Substitution modelling in life cycle assessment of municipal solid waste management.

Life cycle assessment (LCA) is gaining importance worldwide in guiding waste management policies. The capacity of co-products such as recycled materials and recovered energy to avoid primary production of equivalent products largely determines the environmental performance of waste treatment technologies. Estimating the reductions in resource use, emissions, and impacts enabled by this substitution of primary production is often the most influential and controversial factor in quantifying the overall environmental performance of a waste management strategy. This study aims to critically evaluate the modelling of substitution in LCAs of recovered material from municipal solid waste management systems (MSWMS) by answering two questions. First, to what extent is substitution modelling transparently documented in the literature? Second, are the substitution ratios justified to represent physically realistic replacement of one product by another? To address these questions, we performed a systematic analysis of 51 LCA studies on MSWMS published in the peer-reviewed literature. We found that 22% of the substitution ratios are only implicitly expressed. A significant proportion of substitution ratios is not justified (65%), while for the remaining 35%, justifications do not represent physically realistic substitutions. We call for more rigor and transparency, and we propose guidance for the documentation of substitution ratios, with the aim of reaching more credible and robust analyses. For the justification of a substitution ratio to be considered physically realistic, information should notably be provided concerning loss of quality, the function performed by substitutable materials, and the sector of use.

Efficacy of surface sampling methods for different types of beryllium compounds.

The objective of the research work was to evaluate the efficiency of three different sampling methods (Ghost Wipe™, micro-vacuum, and ChemTest®) in the recovery of Be dust by assessing: (1) four Be compounds (beryllium acetate, beryllium chloride, beryllium oxide and beryllium aluminium), (2) three different surfaces (polystyrene, glass and aluminium) and (3) inter-operator variation. The three sampling methods were also tested on site in a laboratory of a dental school for validation purposes. The Ghost Wipe™ method showed recovery ranging from 43.3% to 85.8% for all four Be compounds and for all three quantities of Be spiked on Petri dishes, while recovery with the micro-vacuum method ranged from 0.1% to 12.4%. On polystyrene dishes with 0.4 µg Be, the recovery ranged from 48.3% to 81.7%, with an average recovery of 59.4% for Operator 1 and 68.4% for Operator 2. The ChemTest® wipe method with beryllium acetate, beryllium chloride, and AlBeMet® showed analogous results that are in line with the manufacturer's manual, but collection of beryllium oxide was negative. In the dental laboratory, Ghost Wipe™ samplings showed better recovery than the micro-vacuum method. The ratios between the recovered quantities of Be in each location where the Ghost Wipe™ was tested differed substantially, ranging from 1.45 to 64. In the dental laboratory, a faint blue color indicating the presence of Be was observed on the ChemTest® wipes used in two locations out of six. In summary, the Ghost Wipe™ method was more efficient than micro-vacuuming in collecting the Be dust from smooth, non-porous surfaces such as Petri dishes by a factor of approximately 18. The results obtained on site in a dental laboratory also showed better recovery with Ghost Wipes™. However, the ratio of Be recovered by Ghost Wipes™ versus micro-vacuuming was much lower for surfaces where a large amount of dust was present. Wet wiping is preferred over micro-vacuuming for beryllium forms, but this conclusion probably applies to the ultra-low particulate loading levels (0.4 micrograms or less) which was tested in this study.

Beryllium aerosol characteristics in the magnesium and aluminum transformation industry in Quebec: a comparison of four different sampling methodologies.

