Biochemical and developmental effects of dietary exposure to polychlorinated biphenyls 126 and 153 in common tern chicks (Sterna hirundo)

Abstract

Abstract-Effects of PCBs were studied in common terns (Sterna hirundo).Hatchlings from eggs collected from Dutch breeding colonies and incubated artificially were raised to an age of 21 d. The birds were fed fish spiked with PCB 126 alone or in combination with PCB 153 (1:1,000), resulting in concentrations in the food ranging from 0.01 to 1.2 ng toxic equivalents (TEQs)/g wet weight.The most sensitive effect parameter was induction of hepatic CYP1A-associated ethoxyresorufin-O-deethylation (EROD) activity, and a nonlinear concentration-effect relationship could be determined with the TEQ concentration (r ϭ 0.967, p Ͻ 0.001). Induction of pentoxyresorufin-O-depenthylation and methoxyresorufin-O-demethylation activities was observed at dose levels similar to those that induced EROD activity. The estimated lowest-observed-effect level for induction of CYP1A in the common tern was approx. 25 ng TEQ/g liver lipid, which was caused by concentrations in the food of approx. 0.6 ng TEQ/g fish wet weight. At these concentrations, a 50% reduction in plasma total thyroxine compared with controls also was observed. Concentrations of plasma total thyroxine were negatively correlated with hepatic TEQ concentrations (r ϭ 0.523, p Ͻ 0.01), but the shape of the nonlinear concentration-effect relationship did not allow determination of a lowest-observed-effect level. No changes were found for hepatic hydroxylation of testosterone. Bursa weight decreased proportionally to hepatic concentrations of TEQs (r ϭ 0.433, p Ͻ 0.05) and showed a similar sensitivity as that observed for EROD activity. Concentrations of TEQs in The Netherlands are approx. 0.1 ng TEQ/g wet weight fish, which is approximately six times lower than the lowest-observed-effect level for CYP1A induction in terns as estimated in this study. It is concluded that no overt effects on growth and development in the common tern are expected with this background exposure during the posthatch period.

Polychlorinated -dibenzo-p-dioxins/furans and -dioxin-like biphenyls in eggs of common terns from lime island, St. Mary's river, Michigan, USA

“…Concentrations of PCDD/DFs in this study were greater or similar to, yolk sacs of hatchling common terns from The Netherlands and Belgium, and eggs of Forster's terns (Sterna forsteri) from Green Bay, Wisconsin, USA, but greater than eggs of Forster's terns from Lake Poygan [24][25]32]. Peregrine falcon (Falco peregrinus) eggs from California, USA had much lower concentrations of PCDD/DFs than this study [38], however, they had greater TCDF levels than TCDD.…”

“…Overall, there are no specific differences between affected and good eggs. Common tern eggs from The Netherlands and North Sea, respectively, demonstrated insignificant developmental effects of chicks during in ovo exposure of PCBs and no correlation to organochlorine pesticides or PCBs [19,25].…”

“…Severe reproductive failure has been documented in common terns in recent years [19][20][21][22][23][24][25][26][27]. Studies also reported observations of bill deformities in common terns and suggested that POCs played a vital role for these effects [19,[21][22][23][24][25][27][28][29]. Although, p,p 0 -DDE effects on eggshell thinning and population declines in birds are well documented, current DDE concentrations are below effective concentrations in the Great Lakes Basin [30][31].…”

“…Although, p,p 0 -DDE effects on eggshell thinning and population declines in birds are well documented, current DDE concentrations are below effective concentrations in the Great Lakes Basin [30][31]. However, concentrations of POCs continue to be at levels associated with developmental effects, endocrine disruption, embryotoxicity, immunotoxicity, teratogenesis, morphological aberrations, alterations in plasma concentrations of vitamin A/thyroid hormones, and induction of hepatic cytochrome P4501A1 activity [19,[21][22][23][24][25][32][33].…”

Bioaccumulation of PCBs in Arctic seabirds: influence of dietary exposure and congener biotransformation

“…The present study's seabird TEQ values were 100-200 times lower than the lowest observable effect level (LOEL) for CYP1A induction (EROD) in common terns (Sterna hirundo) (25 ng g ÿ1 TEQ lipid weight liver) (Bosveld et al, 2000). Even though the effect threshold varies depending on species and sample matrix, the presently investigated Arctic seabirds therefore seem well below the threshold levels for effects mediated through the Ah-receptor.…”