Trends of persistent organic pollutants in American eel (Anguilla rostrata) from eastern Lake Ontario, Canada, and their potential effects on recruitment.

This study reports the history of contamination of American eels (Anguilla rostrata) from eastern Lake Ontario (LO) by persistent organic pollutants (POPs). Three groups of 10 large female eels captured in eastern LO in each of 1988, 1998, and 2008 were analysed for polychlorinated dibenzo-p-dioxins and furans, polychlorinated biphenyls, several organochlorine pesticides, and polybrominated diphenyl ethers. Mean concentrations were up to 3-fold lower in 2008 compared to previous years. When combined with the results of previous studies, these data show that concentrations of POPs in American eels have declined exponentially since the early 1980s by an average of 9.1±1.9% per year. Toxic equivalent (TEQ) concentrations of dioxin-like compounds (DLCs) were calculated from fish toxic equivalency factors. Assuming an efficient transfer of DLCs to their eggs, egg TEQs prior to 2000 exceeded the threshold for chronic toxicity to embryos of European eels (Anguilla anguilla) and lake trout (Salvelinus namaycush) (4-5 pg/g ww of TEQ). These results suggest that embryotoxicity of maternally-derived DLCs from LO eels, historically a major contributor to the spawning stock of American eels, could have impaired the reproductive and recruitment success of the species.

A twenty-one year temporal trend of persistent organic pollutants in St. Lawrence Estuary beluga, Canada.

Persistent organic pollutants (POPs) were measured in blubber from 144 stranded adult belugas (Delphinapterus leucas) found on the shores of the St. Lawrence Estuary (SLE) between 1987 and 2007. Temporal trends of POP concentrations (ln transformed) in beluga were described by three models, zero slope (ZS), linear (L) and two-segment piecewise (PW). Often two but sometimes all three models were equivalent in describing temporal trends based on Akaike's Information Criterion for small sample sizes. Over this 21-year time period, concentrations of most legacy POPs, including PCBs, DDTs and HCHs, exhibited relatively weak (≤11% per year) but significant decreasing trends in beluga. For PBDEs, temporal trends were best described by a PW model, characterizing a rapid increase until 1997-1998 followed by a slower increase for males and a steady-state for females. Potential cofactors such as blubber lipid content and carcass state of preservation did not show any significant temporal trends over the time period considered. Nitrogen stable isotope ratios (δ(15)N) in beluga liver, a proxy of trophic level, could not be associated to any effect on temporal trends of POP concentrations in beluga. Several POPs exhibited significant relationships with age of beluga and data were age-adjusted. Temporal trends of POP concentrations adjusted for age of beluga were reassessed but results were essentially identical as those obtained with the original POP data. Overall, POP temporal trends observed in SLE beluga are consistent with changes expected from regulations and restrictions in the use of these compounds in developed countries.

Spatial trends of organochlorinated pesticides, polychlorinated biphenyls, and polybrominated diphenyl ethers in Atlantic Anguillid eels.

The bioaccumulation of lipophilic contaminants such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs) can result in a reduction in fitness and spawner quality in eels and may be a factor in Anguillid sp. population declines. Contaminant concentrations in eels have been studied extensively in Europe, but data for American eels are severely lacking. Concentrations of PCBs, OCPs, and PBDEs were determined in American eel from eastern Canada and New York, USA, along with European eel from Belgium. Principal component analysis revealed that eels captured in the St. Lawrence estuary were a mixture of upstream migrants from the St. Lawrence River watershed, and fish captured in local tributaries. Contaminant concentrations were dependent on origin, related to the local environment, and were lower than historic values. In Canada, concentrations of OCPs and PCBs in eel tissues were below the Canadian human consumption guidelines for contaminants in fish, indicating that the current risk to consumers is low. However, concentrations of PCBs, total DDT, and mirex in eels from L. Ontario and the upper St. Lawrence R. were above Great Lakes guidelines for the protection of piscivorous predators. Concentrations of penta-BDE homologs exceeded the Canadian guideline for environmental quality in over half of the eels in this study, but concentrations of the other homolog groups were below the guideline.

Temporal trends (1987-2002) of persistent, bioaccumulative and toxic (PBT) chemicals in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary, Canada.

Temporal trends of persistent, bioaccumulative and toxic (PBT) chemicals were examined in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary (SLE), Canada. Blubber samples of 86 adult belugas were collected from animals stranded on the shore of the SLE between 1987 and 2002 and analyzed for several regulated PBTs, including polychlorinated biphenyls (PCBs), p,p'dichlorodiphenyltrichloroethane (DDT) and its metabolites, chlordane (CHL) and related compounds, hexachlorocyclohexane (HCH) isomers, hexachlorobenzene (HCB) and Mirex. In addition, time trends of tris(4-chlorophenyl)methane (TCPMe) and tris(4-chlorophenyl)methanol (TCPMOH), two compounds that may origin from DDT formulations, were also examined. Concentrations of most of the PBTs examined had exponentially decreased by at least a factor of two (half-life time (t(1/2))<15 years) in beluga between 1987 and 2002 while no increasing trends were observed for any of the PBTs measured. The decreasing trends of PBT concentrations in SLE beluga may be due to a decline in contamination of its diet following North American and international regulations on the use and production of these compounds or by a change in its diet itself or by a combination of both. Some PBTs did not exhibit any significant trends in beluga possibly because the most intense elimination phase subsequent to legislative regulations occurred prior to the 1987-2002 time period. Other chemicals, such gamma-HCH, did not significantly decrease likely because they are still currently used in some restricted applications. Conversely, alpha-HCH showed a significant decreasing trend indicating that SigmaHCHs is not representative of all HCHs. Both TCPMe and TCPMOH exhibited no trends in beluga during the time period examined. The metabolic capacity of SLE beluga has apparently accelerated the depletion of at least one PBT, namely CB-28/31. A significant relationship between the half-life of PBTs in beluga and log Kow was observed for most of the chemicals examined. Several factors are expected to have influenced the temporal changes of PBT concentrations in beluga which limit the usefulness of this species as a bioindicator of changes in PBT contamination in the SLE ecosystem.

