Selection of non-dioxin-like PCBs for in vitro testing on the basis of environmental abundance and molecular structure

The non-dioxin-like polychlorinated biphenyls (NDL-PCBs) constitute the major proportion of PCBs found in food and human tissues. It is important to improve our understanding of the toxicity, environmental and human risks associated with the NDL-PCBs, since their toxicology is incompletely characterized and a human health risk assessment is required. This paper discusses the selection of a training set of 20 tri- to hepta-chlorinated biphenyls, PCBs 19,28,47,51,52,53,74,95,100,101,104,118,122,128,136,138,153,170,180, and 190. Suggested for comprehensive screening using in vitro assays to identify critical mechanisms of toxicological action. The selected PCBs form a balanced basis for developing of quantitative structure-activity relationship (QSAR) models for prediction of physicochemical and toxicological properties of non-tested PCB congeners. Chemical and physical properties, environmental abundance and toxicological activities of the congeners were considered during the selection process. A complementary set of PCBs, a reference set, was selected using D-optimal onion design including PCBs 18,20,28,30,37,40,50,54,60,77,82,99,122,132,153,161,170,188,192, and 193. Congeners of this set are well suited for validation of QSAR models developed using the training set. For visualization of the chemical diversity of environmentally abundant PCBs and congeners of the training and reference sets, principal component analysis (PCA) was used. Statistical molecular design was used to verify the structural representation. As a reference structure for dioxin-like PCBs, PCB 126 was added in the training set. The selected set of NDL-PCBs is proposed for use in toxicological testing programs to provide rational basis for risk assessment of the NDL-PCBs.     

Taxing virgin natural resources: Lessons from aggregates taxation in Europe

The objective of this review paper is to analyze the efficiency of environmentally motivated taxes on virgin raw materials. We analyze both the economic-theoretical foundations of virgin natural resource taxation, and the empirical experiences of aggregates taxes i.e., taxes on, for instance, gravel, rock, stone, etc. in three European countries. These include Sweden, Denmark and the United Kingdom. The theoretical analysis indicates that taxing natural resource output or use typically represents a ‘second-best’ policy alternative, which can be used when, for instance, the monitoring of non-point source emissions is difficult or efficient property rights regimes cannot be established. The empirical analysis shows that the European aggregate taxes have assisted in reducing virgin resource use in spite of the relatively low own-price responses. However, generators of recycled materials typically have few incentives to enhance their waste sorting activities in the presence of a tax on virgin materials. Unless additional policies to increase the supply of recycled materials are implemented, supply will not increase much even in the presence of high demand. Finally, although second-best taxes are sometimes motivated by the desire to keep administration costs low, they could come at the cost of improper incentives and of limited policy legitimacy.     

Mining investment and regional development: A scenario-based assessment for Northern Sweden

The way in which mineral development contributes to economic development in the region where it takes place is important for the mining industry’s relations to the local community. The purpose of this paper is to provide an assessment of the regional-economic impacts of a large-scale contemporary iron ore project in Northern Sweden (including two new mines, two processing plants, and one pellet plant). The regional input-output model rAps, provided by the Swedish government agency NUTEK is used, and it explicitly addresses the linkages between demographic development, the labour market, industrial production and the municipal finances in a consistent modelling framework. The simulation results suggest an average employment multiplier of about 2-2.5 during the maximum production phase, indicating that for every 100 jobs in mining about 100-150 jobs are supported elsewhere in the local economy. The positive impacts in this case are made possible in large because of the existing mining cluster and local suppliers in northern Sweden. Still, these results are perhaps best viewed as an indication of the potential for local economic development as they neglect, for instance, potential supply constraints (e.g., attracting the necessary labour force, road infrastructure, etc.). Specific policies to further strengthen the regional linkage effects may therefore be necessary in order for this potential to be realized in practice, and attention would preferably be paid to policy measures that have positive external spillover effects on the surrounding geographical area.     

The presence and partitioning behavior of flame retardants in waste, leachate, and air particles from Norwegian waste-handling facilities

Flame retardants in commercial products eventually make their way into the waste stream.Herein the presence of flame retardants in Norwegian landfills, incineration facilities and recycling sorting/defragmenting facilities is investigated. These facilities handled waste electrical and electronic equipment(WEEE), vehicles, digestate, glass, combustibles, bottom ash and fly ash. The flame retardants considered included polybrominated diphenyl ethers(∑BDE-10) as well as dechlorane plus, polybrominated biphenyls, hexabromobenzene,pentabromotoluene and pentabromoethylbenzene(collectively referred to as ∑FR-7). Plastic,WEEE and vehicles contained the largest amount of flame retardants(∑BDE-10: 45,000–210,000 μg/kg; ∑FR-7: 300–13,000 μg/kg). It was hypothesized leachate and air concentrations from facilities that sort/defragment WEEE and vehicles would be the highest. This was supported for total air phase concentrations(∑BDE-10: 9000–195,000 pg/m~3 WEEE/vehicle facilities, 80–900 pg/m~3 in incineration/sorting and landfill sites), but not for water leachate concentrations(e.g., ∑BDE-10: 15–3500 ng/L in WEEE/Vehicle facilities and 1–250 ng/L in landfill sites). Landfill leachate exhibited similar concentrations as WEEE/vehicle sorting and defragmenting facility leachate. To better account for concentrations in leachates at the different facilities, waste-water partitioning coefficients, Kwastewere measured(for the first time to our knowledge for flame retardants). WEEE and plastic waste had elevated Kwastecompared to other wastes, likely because flame retardants are directly added to these materials. The results of this study have implications for the development of strategies to reduce exposure and environmental emissions of flame retardants in waste and recycled products through improved waste management practices.     

