Yolk retinoids (vitamin a) in eggs of the herring gull and correlations with polychlorinated dibenzo‐p‐dioxins and dibenzofurans

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Abstract
Little is known of the combined effects associated with chronic, low‐level exposure of wildlife to the polyhalogenated dibenzo‐p‐dioxins, dibenzofurans, certain biphenyls and other related compounds. To examine possible effects upon egg yolk retinoids, herring gull(Larus argentatus)eggs were collected at early (i.e., days 2–12) and late (i.e., approximately day 20) phases of incubation. Analysis of egg yolks by reversed‐phase high‐performance liquid chromatography revealed compounds that comigrated with all‐trans‐retinol and all‐trans‐retinyl palmitate standards. The retinol concentration and the molar ratio of retinol to retinyl palmitate changed significantly between the early and late phases of incubation. Within the 2‐ to 12‐d period of incubation, however, retinoid values were constant. Gull eggs were collected from two breeding colonies on the Great Lakes in 1986 and from five colonies in 1987. In 2‐ to 12‐d eggs, retinol and retinyl palmitate concentrations were significantly different between gull colonies. The molar ratio of retinol to retinyl palmitate was significantly different between colonies and correlated with several indices of polychlorinated dibenzo‐p‐dioxin and dibenzofuran concentrations quantified in gull eggs from these collection sites. Significant correlations existed between the molar ratio of retinoids and (a) 2,3,7,8‐TCDD concentration, (b) toxic equivalents of PCDDs and PCDFs and (c) the sum of PCDD and PCDF concentrations. These results are discussed in the context of sensitive, bioeffects monitoring.