Pure non-dioxin-like PCB congeners suppress induction of AhR-dependent endpoints in rat liver cells

The relative potencies of non-ortho-substituted coplanar polychlorinated biphenyl (PCB) congeners to activate the aryl hydrocarbon receptor (AhR) and to cause the AhR-dependent toxic events are essential for their risk assessment. Since some studies suggested that abundant non-dioxin-like PCB congeners (NDL-PCBs) may alter the AhR activation by PCB mixtures and possibly cause non-additive effects, we evaluated potential suppressive effects of NDL-PCBs on AhR activation, using a series of 24 highly purified NDL-PCBs. We investigated their impact on the model AhR agonist-induced luciferase reporter gene expression in rat hepatoma cells and on induction of CYP1A1/1B1 mRNAs and deregulation of AhR-dependent cell proliferation in rat liver epithelial cells. PCBs 128, 138, and 170 significantly suppressed AhR activation (with IC₅₀ values from 1.4 to 5.6 μM), followed by PCBs 28, 47, 52, and 180; additionally, PCBs 122, 153, and 168 showed low but still significant potency to reduce luciferase activity. Detection of CYP1A1 mRNA levels in liver epithelial cells largely confirmed these results for the most abundant NDL-PCBs, whereas the other AhR-dependent events (CYP1B1 mRNA expression, induction of cell proliferation in confluent cells) were less sensitive to NDL-PCBs, thus indicating a more complex regulation of these endpoints. The present data suggest that some NDL-PCBs could modulate overall dioxin-like effects in complex mixtures.     

The environmental state at sea

Seas and oceans are confronted with a plethora of environmental problems, caused by land-based activities (agriculture, industries, and ports) and by maritime activities (such as shipping, fishing, oil and gas drilling, tourism, and navigational dredging). Environmental problems at sea challenge the efficacy of state sovereignty. Who is responsible, accountable, and regulates environmental and spatial problems at the level of regional seas, and what is the role of states in these processes of governance? In the regional seas and on the high seas, the environmental state is challenged by two developments: states become players at different levels, and states are confronted with the activities of big market players where they have no or little jurisdiction. The different forms of the environmental state in Europe’s regional seas and in the Arctic Ocean are examined.     

Qualitative structure residue relationship analysis in the determination of the maximum residue limit of veterinary drugs

Aim of the present study was an attempt to find a correlation between physicochemical structure of veterinary drugs and the maximum residue limit (MRL) for muscle tissue of food producing animals. Direct correlation and analysis in quintile groups for 52 physicochemical parameters were performed. An internal validation using leave-one-out cross-validation was performed. In the quintile groups, there were 11 arithmetic expressions created for the limited group of individual parameters (13 from 52 analyzed), which showed a significant linear or quadratic correlation between the number of quintile group and the mean value of MRL within the quintile. The results obtained suggest that there is no direct correlation between individual physicochemical parameters and MRL value in muscle tissue; however, such correlation can be determined for arithmetic expressions created on the basis of several physicochemical parameters, using quintile group analysis.     

Brominated flame retardants and other organochlorine pollutants in human adipose tissue samples from the Czech Republic

Brominated flame retardants (BFRs) represented by polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) together with major persistent organochlorine pollutants, polychlorinated biphenyls (PCBs) and selected organochlorine pesticides (OCPs), were determined in adipose tissue samples (n=98) obtained by liposuction of Czech subjects. Compared to other organochlorine pollutants (mostly PCBs and DDTs), levels of PBDE were lower by 2 orders of magnitude ranging from 0.2 to 54.3 ng/g lipid weight. PBDE congeners No. 47, 99, 153 and 183 were the most abundant constituting up to 90% of these pollutants in adipose tissue. The PBDEs content measured in this study was comparable with data reported in similar samples collected in Spain, Sweden, Belgium and Japan, whilst slightly lower than in the United States. Regarding PCBs, the dominating congeners were No. 138, 153 and 180 representing up to 90% of indicator congeners. The levels of PCBs were similar to those found in other European countries. While no age dependency was found for PBDEs, an increase of PCB and OCP levels with age was observed. Different exposure routes of donors were documented by the absence of the relationship between PCBs and OCPs.     

Global temperature change from the transport sectors: Historical development and future scenarios

Transport affects climate directly and indirectly through mechanisms that operate on very different timescales and cause both warming and cooling. We calculate contributions to the historical development in global mean temperature for the main transport sectors (road transport, aviation, shipping and rail) based on estimates of historical emissions and by applying knowledge about the various forcing mechanisms from detailed studies. We also calculate the development in future global mean temperature for four transport scenarios consistent with the IPCC SRES scenarios, one mitigation scenario and one sensitivity test scenario. There are large differences between the transport sectors in terms of sign and magnitude of temperature effects and with respect to the contributions from the long- and short-lived components. Since pre-industrial times, we calculate that transport in total has contributed 9% of total net man-made warming in the year 2000. The dominating contributor to warming is CO₂, followed by tropospheric O₃. By sector, road transport is the largest contributor; 11% of the warming in 2000 is due to this sector. Likewise, aviation has contributed 4% and rail ～1%. Shipping, on the other hand, has caused a net cooling up to year 2000, with a contribution of ?7%, due to the effects of SO₂ and NOx emissions. The total net contribution from the transport sectors to total man-made warming is ～15% in 2050, and reaches 20% in 2100 in the A1 and B1 scenarios. For all scenarios and throughout the century, road transport is the dominating contributor to warming. Due to the anticipated reduction in sulphur content of fuels, the net effect of shipping changes from cooling to warming by the end of the century. Significant uncertainties are related to the estimates of historical and future net warming mainly due to cirrus, contrails and aerosol effects, as well as uncertainty in climate sensitivity.     

