Evi Van den Steen

Brominated flame retardants and organochlorines in the European environment using great tit eggs as a biomonitoring tool

Large-scale studies are essential to assess the emission patterns and spatial distribution of organohalogenated pollutants (OHPs) in the environment. Bird eggs have several advantages compared to other environmental media which have previously been used to map the distribution of OHPs. In this study, large-scale geographical variation in the occurrence of OHPs, such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (OCPs), was investigated throughout Europe using eggs of a terrestrial residential passerine species, the great tit (Parus major). Great tit eggs from 22 sampling sites, involving urban, rural and remote areas, in 14 European countries were collected and analysed (5-8 eggs per sampling site). The environmentally most important congeners/compounds of the analysed pollutants were detectable in all sampling locations. For PCBs, PBDEs and OCPs, no clear geographical contamination pattern was found. Sum PCB levels ranged from 143 ng/g lipid weight (lw) to 3660 ng/g lw. As expected, PCB concentrations were significantly higher in the sampled urban compared to the remote locations. However, the urban locations did not show significantly higher concentrations compared to the rural locations. Sum PBDEs ranged from 4.0 ng/g lw to 136 ng/g lw. PBDEs were significantly higher in the urbanized sampling locations compared to the other locations. The significant, positive correlation between PCB and PBDE concentrations suggests similar spatial exposure and/or mechanisms of accumulation. Significantly higher levels of OCPs (sum OCPs ranging from 191 ng/g lw to 7830 ng/g lw) were detected in rural sampling locations. Contamination profiles of PCBs, PBDEs and OCPs differed also among the sampling locations, which may be due to local usage and contamination sources. The higher variance among sampling locations for the PCBs and OCPs, suggests that local contamination sources are more important for the PCBs and OCPs compared to the PBDEs. To our knowledge, this is the first study in which bird eggs were used as a monitoring tool for OHPs on such a large geographical scale.

An exposure study with polybrominated diphenyl ethers (PBDEs) in female European starlings (Sturnus vulgaris): Toxicokinetics and reproductive effects

We exposed female European starlings to a pentabromodiphenyl ether (Penta-BDE) mixture through subcutaneous implants, and examined levels and profiles of polybrominated diphenyl ethers (PBDEs) together with reproductive effects. Sum PBDE levels increased significantly in the serum of the exposed females from 218+/-43 to 23,400+/-2035 pg/ml. Sum PBDE concentrations in the eggs of the exposed group ranged from 130+/-12 to 220+/-37 ng/g wet weight (ww). The profile in serum after egg laying was very similar to that in eggs. There were no detectable levels of HO-PBDEs in both serum and eggs. Fewer females of the exposed group initiated egg laying compared to the control group, although the difference was not significant. In addition, egg weight and volume were significantly higher in the exposed group. These results suggest that, at the investigated exposure levels (150 microg sum PBDEs/bird), PBDEs may have a negative effect on reproductive performance.

The use of blue tit eggs as a biomonitoring tool for organohalogenated pollutants in the European environment

In the present study, large scale geographical variation in the occurrence of organohalogenated pollutants (OHPs) was investigated throughout Europe using eggs of a terrestrial resident passerine species, the blue tit (Cyanistes caeruleus). Blue tit eggs from 10 sampling locations, involving suburban, rural and remote areas, in 7 European countries were collected and analysed. Sum polychlorinated biphenyl (PCB) levels ranged from 150ng/g lipid weight (lw) to 2003ng/g lw. Sum polybrominated diphenyl ethers (PBDEs) ranged from 3.95ng/g lw to 114ng/g lw. As expected, PCB and PBDE concentrations were significantly higher in the sampled suburban locations compared to the rural and remote locations. Sum organochlorine pesticides (OCPs) ranged from 122ng/g lw to 775ng/g lw. OCP concentrations were, against the expectations, found to be lower in the rural sampling locations compared to the other locations. Contamination profiles of PCBs, PBDEs and OCPs differed also among the sampling locations, which may be due to local contamination sources. Finally, we compared the results of this study with previously reported OHP concentrations in the eggs of a closely related species, the great tit (Parus major), from the same sampling locations in Europe. We found no differences in concentrations between the species. In addition, we found a significant, positive correlation between the sum PCB concentrations in blue tit eggs and great tit eggs, suggesting similar exposure pathways, mechanisms of accumulation and maternal transfer of PCBs. In conclusion, our results suggest the usefulness of eggs from passerine birds as a biomonitoring tool for OHPs on a large geographical scale.

