Comparison of polychlorinated dibenzodioxin levels with hepatic mixed‐function oxidase induction in great blue herons

Abstract

As part of the Canadian Wildlife Service monitoring of great blue herons in British Columbia, eggs were collected from three colonies with low, intermediate, and high levels of PCDD and PCDF contamination: Nicomekl, Vancouver, and Crofton, respectively. One egg from each nest was used for chemical analysis by GC-MS; the others were hatched. Liver microsomes were prepared from the heron chicks and used for determination of cytochrome P-450-dependent activities. No erythromycin N-demethylase activity was found in any sample. Ethoxyresorufin O-dealkylase activity in the Nicomekl group was similar to that in pigeons, a control altricial species. The ethoxyresorufin activity in the herons from the Crofton colony was 2.6-fold higher than in the Nicomekl group. The Vancouver colony was intermediate. No difference among the three heron colonies was found in pentoxyresorufin O-dealkylase activity, although levels were 20-33 times that in the pigeon. Chemical analysis was carried out on paired heron eggs. Vancouver and Crofton eggs contained 13.5 and 21 times the levels of 2,3,7,8-TCDD compared to the Nicomekl group. The Crofton eggs contained higher levels of several other contaminants also. A highly significant correlation (p less than .001) was found between ethoxyresorufin O-dealkylase and 2,3,7,8-TCDD concentrations. The correlation coefficient did not change when ethoxyresorufin O-dealkylase was compared to total chemical contamination using several toxic equivalency factors. Multiple regression analysis resulted in only one predictor variable for ethoxyresorufin O-dealkylase: 2,3,7,8-TCDD.

β-carotene and retinoids in eggs of Great Blue Herons (Ardea herodias) in relation to St Lawrence River contamination

“…These values are marginally lower than the mean colony levels of 5.9 to 10.6#g g-~ reported for the same species collected from various Quebec colonies in 1979 (Laporte 1982). Comparable values in the low p.p.m, range were detected in Great Blue Heron eggs from the Tennessee Valley and Texas (southern United States) as well as British Columbia (west coast of Canada) (Mitchell et al 1981;Fleming et al 1984;Bellward et al 1990).…”

Biological effects of polychlorinated dibenzo‐p‐dioxins, dibenzofurans, and biphenyls in bald eagle (Haliaeetus leucocephalus) chicks

“…As reported previously for great blue heron chicks in the Strait of Georgia [17,19] regression of the biochemical endpoints against 2,3,7,8-TCDD or 2,3,7,8-TCDF produced the best coefficients of determination (r 2 ). This contrasts to data for other avian species and locations, where non-ortho and mono-ortho PCBs or TEQs, commonly using Safe's [5] TEFs, provided the best statistical fit to CYP1A parameters [15,19,59].…”

“…PCBs have been reported to cause accumulation of porphyrins in chick embryo hepatic cell cultures [62] and in liver and other tissues of adult birds of common laboratory species [63] but not apparently in captive predatory birds [64]. In previous field studies, hepatic porphyrins were elevated in adult herring gulls from more polluted areas of the Great Lakes [61] but not in great blue heron embryos exposed to elevated PCDDs and PCDFs [17].…”

“…Previous studies in the British Columbia's Strait of Georgia used the great blue heron (Ardea herodias) as a sentinel species to assess wildlife exposure to PCDDs and PCDFs from bleached-kraft pulp mill and other forest industry sources that dominate industrial activity in that area [16]. Episodes of poor breeding success in the late 1980s were associated with sublethal effects on embryos, including edema, reduced body weight, and EROD (ethoxyresorufin O-deethylase) induction, which correlated well with TCDD levels [17][18][19]. Efforts by the pulp and paper industry to reduce PCDD and PCDF formation and release in effluents resulted by 1991 in significant decreases in contamination of heron eggs and improvements in the condition of embryos [19,20].…”

Toxicity of 2,3,7,8-Tetrachlorodibenzo-p-dioxin to Several Ecological Receptor Groups: A Short Review

“…Data from studies on herring gull and great blue heron (Hallet and Brooksbank, 1986;Cook et al, 1993;Bellward et al, 1990;Hart et al, 1991) indicate that stable populations are maintained in wild colonies, even though TCDD is present at concentrations in eggs between 200 and 500 pg/g. In turn, toxic effects at the individual level are associated with concentrations above 100 pg/g.…”