Umbilical artery velocity waveforms before and after chorionic villus sampling

Because a vascular aetiology has been suggested for the limb and oromandibular defects described after chorionic villus sampling (CVS), to determine whether transabdominal (TA) CVS causes noticeable changes in umbilical artery velocity waveforms in first-trimester pregnancies, the pulsatility index (PI) of the umbilical artery was evaluated before and after TA-CVS in 175 pregnancies sampled between 10·0 and 13·0 weeks' gestation. In 139 uncomplicated pregnancies, the mean PI values (with 95 per cent confidence interval) were before TA-CVS 2·751 (2·692–2·809), after 10 min 2·723 (2·697–2·809), and after 1 h 2·781 (2·722–2·840). There were no significant changes in PI relative to the CVS procedure either in pregnancies with an abnormal result or in those ending in spontaneous abortion. Our data do not support any statistically significant change in umbilical artery PI relative to TA-CVS in first-trimester pregnancies. This procedure, despite its invasive character, does not appear to affect the feto-placental circulation.     

Public health assessment of hexachlorobenzene

Recently, hexachlorobenzene (HCB) was proposed for inclusion in the system of toxicity equivalency factors (TEFs) currently used for dioxin-like compounds. In this paper, we explore the practical implications of the proposition to the Agency for Toxic Substances and Disease Registry (ATSDR) programs by comparing respective health guidance values for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and HCB (expressed as total toxicity equivalents [TEQs]), reviewing possible interactions between HCB and dioxin-like chemicals, and by providing information on actual co-existence of HCB and dioxin-like chemicals at hazardous waste sites. We found a good correlation between the TEF-adjusted oral exposure guidance values for HCB and guidance values for TCDD. The combination of HCB and other dioxin-like compounds was not found in soil, air, or water media at hazardous waste sites. Based on this fact, it is not necessary to include HCB in the total TEQ count at hazardous waste sites at this time.     

Biotic and abiotic transformations of methyl tertiary butyl ether (MTBE)

Background Methyl tertiary butyl ether (MTBE) is a fuel additive which is used all over the world. In recent years it has often been found in groundwater, mainly in the USA, but also in Europe. Although MTBE seems to be a minor toxic, it affects the taste and odour of water at concentrations of < 30 μg/L. Although MTBE is often a recalcitrant compound, it is known that many ethers can be degraded by abiotic means. The aim of this study was to examine biotic and abiotic transformations of MTBE with respect to the particular conditions of a contaminated site (former refinery) in Leuna, Germany. Methods Groundwater samples from wells of a contaminated site were used for aerobic and anaerobic degradation experiments. The abiotic degradation experiment (hydrolysis) was conducted employing an ion-exchange resin and MTBE solutions in distilled water. MTBE, tertiary butyl formate (TBF) and tertiary butyl alcohol (TBA) were measured by a gas chromatograph with flame ionisation detector (FID). Aldehydes and organic acids were respectively analysed by a gas chromatograph with electron capture detector (ECD) and high-performance ion chromatography (HPIC). Results and Discussion Under aerobic conditions, MTBE was degraded in laboratory experiments. Only 4 of a total of 30 anaerobic experiments exhibited degradation, and the process was very slow. In no cases were metabolites detected, but a few degradation products (TBF, TBA and formic acid) were found on the site, possibly due to the lower temperatures in groundwater. The abiotic degradation of MTBE with an ion-exchange resin as a catalyst at pH 3.5 was much faster than hydrolysis in diluted hydrochloric acid (pH 1.0). Conclusion Although the aerobic degradation of MTBE in the environment seems to be possible, the specific conditions responsible are widely unknown. Successful aerobic degradation only seems to take place if there is a lack of other utilisable compounds. However, MTBE is often accompanied by other fuel compounds on contaminated sites and anaerobic conditions prevail. MTBE is often recalcitrant under anaerobic conditions, at least in the presence of other carbon sources. The abiotic hydrolysis of MTBE seems to be of secondary importance (on site), but it might be possible to enhance it with catalysts. Recommendation and Outlook MTBE only seems to be recalcitrant under particular conditions. In some cases, the degradation of MTBE on contaminated sites could be supported by oxygen. Enhanced hydrolysis could also be an alternative. - * The basis of this peer-reviewed paper is a presentation at the 9th FECS Conference on 'Chemistry and Environment', 29 August to 1 September 2004, Bordeaux, France.     