Linking Hydrologic Alteration to Biological Impairment in Urbanizing Streams of the Puget Lowland,Washington, USA1

Abstract: We used a retrospective approach to identify hydrologic metrics with the greatest potential for ecological relevance for use as resource management tools (i.e., hydrologic indicators) in rapidly urbanizing basins of the Puget Lowland. We proposed four criteria for identifying useful hydrologic indicators: (1) sensitive to urbanization consistent with expected hydrologic response, (2) demonstrate statistically significant trends in urbanizing basins (and not in undeveloped basins), (3) be correlated with measures of biological response to urbanization, and (4) be relatively insensitive to potentially confounding variables like basin area. Data utilized in the analysis included gauged flow and benthic macroinvertebrate data collected at 16 locations in 11 King County stream basins. Fifteen hydrologic metrics were calculated from daily average flow data and the Pacific Northwest Benthic Index of Biological Integrity (B‐IBI) was used to represent the gradient of response of stream macroinvertebrates to urbanization. Urbanization was represented by percent Total Impervious Area (%TIA) and percent urban land cover (%Urban). We found eight hydrologic metrics that were significantly correlated with B‐IBI scores (Low Pulse Count and Duration; High Pulse Count, Duration, and Range; Flow Reversals, T_Qmean, and R‐B Index). Although there appeared to be a great deal of redundancy among these metrics with respect to their response to urbanization, only two of the metrics tested – High Pulse Count and High Pulse Range – best met all four criteria we established for selecting hydrologic indicators. The increase in these high pulse metrics with respect to urbanization is the result of an increase in winter high pulses and the occurrence of high pulse events during summer (increasing the frequency and range of high pulses), when practically none would have occurred prior to development. We performed an initial evaluation of the usefulness of our hydrologic indicators by calculating and comparing hydrologic metrics derived from continuous hydrologic simulations of selected basin management alternatives for Miller Creek, one of the most highly urbanized basins used in our study. We found that the preferred basin management alternative appeared to be effective in restoring some flow metrics close to simulated fully forested conditions (e.g., T_Qmean), but less effective in restoring other metrics such as High Pulse Count and Range. If future research continues to support our hypothesis that the flow regime, particularly High Pulse Count and Range, is an important control of biotic integrity in Puget Lowland streams, it would have significant implications for stormwater management.     

Sorption kinetics and its effects on retention and leaching.

Sorption of pesticides to substrates used in biopurification systems is important as it controls the system's efficiency. Ideally, pesticide sorption should occur fast so that leaching of the pesticide in the biopurification system is minimized. Although modeling of pesticide transport commonly assumes equilibrium, this may not always be true in practice. Sorption kinetics have to be taken into account. This study investigated the batch sorption kinetics of linuron, isoproturon, metalaxyl, isoxaben and lenacil on substrates commonly used in a biopurification system, i.e. cow manure, straw, willow chopping, sandy loam soil, coconut chips, garden waste compost and peat mix. The first-order sorption kinetics model was fitted to the observed pesticide concentrations versus time resulting in an estimated kinetic rate constant alpha. Sorption appeared to be fast for the pesticides linuron and isoxaben, pesticides which were classified as immobile, while less mobile pesticides displayed an overall slower sorption. However, the substrate does not seem to be the main parameter influencing the sorption kinetics. Coconut chips, which is a substrate with a high organic matter content showed slow sorption for most of the pesticides. The effect of different estimated alpha values on the breakthrough of pesticides through a biopurification system was evaluated using the HYDRUS 1D model. Significant differences in leaching behavior were observed as a result of the obtained differences in sorption kinetics.     

Do wood mice (Apodemus sylvaticus L.) use food selection as a means to reduce heavy metal intake?

Food preference of wood mice from two with heavy metals polluted sites and two unpolluted sites was tested under laboratory and field conditions with two-way choice experiments. In the laboratory, wood mice preferred to eat acorns from unpolluted sites over acorns from polluted sites. Previous experience with polluted food had no influence on food choice. Preference was negatively related to acorn metal content. Furthermore, the nutrient content of the acorn endosperm was consistently lower in polluted sites. We therefore conclude that wood mice used absolute metal concentration in the acorn, nutrient content, or both as a food selection cue. The results of the laboratory experiment could not be confirmed under field conditions. We hypothesized that search time constraints due to the presence of predators, competitors and/or other stress factors in the field have prevented the mice to forage selectively.