Effects of deBDE and PCB-126 on hepatic concentrations of PBDEs and methoxy-PBDEs in Atlantic tomcod.

The biotransformation of high bromosubstituted polybrominated diphenyl ethers (PBDEs) congeners contained in a commercial deca mixture (DeBDE) is of environmental concern because it might lead to the increase of toxic low brominated PBDEs in biota. A few studies have reported that freshwater fish dietary exposed to DeBDE or its main constituent, decabrominated PBDE congener (BDE-209), had their tissues enriched with PBDEs not initially present in fish or feed. In the present study, Atlantic tomcod (Microgadus tomcod) were intraperitoneally (IP) injected with DeBDE to assess hepatic concentration changes of PBDEs and methoxy polybrominated diphenyl ethers (MeO-PBDEs) in a marine fish species. Tomcod were also IP injected with polychlorinated biphenyl (PCB)-126 to evaluate the impact of cytochrome P4501A (CYP1A) induction on the biotransformation of injected PBDEs contained in DeBDE and PBDEs initially present in fish. Besides BDE-209, concentrations of BDE-203 and three other unidentified octabrominated PBDEs and the nonabrominated PBDEs (BDE-206, -207, and -208) were enriched in the liver of fish injected with DeBDE. All these PBDE congeners, essentially absent in control fish, were identified as impurities in DeBDE, and, thus, their presence could not be attributed exclusivelyto biotransformation. Despite a 4.3times increase of EROD activity in the liver of tomcod injected with both PCB-126 and DeBDE, compared to DeBDE alone, no further increases of PBDE hepatic concentrations were observed. However, depleted concentrations of BDE-17 (x 1.5) and 6-MeO-BDE-47 (x 1.4) were found in fish IP injected with DeBDE compared to control fish, likely due to activated hepatic metabolic enzymes other than CYP1A. Fish injected with PCB-126 showed an even more significant depletion of BDE-17 hepatic concentrations (x 3.5) than the one associated with the DeBDE treatment and a significantly lower proportion of fish with quantifiable concentrations of BDE-203. Thus, CYP1A inducers can promote the biotransformation of PBDEs in fish liver. This study shows that exposure of fish to DeBDE is expected to result in the enrichment of high brominated PBDEs in fish liver and that metabolic activities in fish can affect their PBDE bioaccumulation pattern and possibly the toxicity of PBDEs to fish.

Levels and temporal trends (1988-1999) of polybrominated diphenyl ethers in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary, Canada.

Polybrominated diphenyl ethers (PBDEs) were determined in blubber samples of 54 stranded adult beluga whales (Delphinapterus leucas) collected between 1988 and 1999 in the St. Lawrence Estuary (SLE), Quebec, Canada. Summed concentrations of 10 PBDE congeners (sigmaPBDEs) measured in beluga samples varied between 20 and almost 1000 ng/g wet weight. According to the PBDE concentrations in marine mammals reported in the scientific literature, SLE belugas appear to be relatively lightly contaminated. Only a few predominant congeners (namely, PBDE-47, -99, and -100) represent on average more than 75% of sigmaPBDEs in SLE belugas. The accumulation of sigmaPBDEs in both male and female belugas showed significant exponential increase throughout the 1988-1999 time period. The time necessary for beluga to double their blubber concentration of the most prevalent PBDE congeners was no longer than 3 years. The PBDE temporal changes reported in this study are generally faster but in agreement with the trend observed in other organisms collected in Canada, such as lake trout (Salvelinus namaycush) from the Great Lakes, ringed seal (Phoca hispida), and beluga whale from the Canadian Arctic. Some changes in the pattern of PBDEs in belugas were also observed during the time period investigated. The recent and important increase of PBDE levels in SLE belugas could explain the unexpected lack of statistical difference in PBDE contamination between males and females. This suggests that to date PBDEs tend to be accumulated by both male and female belugas, masking the elimination of PBDEs by females through post-natal transfer to their offspring. This study confirms that the growing use of PBDEs as flame retardants has resulted in rising contamination of Canadian aquatic environments. Additional studies are needed to assess the toxicological implications of the PBDE tissue levels found in SLE belugas.

Analysis of six relevant toxaphene congeners in biological samples using ion trap MS/MS.

The quantification of six polychlorinated bornanes (CHBs) was studied using ion trap MS/MS. The significance of the selection of parent ions (Ip) and daughter ions (Id) on the detection of these toxaphene congeners was assessed in standard solution and biological samples. Our results indicate that different Ip and Id, selected at either low or high mass-to-charge (m/z) ratios, influence drastically the response factor of the CHBs and the chemical noise observed. For the octachlorinated toxaphene congeners (Parlar-26 (P-26), Parlar-40/41 (P-40/41), Parlar-44 (P-44)), the detection performance of the ion trap MS/MS is similar whether Ip and Id were chosen at low or high m/z ratios. However, the selection of Ip and Id at high m/z ratios clearly enhances the detection of the nonachlorinated toxaphene congeners (Parlar-50 (P-50), Parlar-62 (P-62)). The improved method, which selects Ip and Id at low m/z ratios for P-26, P-40/41 and P-44 and at high m/z ratios for P-50 and P-62, permitted to obtain low detection limits as well as repeatable and accurate results.