A comparison of five rapid direct toxicity assessment methods to determine toxicity of pollutants to activated sludge

Five rapid direct toxicity assessment methods were used in three European partner countries to determine the toxicity of single toxicants, mixed toxicants and real industrial wastes. The final aim was to protect microbial degradation of organic wastes in biological treatment processes and hence enhance the quality of treated effluents to be discharged to the environment. Nitrification inhibition, Respirometry, Adenosine triphosphate luminescence and Enzyme inhibition were tested utilising activated sludge as the testing matrix. The Vibrio fischeri toxicity test was used as a surrogate to compare the various microbial bioassays. The IC50 (toxicant concentration eliciting a 50% inhibitory effect) was determined for a number of pollutants including single toxicants Cd, Cr, Cu, Zn, 3,5-dichlorophenol, toluene and linear alkylbenzenesulphonate (LAS); a standard mixture of metals and LAS; a standard mixture of organics and LAS, and 16 industrial effluents. The V. fischeri bioassay was also chosen in order to assess quality control of toxicant preparation during testing in the different laboratories of the partner countries. Comparisons of sensitivity, cost of implementation, cost per test, relevance, and ease of use were made. The most sensitive bioassays were V. fischeri and Nitrification inhibition, however, this depended in the main on the pollutant and mixtures tested. It is recommended that during assessment of wastewater toxicity a suite of tests be used rather than reliance on one particular test.     

Genotype-specific responses of fluctuating asymmetry and of preadult survival to the effects of lead and temperature stress in Drosophila melanogaster

Although fluctuating asymmetry (FA) increases with exposure to certain types of environmental stressors such as temperature extremes, relatively little is known about the effects of interaction (e.g., synergism) between known sources of environmental stress on FA. Knowledge of such interaction effects, and of the magnitude of genotype-by-environment interaction, are of fundamental importance toward predicting the usefulness of FA as a bioindicator of environmental pollution. We tested for synergistic effects on FA between elevated temperature and exposure to lead, and examined FA responses simultaneously in four genetic strains of Drosophila melanogaster known to differ in their degree of developmental instability, and presumably in their buffering capacity. In the absence of heavy metal, bristle FA increased with temperature, but in the presence of lead, FA at high temperature (30 (degrees)C) was reduced to levels similar, or below, that at lower temperature (25 (degrees)C). This temperature by lead interaction was statistically significant, but paradoxical in that the disruptive effects of temperature appeared to be attenuated in the presence of the heavy metal. In no case was there a significant effect of lead on bristle FAs, despite documented assimilation of heavy metal by flies, and in no case was the genotype by environment interaction significant. Whereas lead treatment did not influence survival, survival was reduced at the high temperature, but significantly so only in one genetic strain (Oregon-R). There was no relationship between survival and FA across stress treatments within lines. Thus, any disproportionate stress-induced mortality in developmentally unstable classes (developmental selection) was unlikely to bias the FA results. Our results underscore the need for independent replication of significant findings before FA-based biomonitoring can be responsibly and effectively implemented. The results call for caution in using FA as a biomarker of stress, because stress factors may interact in complex and unpredictable ways, which could result in erroneous conclusions about real levels of stress present in field populations, under the unduly simplistic assumption that stress factors will act additively to increase FA.     

The cytotoxic effect of wastewater from the phosphoric gypsum depot on common oak (Quercus robur L.) and shallot (Allium cepa var. ascalonicum)

The effect of wastewater from a phosphoric gypsum depot on common oak, Quercus robur L., at cytogenetical level was studied. Allium-test was used as a control. The treatment of common oak seedlings with wastewater under laboratory conditions caused mitodepressive effect. Chromosome aberrations and mitotic irregularities were found. Cytogenetic analysis of common oak seedlings grown from acorns collected near the depot did not show changes in mitotic activity in comparison to control but the number of aberrations was higher than in control. In comparison to Alliumtest common oak was found to be more tolerant to wastewater from the phosphoric gypsum depot.     

