Light and electronmicroscopic studies of the acute and long-term toxic effects of N-nitrosodipropylamine and N-methylnitrosurea on the marine mussel Mytilus edulis

The acute (1) and long-term (2) toxic effects of N-nitrosodipropylamine (NDPA) and N-methylnitrosurea (NMU) were studied by light and electronmicroscopy following injection of the chemicals into the foot of the mussels Mytilus edulis (L.) (1) Mussels reveived one injection of NDPA at concentrations of 0.25, 0.5, 1.0, and 2.0 mg NDPA mussel^-1, and one injection of NMU at concentrations of 0.25, 0.5, 1.0, and 4.0 mg NMU mussel^-1. Within 12d, necrosis of the epithelial lining of the digestive diverticula took place, and the vesicular connective tissue in the digestive diverticula were heavily infiltrated by eosinophilic granular leucocytes. (2) Mussels received four weekly injections of 0.5 mg NDPA mussel^-1, and 0.5 mg NMU mussel^-1. NDPA-exposed mussels were examined for a period of 17 weeks, and NMU-exposed mussels were examined for a period of 24 weeks. Both chemicals produced progressive tissue damage, characterized by destruction of digestive tubules and ducts in the digestive diverticula. Destroyed tubules and ducts were replaced by collagenous scars, and granulocytomas were frequently seen.     

Attitudes towards the conservation of biological diversity—A case study in Kristianstad Municipality,Sweden

Human actions towards land, freshwater and oceans have already caused biodiversity to decline. This study aims to investigate attitudes towards the conservation of biological biodiversity among different groups in a Swedish city, Kristianstad. An inquiry including statements measuring attitudes towards the conservation of habitats, animals and plants, to the biological diversity within selected local areas, to global and national areas, and to societal issues, was replied to by 271 persons. Deciduous forests, birds and wild flowers were given highest priority. An area categorized as wetland including lakeshore meadows with a rich bird life was prioritized as most important for conservation while a forest area was chosen as best for recreation. The experts gave lower priority to arable land, urban parks, domestic animals, agricultural and garden plants and to conifer forests compared to the other groups. Knowledge about what people in general value as important could facilitate the future planning of nature areas in the city of Kristianstad.     

Secular trends of atmospheric methane (CH4)

Due partly to human activities the present yearly emissions of CH₄ exceed the atmospheric sinks, thus leading to a 1.2–1.9% per year atmospheric increase in the concentration of CH₄. New evidence based on studies of polar ice cores suggests that several hundred years ago the concentrations of CH₄ were perhaps only half of current values. These diverse findings are tied together in a single unified logistic model of atmospheric concentrations past, present and future. Using realistic growth rates of the sources of CH₄ caused by human activities, the model explains the concentrations and current growth rates. It also predicts that a doubling of CH₄ relative to present levels is possible given the long (9-year) atmospheric lifetime. Such increases of CH₄ concentrations may have already perturbed our global environment and may continue to do so in the future. The environmental effects include increased surface temperature of the earth, additional O₃ and CO in the clean non-urban atmosphere, depletions of tropospheric OH radicals, but perhaps also protection of the stratospheric ozone layer from destruction by man-made fluorocarbons.     

Measuring visual opacity using digital imaging technology

The U.S. Environmental Protection Agency (EPA) Reference Method 9 (Method 9) is the preferred enforcement approach for verifying facility compliance with federal visible opacity standards. Supporters of Method 9 have cited its flexibility and low cost as important technological and economic advantages of the methodology. The Digital Opacity Compliance System (DOCS), an innovative technology that employs digital imaging technology for quantifying visible opacity, has been proposed as a technically defensible and economically competitive alternative to Method 9. Results from the field application of the DOCS at EPA-approved Method 9 smoke schools located in Ogden, UT, Augusta, GA, and Columbus, OH, demonstrated that, under clear sky conditions, the DOCS consistently met the opacity error rate established under Method 9. Application of hypothesis testing on the smoke school data set confirmed that the DOCS was equivalent to Method 9 under clear sky conditions. Under overcast sky conditions, human observers seemed to be more accurate than the DOCS in measuring opacity. However, within the smoke school environment, human observers routinely employ backgrounds other than sky (e.g., trees, telephone poles, billboards) to quantify opacity on overcast days. Under conditions that compel the use of sky as plume background (e.g., emission stacks having heights above the tree line), the DOCS appears to be a more accurate methodology for quantifying opacity than are human observers.     

Analysis of indoor gaseous formic and acetic acid, using radial diffusive samplers

A diffusive sampling method for the determination of gaseous acetic and formic acids, using a radial symmetry diffusive sampler, has been optimised for a 7-day exposure time in this study. Sampling rate determinations were performed on data obtained from a dynamic exposure chamber, simulating the indoor conditions of an empty, closed, room, at room temperature and minimal wind speed. Analysis has been performed by means of ion chromatography. The sampling rates for formic acid concentrations of 128 microg m(-3) and 1248 microg m(-3) were determined to be 91.2 +/- 3.9 ml min(-1) and 111.6 +/- 2.8 ml min(-1), respectively. The acetic acid sampling rate was independent of the concentration in the range 160 microg m(-3)-1564 microg m(-3), and amounted to 97.3 +/- 3.1 ml min(-1). Experimentally determined sampling rates showed deviations of 3% for acetic acid, and 3-21% for formic acid, in relation to theoretically derived values. The blank values were as low as 1.69 +/- 0.07 microg for formic acid and 1.21 +/- 0.14 microg for acetic acid, and detection limits lower than 0.5 microg m(-3) could be achieved, which is an improvement of 98-99% compared to previously validated diffusive sampling methods. This study describes the first step of an extended validation program in which the applicability of these types of samplers for the measurement of organic acids will be validated and optimised for the environmental conditions typical for museum showcases.     

