This paper is highly cited because it presents a number of novel findings relating to the environmental behavior of polybrominated diphenyl ethers (PBDEs). Our study was the first to show that PBDE concentrations have been increasing exponentially in the Arctic over the past 20 years, since these chemicals began to be used in consumer products. Our data clearly show the temporal trends of these compounds in the blubber of Arctic ringed seals and they also suggest that: a) PBDEs are atmospherically transported into this polar region; b) they move through the food-chain and they bioaccumulate in high trophic level organisms and c) that if they continue to accumulate at the present rates they will soon become the prevalent organohalogen contaminant in the Arctic. Our work also puts into perspective the concentrations of PBDEs relative to those of other toxic chemicals such as dioxins, furans, and PCBs measured in the same ringed seal samples. The patterns of PBDE congeners detected in the Arctic samples were also unique and very different from those detected in organisms living near direct sources of PBDEs.

There is an increasing interest and concern worldwide on the impact of PBDEs on human health, wildlife, and the environment. Our study is novel from the perspective that it provides new evidence on the environmental behavior of these compounds. The comprehensive, highly sensitive, and specific analytical methods we used for our measurements not only allowed us to detect these compounds in the Arctic, but we were also able to establish PBDE congener patterns in the ringed seal samples and compare with those of the PBDE commercial mixtures and with PBDE patterns found in organisms living near sources. It is my hope that our findings will be useful to fellow scientists and policy makers. Fellow scientists can use our data to develop models on the fate and the transport mechanisms of these chemicals in the environment, and policy makers can use the findings of this study as additional evidence to make decisions on the regulation of these chemicals.

  Could you summarize the significance of your paper in layman's terms?  

In this article we have shown that the PBDE chemicals, which are used as flame retardants in a variety of consumer products, are being atmospherically transported and are contaminating the Arctic at an unprecedented rate. In this study we have used a highly powerful analytical method to measure the concentrations and the patterns of PBDEs in a very unique set of ringed seal blubber samples from the Canadian Arctic. The data obtained allowed us to establish, for the first time, the temporal trends of these compounds in this remote polar region. We found the PBDE concentrations measured in the blubber of ringed seals (the most common seal in the Arctic) to have increased 10 fold since 1981 with a doubling rate of 4 to 5 years. Using these data we were able to predict that if these rates of accumulation continue PBDEs could soon surpass the PCBs—another persistent family of toxic chemicals that are know to accumulate through the food-chain—as the major class of organohalogen contaminant in the Arctic environment. At present, PBDE concentrations in the blubber of ringed seals were found to be 50 times lower than some of the PCBs and approximately 500 times higher than the dioxins and furans. Female ringed seals had lower levels of PBDEs than their male counterparts, which suggests that they pass these lipophilic contaminants to their offspring via lactation.

The specificity and sensitivity of the analytical approach we used permitted the elucidation of PBDE congener patterns to be established in all the samples we analyzed. We were able to identify that the PBDE congener profiles in arctic male ringed seals differed significantly from other marine mammals and aquatic organisms living near urban and industrial sites in western Canada. This is a unique and novel finding in its own right, as it can be used to model the transport of these contaminants into the Arctic.

Approximately five years ago in collaboration with other scientists from the Canadian government we started examining the occurrence of these compounds in environmental samples via a project funded by the Department of Fisheries and Oceans Canada (DFO). At the time, there were no data available describing the environmental behaviour and impact of these compounds in North America. This was one of the first studies on this continent and very early in our work we realized that these compounds were present, in variable concentrations, in every environmental sample we examined. Our curiosity then impelled us to study the impact of these chemicals in the Arctic.

A few years back I was fortunate enough to have collaborated with Drs. Richard Addison and Tom Smith from the DFO, who had done pioneering work on contaminants in the Canadian Arctic. I was aware that they possessed a well-preserved and very unique sample set of ringed seal blubber that dated back to early ‘70s. These colleagues provided me with representative samples that allowed us via this project to show very clearly that PBDEs are atmospherically transported to the Arctic and that their concentrations have been increasing exponentially over the past 20 years in this polar region. The oldest samples we analyzed for this project were collected just a few years after PBDEs were introduced into consumer products in North America and Europe.