Phenotypic plasticity in Scenedesmus incrassatulus (Chlorophyceae) in response to heavy metals stress

The microalgae genus Scenedesmus is commonly found in freshwater bodies, wastewater facilities and water polluted with heavy metals. Phenotypic plasticity in Scenedesmus has been documented in response to a wide variety of conditions; however, heavy metals have not been comprehensively documented as phenotypic plasticity inducers. In this study, we report the phenotypic plasticity of Scenedesmus incrassatulus (a non-spiny, four-cell coenobium forming species) in response to EC₅₀ value of copper, cadmium and hexavalent chromium. S. incrassatulus was grown in batch cultures in the presence of each metal. Chlorophyll-a content, cell size, parameters derived from the schematic energy-flux model for photosystem II, and morphotype expressions were recorded. Divalent cation metals induced unicellular forms, and hexavalent chromium produced out-of-shape coenobia corresponding to various stages of autospore formation. The changes induced by divalent metals were interpreted as phenotypic plasticity, because they were always associated to population doublings and were reversible when toxicant pressure was removed (only for Cu). Copper was the best inductor of unicellular forms and also affected significantly all the photosynthetic parameters measured. The developed morphotypes could confer ecological advantages to S. incrassatulus in metal stressed environments.     

Occurrence of polybrominated diphenylethers, polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls in coastal sediments from Spain

Fifteen sediment samples were analysed in order to determine their content of polybrominated diphenylethers (PBDEs), polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs). Samples were collected from several hot spots on the Spanish coast, such as the harbours of Almeria and Tarragona, and the mouths of the Besos and Llobregat rivers in Barcelona. A generic analytical procedure based on Soxhlet extraction followed by an automated cleanup system and gas chromatography-ion trap-mass spectrometry was employed for determining the toxic congeners of PCDDs and PCDFs, as well as dioxin-like PCBs. As regards PBDE determinations, a rapid method based on the use of selective pressurized liquid extraction followed by gas chromatography-negative ion chemical ionization-mass spectrometry was applied. Total toxicity equivalent (WHO-TEQ) values were calculated using the toxicity equivalent factors proposed by WHO for dioxin-like PCBs, PCDDs and PCDFs. WHO-TEQ values ranged from 0.3 to 75 pg/g dry weight (dw), with PCB contribution on the toxicity of the samples between 1 and 84%. Total PBDE levels ranged from 2.7 to 134 ng/g dw, with BDE-209 contribution on the total PBDE contamination between 50 and 99%.     

Effect of different radiotracer labelling techniques on radionuclide excretion from marine organisms

Experiments were designed to assess the effect of different techniques of radiotracer labelling on subsequent radioisotope excretion rates in marine crustaceans. A small amphipod (Gammarus locusta) that accumulated ⁶⁵Zn under a close approximation of natural conditions excreted the radiotracer during a 3-month period at a markedly different rate than those of comparable amphipods labelled with ⁶⁵Zn in the laboratory via different combinations of radioactive food and seawater. Shrimp (Lysmata seticauda) administered ⁶⁵Zn by three different methods in the laboratory displayed different excretion kinetics during the first 2 months of loss. The difference between excretion rates most likely was a reflection of the degree to which the various zinc pools within the shrimp had equilibrated with the radiotracer. During the next several months all ⁶⁵Zn loss rates were quite similar, probably indicating that radiotracer excretion was taking place from similar zinc pools within the shrimp. The importance of adequate radiotracer labelling techniques as well as proper design of subsequent excretion experiments, used to gain reliable information on flux rates of the corresponding stable metal, is discussed. It is concluded that laboratory radiotracer experiments which are intended to supply information on actual situations in the sea require careful design and execution.     

First in vitro use of the phenylphosphate carboxylase enzyme in supercritical CO2 for the selective carboxylation of phenol to 4-hydroxybenzoic acid

A new biotechnological synthetic approach to 4-hydroxybenzoic acid is reported. Thauera aromatica cells produce the phenylphosphate carboxylase enzyme that selectively carboxylates phenylphosphate in the para position, without any formation of the ortho isomer. Here we show that the enzyme also works in supercritical carbon dioxide, opening a new technological solution to the recovery of the products that is a key problem when aqueous media are used. The enzyme shows an activity comparable with that shown under CO₂ pressure in aqueous media and does not require the presence of NaHCO₃.