Effects of aquatic humic substances on a hydrophobic ultrafiltration membrane

Natural humic surface water (pH 5.9), ion exchanged samples of the same water (pH 5.5), and aqueous solutions of isolated humic substances at pH 4.5, 5.5 and 6.5, respectively, were ultrafiltered (15°C, 0.5 bar) using hydrophobic polysulfone membranes (GR51) in a cross-flow flat sheet module. The used membrane did not completely retain natural organic matter from the surface water and the addition of complexing metals did not affect the retention any further. The changes which were induced in the membranes during each filtration run were studied by simultaneous streaming potential and flux measurements in 0.01 M KCl solutions. Zeta potentials were calculated based on the streaming potentials and the results showed changes towards more negative values for all the samples due to adsorption of organic matter onto the surface of the membrane pores. Humic acid affected the membrane charges more than fulvic acid. High ionic strength and low pH enhanced flux reduction and fouling. Filtration of natural waters caused more pore plugging and flux reduction than filtration of solutions of the isolated humic substances.     

Water Consumption in the Production of Ethanol and Petroleum Gasoline

We assessed current water consumption during liquid fuel production, evaluating major steps of fuel lifecycle for five fuel pathways: bioethanol from corn, bioethanol from cellulosic feedstocks, gasoline from U.S. conventional crude obtained from onshore wells, gasoline from Saudi Arabian crude, and gasoline from Canadian oil sands. Our analysis revealed that the amount of irrigation water used to grow biofuel feedstocks varies significantly from one region to another and that water consumption for biofuel production varies with processing technology. In oil exploration and production, water consumption depends on the source and location of crude, the recovery technology, and the amount of produced water re-injected for oil recovery. Our results also indicate that crop irrigation is the most important factor determining water consumption in the production of corn ethanol. Nearly 70% of U.S. corn used for ethanol is produced in regions where 10–17 liters of water are consumed to produce one liter of ethanol. Ethanol production plants are less water intensive and there is a downward trend in water consumption. Water requirements for switchgrass ethanol production vary from 1.9 to 9.8 liters for each liter of ethanol produced. We found that water is consumed at a rate of 2.8–6.6 liters for each liter of gasoline produced for more than 90% of crude oil obtained from conventional onshore sources in the U.S. and more than half of crude oil imported from Saudi Arabia. For more than 55% of crude oil from Canadian oil sands, about 5.2 liters of water are consumed for each liter of gasoline produced. Our analysis highlighted the vital importance of water management during the feedstock production and conversion stage of the fuel lifecycle.     

Safety in construction – a comprehensive description of the characteristics of high safety standards in construction work, from the combined perspective of supervisors and experienced workers

Introduction

The often applied engineering approach to safety management in the construction industry needs to be supplemented by organizational measures and measures based on how people conceive and react to their social environment. This requires in-depth knowledge of the broad preconditions for high safety standards in construction. The aim of the study was to comprehensively describe the preconditions and components of high safety standards in the construction industry from the perspective of both experienced construction workers and first-line managers.

Method

Five worker safety representatives and 19 first-line managers were interviewed, all strategically selected from within a large Swedish construction project. Phenomenographic methodology was used for data acquisition and analysis and to categorize the information. Nine informants verified the results.

Results

The study identified four main categories of work safety preconditions and components: (1) Project characteristics and nature of the work, which set the limits of safety management; (2) Organization and structures, with the subcategories planning, work roles, procedures, and resources; (3) Collective values, norms, and behaviors, with the subcategories climate and culture, and interaction and cooperation; and (4) Individual competence and attitudes, with the subcategories knowledge, ability and experience, and individual attitudes.

Discussion

The results comprehensively describe high safety standards in construction, incorporating organizational, group, individual, and technical aspects. High-quality interaction between different organizational functions and hierarchical levels stood out as important aspects of safety. The results are discussed in relation to previous research into safety and into the social-psychological preconditions for other desired outcomes in occupational settings.

Impact on Industry

The results can guide construction companies in planning and executing construction projects to a high safety standard.     

Patterns and concentration levels of polybrominated diphenyl ethers (PBDEs) in placental tissue of women in Denmark

The levels and congener patterns of PBDEs were investigated in human placental samples in Denmark. The median concentrations of ∑PBDE_tri-hepta and BDE-209 in the 50 samples were 1.22 and 1.14 ng g⁻¹ lw, respectively, with the total sum ranging from 0.51 to 17.1 ng g⁻¹ lw, which is similar to previous placental studies. The PBDE content in placental tissue was dominated by BDE-209, which accounted for approximately 50% of the total amount of PBDEs. BDE-47, -99, and -153 were detected in all samples. Approximately equal amounts of BDE-47 and BDE-153 were observed in the placental tissue, which is in agreement with previous European studies of human serum. Principal Component Analysis (PCA) was performed to analyze congener patterns within and between mothers. The loading plot showed groupings of the measured PBDE variables in three groups, representative of Penta-, Octa- and Deca-BDE technical mixtures. Congeners representing the individual technical mixtures were close to orthogonal or inversely correlated, indicating variation in the congener patterns of internal exposure corresponding to the patterns of technical mixtures used in products. Visualisation of the participant objects according to body mass index (BMI), revealed inherent congener patterns (19% X-variance) showing increased frequency for participants within the highest BMI group to have elevated concentrations of BDE-209 in the placental tissue.