Geographical Distribution (2000) and Temporal Trends (1981−2000) of Brominated Diphenyl Ethers in Great Lakes Herring Gull Eggs

Geographical distribution of brominated diphenyl ether (BDE) flame retardants in the North American Great Lakes ecosystem in 2000 was determined by analysis of herring gull eggs (13 egg pools) from a network of 15 monitoring colonies scattered throughout the lakes and connecting channels. ΣBDEs were found at concentrations ranging from 192 to 1400 μg/kg, mean of 662 ± 368 μg/kg (wet weight of egg contents). Highest concentrations were found in northern Lake Michigan and Toronto harbor (1000-1400 μg/ kg) and lowest in Lake Huron and Lake Erie (192-340 μg/ kg). The distribution suggested that input from large urban/ industrial areas through air or water emissions contributes local contamination to the herring gull food web in addition to background levels from regional/global transport. The congener composition was similar among sampling sites. Major congeners were BDE-47 (43%), BDE-99 (26%), BDE-100 (13%) BDE-153 (11%), BDE-154 (4%), BDE-183 (2%) and BDE-28 (1%). Temporal trends of BDE contamination, 1981-2000, were established by analysis of archived herring gull eggs (10 egg pools) from colonies in northern Lake Michigan, Saginaw Bay, Lake Huron and eastern Lake Ontario. BDE-47, -99 and -100, and BDE-153, -154 and -183 concentrations were grouped separately for analysis because these two groups had different trends and are primarily associated with the Penta BDE and Octa BDE flame retardant formulations, respectively. ΣBDE 47,99,100 concentrations were 5-12 μg/kg (wet weight) in 1981-1983 and then increased exponentially (p < 0.00001) at all three sites to 400-1100 μg/kg over the next 17 years. Doubling times were 2.6 years in Lake Michigan, 3.1 years in Lake Huron and 2.8 years in Lake Ontario. ΣBDE 154,153,183 concentrations generally increased but varied in an erratic fashion among sites and decreased as a fraction of ΣBDE over time. Concentrations of ΣBDE 154,153,183 were 100-200 μg/kg in eggs from all three colonies in 2000. Therefore, most of the dramatic increases in ΣBDE concentrations observed over the past 20 years in the Great Lakes aquatic ecosystem seem to be connected with the Penta BDE formulation, which is mainly used as a flame retardant in polyurethane foam in North America. If present rates of change continue, concentrations of ΣBDEs will equal or surpass those of ΣPCBs in Great Lakes herring gull eggs in 10-15 years.