Energy management practices in Swedish energy-intensive industries

Previous studies point out a large (untapped) potential for energy efficiency in industry through the adoption of energy management practices. The aim of this paper is to describe and analyze energy management practices in two different Swedish energy-intensive industries: the pulp and paper industry and the foundry industry. The results show that one third of the studied mills and about two fifths of the studied foundries do not allocate energy costs by means of sub-metering, which probably contributes to reinforce the split incentive problem. Moreover, about one fifth of the mills and about half of the foundries lack a long-term energy strategy. The results also show that only about 40% and 25% respectively of the studied mills and foundries may be categorized as successful when it comes to energy management practices. If energy management is not fully prioritized even in energy-intensive industries – such as the studied foundry and pulp- and paper industry it will, in all probability, not be prioritized in less energy-intensive industrial sectors or countries either, indicating a large untapped potential in regard to cleaner, more environmentally sound, production in the industrial sector.     

Low levels of persistent organic pollutants (POPs) in New Zealand eels reflect isolation from atmospheric sources

Polychlorinated biphenyls (PCBs) and organic pesticides (i.e., DDTs) were measured in long finned eels (Anguilla dieffenbachii) in 17 streams on the west coast of South Island, New Zealand. Very low levels of PCBs and low levels of ppDDE were found. The concentrations of PCBs and ppDDE were not correlated within sites indicating that different processes determined the levels of the two pollutants in New Zealand eels. The PCBs probably originate from atmospheric transport, ppDDE levels are determined by land use and are higher in agriculture areas. The low contamination level of these aquatic systems seems to be a function of a low input from both long and short-range transport as well as few local point sources. No correlation could be found between lipid content and persistent organic pollutants (POPs) concentration (as shown in previous studies) in the eels which could be explained by low and irregular intake of the pollutants.     

Model description of an alternately operated wastewater treatment plant--evaluation of the applicability of SimpleTreat

Alternately operated wastewater treatment plants (WWTPs) are fundamentally different compared to conventional activated sludge WWTPs with respect to flow patterns and aeration in the biological reactors. Several model applications exist for conventional WWTPs, e.g. SimpleTreat, and in this study the effect of substituting a complex discontinuous operation, involving alternating degradation and flow conditions between two reactors, with one single bioreactor with continuos flow (SimpleTreat) has been investigated by setting up two models representing the respective operation schemes. The discontinuous operation induces fluctuations in the outlet concentrations that are not modelled with the single bioreactor model, however, the fluctuations and the associated uncertainties were found to be insignificant compared to the influence of the input parameter uncertainties on the model results. An empirical relationship between an aggregate pseudo-1st order degradation rate for the single bioreactor model and realistic aerobic and anoxic 1st order degradation rates, respectively, has been established. When using this aggregate degradation rate in the single bioreactor model an outlet concentration can be calculated that deviates no more than 2% from the mean outlet concentration from the alternating operation model. For substances with aerobic half-lives longer than approximately 2 h, which is valid for many chemical substances, the aggregate 1st order degradation rate can be set equal to the aerobic 1st order degradation rate.     

Food web structure affects the extinction risk of species in ecological communities

This paper studies the effect of food web structure on the extinction risk of species. We examine 793 different six-species food web structures with different number, position and strength of trophic links and expose them to stochasticity in a model with Lotka–Volterra predator–prey dynamics. The characteristics of species (intrinsic rates of increase as well as intraspecific density dependence) are held constant, but the interactions with other species and characteristics of the food web are varied.     

Vole response to unintentional changes in the chemistry of GM poplars

Summary.  There is an increased interest for the use of GM trees in forestry and several commercially promising lines are now available. However, the ecological implications of the use of GM trees, e.g. effects on non-target natural enemies, have rarely been explored. The aim of this study was to determine if modification of non-defensive traits in GM poplars unintentionally can influence plant chemistry in a way that has consequences for palatability to voles. In a greenhouse experiment, we used two lines, SPS33A and SPS26, of GM hybrid poplars (Populus tremula x tremuloides) with 1.5 and 4 times, respectively, over-expression sucrose-phosphate synthase (SPS). This enzyme plays a central role in sucrose synthesis, affecting cold acclimation, mesophyll sucrose content and biomass production. As a control we used the isogenic unmodified wild type. Stems of these poplars were presented to bank voles and field voles in cafeteria experiments. The concentration of condensed tannins was higher in leaves of lines SPS33A and SPS26 than in the isogenic wild-type and the concentration of nitrogen was higher in line SPS33A than in both the wild-type and line SPS26. Although the bank voles consumed slightly less bark from SPS33A, there were no significant differences in the preference of bank vole or field vole for the different poplar lines. This indicates that the changes in plant chemistry were insufficient to produce any strong herbivore response or that alteration in tannins and nitrogen counteracted each other. Still, changes in the interactions between mammalian herbivores and GM trees are important to consider in future cost-benefits analyses of GM trees.