DDT und Metaboliten in Sedimenten Berliner Gewässer

Sediment samples from rivers and lakes of Berlin (Germany) were analysed for their contamination with organic compounds by means of qualitative and quantitative GC/MS analysis. The principal compounds detected were PAH, organotin derivates, several classes of chlorinated, brominated and mixed halogenated compounds and some of their related metabolites. The DDT metabolites DDD, DDE, DDCN, DDMU and DDMS were the most abundant compounds of halogenated pesticides in a wide range of samples. The main metabolite determined was p,p′-DDD, with concentrations up to 1230 μg/kg dw. The parent DDT compound was detected in only a few samples. The acute cytotoxicity of selected DDT-metabolites was determined with the permanent cell line RTG-2 from the gonads of the rainbow trout (Oncorhynchus mykiss). The results indicate a high cytotoxic potential of these metabolites. The oestrogenic potential was determined by the Dot-Blot/RNase-Protection-Assay an the order from o,p′-DDT>p,p′-DDMS>p,p′-DDMU≥p,p′-DDCN. Risk assessments based on chemical analysis of DDT, DDD and DDE alone is not able to estimate the real toxic potential of DDT and its metabolites. The development of a method for bioassay directed assessment seems to be an effective strategy to solve this problem. Especially scarce or not available data of combinatory effects, differences between different trophic levels and their availability to biota and low knowledge about the metabolism in situ as well as the enantioselective characteristics of most chiral DDT metabolites warrant future analyses.     

Alternative Non-market Value-Elicitation Methods: Are the Underlying Preferences the Same?

We advocate a more formal structural approach for comparing WTP for non-market or pre-test-market goods conveyed by fundamentally different preference elicitation mechanisms. Seven independent samples of respondents were asked to value the identical good. Elicitation methods include one actual purchase and six widely used hypothetical choice formats. Using a common underlying indirect utility function (and stochastic structure) allows data for different elicitation methods to be used independently, compared pair-wise (as in much of the earlier literature) or pooled across all samples in one unified model with heteroscedasticity across elicitation methods. Our differences in estimated WTP for the individual models are typical of earlier findings. However, pooled-data models that allow for heteroscedasticity reveal that while there are substantial differences in the amount of noise in the different samples, a common underlying systematic component of the preference structure cannot be rejected for at least four (and possibly five) of these seven elicitation methods.     

Identification of a phytotoxic photo-transformation product of diclofenac using effect-directed analysis

The pharmaceutical diclofenac (DCF) is released in considerably high amounts to the aquatic environment. Photo-transformation of DCF was reported as the main degradation pathway in surface waters and was found to produce metabolites with enhanced toxicity to the green algae Scenedesmus vacuolatus. We identified and subsequently confirmed 2-[2-(chlorophenyl)amino]benzaldehyde (CPAB) as a transformation product with enhanced toxicity using effect-directed analysis. The EC₅₀ of CPAB (4.8 mg/L) was a factor of 10 lower than that for DCF (48.1 mg/L), due to the higher hydrophobicity of CPAB (log K_ow = 3.62) compared with DCF (log D_ow = 2.04) at pH 7.0.     

Cardiac defects in chromosomally abnormal human embryos of 10–14 weeks' gestation

Cardiac defects were studied in five chromosomally abnormal embryos of 10–14 weeks' gestation by free-hand microdissection of hearts measuring 2·5–6 mm in diameter. The type of cardiac malformation alone or in association with other anomalies helped to confirm the chromosome diagnosis established prenatally by chorionic villus sampling or after spontaneous abortion. It was suggestive of a chromosomal disorder in one case in which cytogenetic investigation had failed.     

Ökotoxikologische Untersuchung von Sedimenten und Schwebstoffen

The potential risk of ground-water contamination through the infiltration of contaminants originating from suspended matter and sediments deposited within flood retention areas in the Upper Rhine valley, as well as subsequent problems for drinking water production, were analyzed by means of the bacterial dehydrogenase activity (DHA; sediment contact test) assay with Arthrobacter globiformis and in a prolonged embryo toxicity assay using zebrafish (Danio rerio). Since the direct uptake of contaminants from particle-bound sources has usually been assumed to play only a minor role in bioaccumulation, the availability of organic extracts to biota has generally been regarded as being overestimated. In order to confirm or discard this hypothesis, organic (acetone) extracts of recently suspended, freeze-dried matter, as well as freeze-dried sediments collected from Rhine flood plains (i.e. soil samples) were compared to corresponding native samples in order to screen for the relative availability of particle-bound contaminants. Whereas a significantly higher ecotoxicological burden was observed for some native soil samples, organic extracts of suspended matter proved to be more toxic than corresponding native samples when compared to organic extracts using each test system. With respect to organic extracts, the suspended matter samples were more toxic than soil samples taken from a rarely flooded site. In contrast to the native samples, the rarely flooded soils revealed a higher toxicity than suspended matter. Therefore, organic extracts did not necessarily overestimate the toxicity of soil and suspended matter samples. Moreover, considerable toxicity of particle-bound contaminants to both bacteria and fish embryos, even in native samples, corroborate the hypothesis that particle-bound contaminants may be more readily available than is generally assumed.     

Chromosomal mosaicism confined to chorionic tissue

Chorionic villus samples from two healthy pregnant females were obtained for first trimester fetal diagnosis. The karyotypes were 46, XX/47, XX, +3 and 46, XX/47, XX, +15, respectively. In both cases fibroblast cultures after termination of pregnancy were shown to have normal karyotypes.