Cesh L.S.,Simon Fraser University |
Elliott K.H.,University of Manitoba |
Quade S.,Carleton University |
Mckinney M.A.,Carleton University |
And 7 more authors.
Environmental Toxicology and Chemistry | Year: 2010
Polyhalogenated aromatic hydrocarbons are global contaminants that are often considered to be endocrine disruptors and include 1,1-dichloro-2,2-bis(4- chlorophenyl)ethylene (p,p'-DDE), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs). The present study examined these compounds and their hydroxylated metabolites or analogues and relationships with circulating thyroid hormones and retinols in plasma from nestling and adult bald eagles in British Columbia, Canada, and California, USA. We also compared our results with published data. Thyroxine (T4) decreased with σPCB and CB153 in nestling bald eagles, which was congruent with results from nine of 14 other published avian laboratory and field studies. Free thyroid hormone levels also decreased with CB-153 and hydroxylated PCBs (OH-PCBs). Retinol increased with CB118 and CB180 in nestling eagles, decreased with OH-PCBs in a subset of nestlings, and decreased in 7 of 12 PCB published studies. Thyroxine decreased with p,p'-DDE for nestlings and with data reported in one of five other published studies. In our samples, plasma retinol, triiodothyronine (T3), and T4 were independent of σPPBDEs, whereasσOH-PBDEs were weakly but significantly correlated with increases in T3 and retinol. Adult bald eagles showed no relationship between contaminants and thyroid hormones, which is consistent with other studies of long-lived birds, perhaps because adult birds have time to adjust to contaminant levels. Measurement of circulating thyroid hormones appears to be a more useful biomarker than retinols, given the more consistent response of T4 to PCBs here and reported in the literature. We conclude that current environmental exposures to PCBs in British Columbia and in southern California are associated with significant decreases in T4, suggesting a potential negative effect on the endocrine system of nestling bald eagles. Environ. Toxicol. Chem. 2010;29:1301- 1310. © 2010 SETAC. Source
O'Sullivan G.,TRIUM Environmental Solutions |
Min B.-J.,TRIUM Environmental Solutions |
Bilyk J.M.,TRIUM Environmental Solutions |
Ciezki R.,City of Calgary |
And 2 more authors.
Environmental Forensics | Year: 2010
A forensic geo-gas investigation within an urban environment has identified distinct compositional and stable-isotope characteristics related to various reference sources of methane gas by using analytical techniques such as geochemical screening, stable-carbon and stable-hydrogen isotope analysis, and radioactive carbon-isotope analysis. The results of the investigation concluded that the combination of a number of geochemical indicators produced a distinctive geo-gas fingerprint for samples from similar reference sites. © Taylor & Francis Group, LLC. Source