title: In vitro biotransformation of decabromodiphenyl ether (BDE-209) and Dechlorane Plus flame retardants: a case study of ring-billed gull breeding in a pollution hotspot in the St. Lawrence River, Canada.
abstract: Decabromodiphenyl ether (deca-BDE) mixture (~97% of BDE-209) is now facing usage restrictions worldwide, which is leading to increased utilization of a series of alternative, replacement flame retardant (FR) products. Among these, Dechlorane Plus (DP) is receiving growing attention as this FR is increasingly being detected in wildlife samples, including birds from North America, Europe and Asia. Recent survey conducted in a known FR hotspot in the St. Lawrence River basin near Montreal (QC, Canada) revealed unexpectedly high detection frequencies and concentrations of BDE-209 and DP isomers (syn- and anti-DP) in the liver of breeding ring-billed gulls (Larus delawarensis) (RBGUs). Despite the global distribution of these current-use FRs, there is to our knowledge no study that has addressed the in vitro biotransformation of BDE-209 and DP isomers in birds. This study aimed at understanding the in vitro metabolism of BDE-209 and syn- and anti-DP using liver microsomes of Montreal-breeding RBGUs. Although BDE-15 (positive assay control) was consistently and positively depleted over the 90-min time frame of the in vitro assay, no depletion was observed for BDE-209 and DP isomers. These results suggest that CYP isoenzyme-mediated reductive dehalogenation of BDE-209 and DP is not likely to be a substantial metabolic pathway in RBGUs. However, investigations on deiodinases (expression, activity) should be considered in future studies as these enzymes have been suggested to be involved in the sequential debromination of BDE-209 in fish and human studies. High levels of BDE-209 determined in liver of RBGUs that strongly correlated with those of known or suggested BDE-209 debromination products (hepta- through nona-BDEs) may thus be indicative of concomitant dietary (e.g., fish consumption) and environmental exposure in the greater Montreal area, combined with poor or lack of metabolic capability toward these FRs.
authors.affiliation: Centre de recherche en toxicologie de l'environnement (TOXEN), Département des sciences biologiques, Université du Québec à Montréal, C.P. 8888, Succursale Centre-ville, Montreal, QC, Canada H3C 3P8.
authors.forename: Bernice
authors.initials: B
authors.lastname: Chabot-Giguère
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Letcher
authors.forename: Jonathan
authors.initials: J
authors.lastname: Verreault
mesh_terms: D000818:Animals; D001711:Biotransformation; D001947:Breeding; D002170:Canada; D046091:Charadriiformes / Q000378:metabolism*; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000378:metabolism*; D004787:Environmental Pollution / Q000706:statistics & numerical data; D005411:Flame Retardants / Q000378:metabolism*; D055768:Halogenated Diphenyl Ethers / Q000378:metabolism*; D006843:Hydrocarbons, Chlorinated / Q000378:metabolism*; D011083:Polycyclic Compounds / Q000378:metabolism*; D045483:Rivers / Q000737:chemistry
chemical_list: D004785:Environmental Pollutants; D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D006843:Hydrocarbons, Chlorinated; D011083:Polycyclic Compounds; C526360:dechlorane plus; C010902:decabromobiphenyl ether