Endocrine disrupting haematological and biochemical effects of polybrominated diphenyl ethers in a terrestrial songbird, the European starling (Sturnus vulgaris)

We exposed female European starlings (Sturnus vulgaris) during a 6month period to environmentally relevant concentrations of a pentabromodiphenyl ether (Penta-BDE) mixture (about 1740μg/kg body weight) through subcutaneous implants, and examined endocrine disruptive, haematological and biochemical effects. To investigate endocrine disrupting effects of PBDEs, testosterone, estradiol and thyroid hormones (T(3) and T(4)) were measured in the plasma. We found no significant differences between the control and exposed groups for any of the hormones. However, 14days after implantation, T(3) concentrations tended to be lower in the exposed group compared to the control group. For albumin, our results suggest that short term exposure of PBDEs may result in a negative effect on albumin, while the opposite was observed on a longer term (6months after implantation). However, from the statistical analysis, effects on albumin disappeared when excluding females that laid eggs. These results demonstrate that observed effects during the breeding season should be interpreted carefully when the breeding status of females is unknown. There were no significant differences found between the control and exposed groups for the other biochemical parameters (total protein, uric acid, cholesterol, aspartate transaminase, total antioxidative capacity, high-density lipoproteins and creatine kinase) and haematological parameters (amount of red blood cells, haemoglobin concentration, haematocrit, mean corpuscular volume and mean corpuscular haemoglobin). All together, our results suggest that European starlings, similar to other passerine species, may be less sensitive to the effects of organohalogenated pollutants, such as PBDEs, than other bird species.

Kinetics of primary antibody responses to sheep red blood cells in birds: a literature review and new data from great tits and European starlings

Measuring the primary antibody immune response to an injection with sheep red blood cells (SRBC) is a routine application in poultry science. Recently, this technique is also becoming an increasingly popular tool to investigate humoral immunocompetence in free-living birds in studies of ecological immunology and immunotoxicology. However, an extensive search of the literature revealed that many of these studies have been measuring the primary immune response to SRBC without verifying first when maximum levels of antibodies are reached in the bird species under study. In addition, most studies assessed antibody titres to SRBC approximately 6 days after their inoculation assuming a similar pattern as found in poultry. We tested this assumption of a uniform pattern of kinetics of the primary humoral immune response to SRBC across bird species and investigated it in detail in two important model species, namely the great tit Parus major and the European starling Sturnus vulgaris . In general, the pattern was found to be the same in both passerine species and strongly resembled the pattern observed in chickens. Maximum antibody levels (the plateau phase) were reached on, respectively, day 5 and day 6 (with day of inoculation = day 0) of the immune response in the great tit and the starling and lasted for 3 days in both species. We found no effects of age, sex or time spent in captivity. Furthermore, our findings suggest that antibody levels to SRBC should not be obligatory assessed during the plateau phase of maximum antibody levels although it still remains most accurate to do so or at least shortly before or after it. Overall, we conclude that antibody levels have been reliably assessed in most avian studies using this technique.

Effects of laying order and experimentally increased egg production on organic pollutants in eggs of a terrestrial songbird species, the great tit (Parus major)

In this study, concentrations and profiles of organic pollutants were investigated in a passerine species with a large clutch size, the great tit (Parus major). In the first clutches, mean egg concentrations decreased significantly in relation to the laying order from 3025+/-416 ng/g lw to 2267+/-386 ng/g lw for sum PCBs and from 989+/-339 ng/g lw to 695+/-320 ng/g lw for sum DDTs. Sum PBDE concentrations also decreased in relation to the laying order from 68+/-10 ng/g lw to 53+/-11 ng/g lw, but not significantly. Although laying order effects were found, variation in concentrations within clutches was smaller than among clutches. To further investigate the impact of laying large numbers of eggs on levels and profiles of organic pollutants, initiation of replacement clutches was experimentally induced. Mean sum PCB and sum PBDE concentrations were significantly lower in eggs of replacement clutches compared to first clutches. In addition, first clutches had a higher contribution of the higher chlorinated and more persistent PCB congeners, CB 170, 180 and 183, and a lower contribution of CB 52, 95 and 149 compared to replacement clutches. Because of the differences in concentrations and profiles between the first and replacement clutches, the combined use of eggs from both the first and replacement clutches for monitoring purposes is not recommended. In conclusion, we suggest that, due to the larger variation among clutches compared to the variation within clutches, one randomly collected great tit egg from a first clutch is useful as a biomonitoring tool for organic pollutants. To our knowledge, this is the first study in which the impact of an experimentally increased clutch size on the levels and profiles of contaminants in eggs has been investigated.