDE was used as a model compound to determine important factors in the clearance of persistent lipophilic compounds in free‐living herring gulls (Larus argentatus). Adult, breeding male and female gulls were dosed orally during incubation and then captured one week and one year later. After one week, [14C]DDE had equilibrated with native DDE in all tissues. The ratios of DDE levels on a lipid weight basis relative to whole body were as follows: muscle, 0.8 to 0.9; liver, 0.5 to 0.7; egg, 0.4; and brain, 0.1. The plasma/whole body lipid partition coefficient was 0.0041 ± 0.0014. The whole body annual average clearance rate was 0.95 ± 0.51 year−1(half‐life = 264 d). Native DDE levels in males were twice those in females, but no differences were found for [14C)DDE after one year. The lower levels in females do not appear to be related to excretion of DDE in eggs or higher monooxygenase activity, but they may be related to differences in feeding ecology. Additional physiological and ecological factors must therefore be included in a proposed two‐compartment (plasma/whole body lipid) model of residue levels in eggs based on experimental data from caged gulls.