Polycyclic aromatic hydrocarbon (PAH) contamination of surface sediments and oysters from the inter-tidal areas of Dar es Salaam, Tanzania

Surface sediment and oyster samples from the inter-tidal areas of Dar es Salaam were analyzed for 23 polycyclic aromatic hydrocarbons (PAHs) including the 16 compounds prioritized by US-EPA using GC/MS. The total concentration of PAHs in the sediment ranged from 78 to 25,000 ng/g dry weight, while oyster concentrations ranged from 170 to 650 ng/g dry weight. Hazards due to sediment contamination were assessed using Equilibrium Partitioning Sediment Benchmarks and Threshold Effect Levels. Diagnostic indices and principle component analysis were used to identify possible sources. Interestingly, no correlation between sediment and oyster concentrations at the same sites was found. This is supported by completely different contamination patterns, suggesting different sources for both matrices. Hazard assessment revealed possible effects at six out of eight sites on the benthic communities and oyster populations. The contribution of PAH intake via oyster consumption to carcinogenic risks in humans seems to be low.     

Reproduction and survival of tawny owls in relation to persistent organic pollutants

The potential effects of organochlorines (OCs) and brominated flame retardants on reproduction and survival were studied in tawny owls (Strix aluco) in Central Norway over a period of 19 years (1986-2004). Concentrations of 14 OCs and five polybrominated diphenyl ethers (PBDEs) were measured in eggs (n=104), and Principal Component Analysis was used to produce composite measurements of pollutants; i.e. PC1 and PC2, which accounted for 85% of the variation in contaminant concentrations. There was no evidence for adverse associations between pollutants (PC scores) and life-history traits such as clutch size, probability of producing fledglings and survival, when controlling for potentially confounding variables. Moreover, there was no evidence for interactions between pollutants and vole abundance suggesting no synergistic effects of food stress and pollutants on these life-history traits. There was, however, some evidence for a non-linear negative association between p,p'-DDE (1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene) and eggshell thickness. This suggests that the concentrations of pollutants in this ecosystem were too low to affect reproduction and survival in an owl predominantly consuming prey at low trophic levels, but may be sufficient to cause eggshell thinning at the highest concentrations.     

Occurrence of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Lake Maggiore (Italy and Switzerland)

Samples of air (gas and particulate phases), bulk deposition, aquatic settling material and sediments were collected in Lake Maggiore (LM) in order to determine their content of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). Air (gas and particulate phases) concentrations were 0.5 pg m(-3), 80 pg m(-3), 13 pg m(-3) and 106 pg m(-3) for SigmaPCDD/Fs, SigmaPCBs, Sigma dioxin-like PCBs (DL-PCBs) and SigmaPBDEs, respectively. Deposition fluxes ranged from 0.7 ng m(-2) d(-1) for SigmaPCDD/Fs to 32 ng m(-2) d(-1) for SigmaPCBs. Aquatic settling material presented concentrations of 0.4 ng g(-1) dry weight (dw) for SigmaPCDD/Fs, 13 ng g(-1) dw for SigmaPCB, 3.4 ng g(-1) dw for SigmaDL-PCBs and 5.7 ng g(-1) dw for SigmaPBDEs. Mean sediment concentrations were 0.4 ng g(-1) dw for SigmaPCDD/Fs, 11 ng g(-1) dw for SigmaPCB, 3 ng g(-1) dw for SigmaDL-PCBs and 5.1 ng g(-1) dw for SigmaPBDEs. Similar PCDD/F and DL-PCB congener patterns in all the environmental compartments of LM point to an important, if not dominant, contribution of atmospheric deposition as source of these pollutants into LM. In contrast, PBDE congener distribution was not similar in the different environmental compartments. BDE 47 dominated air and settling material, while BDE 209 was the predominant congener in the bulk atmospheric deposition. Moreover, sediments showed two distinct PBDE congener profiles. Lower PBDE concentrated sediments were dominated by congeners 47 and 99, while BDE 209 dominated in higher PBDE concentrated samples. This suggests the influence of local sources as well as atmospheric input of PBDEs into LM.     

Prinzip und Anwendung des Radioimmunoassays

Radioimmunologic assay techniques are superior to most analytical procedures with regard to sensitivity, precision, general applicability, and experimental simplicity. Both for diagnosis and for monitoring of therapy this method has greatly advanced our understanding of endocrine physiology. Besides its use in clinical chemistry, radioimmunoassay is also employed in pharmacology, toxicology, and in pharmacokinetics of new drugs.