To examine the influence of the sampling method on beryllium (Be) exposure assessment, a study was conducted in foundries and smelters to contrast the performance of five different dust sampling devices. Six sampling surveys were conducted in four different settings, and both personal and fixed station samples were collected using the following sampling heads: IOM samplers (inhalable dust), 35-mm plastic cassettes (total dust), aluminum SKC cyclones (respirable dust), 8-stage Sierra cascade impactors, and 12-stage MOUDI impactors. In total, beryllium concentrations were determined for 66/68 inhalable dust samples, 62/62 total dust samples, 56/57 respirable dust samples, 54/64 8-stage Sierra samples, and 19/25 12-stage MOUDI samples. In the magnesium foundry and aluminum smelters, the concentrations obtained during specific tasks could exceed the actual permissible exposure limit of the province of Quebec (0.15 microg/m(3)) or of the ACGIH threshold limit value (TLV) (0.05 microg/m(3)). The median of median dust concentration ratios computed from the sampling heads at the fixed station decreased as follows: IOM (1.00) > Sierra (0.76) > 37-mm cassette (0.61) > MOUDI (0.48) > respirable (0.12). The same trends were observed with the ratios of the median of median Be concentrations at the fixed station but with a larger scattering within sampling heads as follows: IOM (1.00) > Sierra (0.69) > 37-mm cassette (0.64) > MOUDI (0.54) > respirable (0.19). The median of median ratios of dust (IOM (1.00) > Sierra (0.56) > 37-mm cassette (0.35) > respirable (0.06)) and Be (IOM (1.00) > Sierra (0.66) > 37-mm cassette (0.48) > respirable (0.11)) in dust were lower, and there was less scattering for the 37-mm cassette and SKC cyclone used during breathing zone sampling than for the same sampling heads at the fixed station. Inhalable aerosol measurements should remain the tool for estimating the risk of exposure to beryllium in these settings until a clear dose response is established for these sampling heads.

Beryllium decontamination with different solvents on different structures.

The objective of the present work was to estimate the efficiency of moistened wipes in removing beryllium with different solutions including Citranox, Alconox, NaCl 5%, Resolve, and Ledizolv on various types of surfaces such as unpainted metal, wood frames, painted metal, concrete, painted concrete, and Plexiglas from three different occupational settings. Of the three plants that were investigated, only surfaces in the aluminium smelter were decontaminated down to the clearance reference level of 0.2 microg 100 cm(-2), with all the solvents used. In the machine tooling and milling department, the clearance level of 0.2 microg 100 cm(-2) was reached after the three decontaminations, with all the solvents. In the machine plant for the military, aerospace, and telecommunications industries, the beryllium concentrations on the concrete wall, before decontamination with the high-pressure gun, were usually >3 microg 100 cm(-2), and concentrations as high as 31 microg 100 cm(-2) were measured. After the high-pressure cleanup, the beryllium concentrations were sometimes reduced by a factor of 10, but never reached the clearance level. Beryllium compounds that had adhered to most types of structures that we attempted to decontaminate were reduced to below the clearance reference value except on concrete floors. There did not seem to be any difference between the decontamination actions for all the solvents used in this study.

Solvent removal of beryllium from surfaces of equipment made of beryllium copper.

Exposure to beryllium compounds, both by inhalation and skin contact, may result in immune sensitization and chronic beryllium disease. The objective of the present research work was to study the feasibility of removing beryllium compounds from the surfaces of devices made of Be-Cu alloy and to estimate the frequency at which the surfaces had to be rubbed in order to evaluate the likelihood that beryllium can be removed from the surfaces by serial wipe sampling at concentrations exceeding the US Department of Energy (DOE) standard limit of 0.2 microg per 100 cm2. The standard limit was exceeded after successive cleanings of moulds and plates made of Be-Cu alloy with solvents such Citranox, an acidic solvent, Alconox, Z-99 and Fantastik, basic solvents, or more neutral solvents such as Luminox and water. Citranox was the best solvent for extracting beryllium from the tested surfaces, while Alconox seemed to be the second best one. In general, warm water, Luminox and Z-99 seemed to be less efficient for extracting Be from all equipment. The results of the present study suggest that Ghost Wipes, when passed across a surface under the firm pressure of an individual's hand, can be used to detect beryllium contamination. However, they seem to show low reliability for quantification. From a safety standpoint in occupational settings, workers should be offered skin protection and respiratory protection if they have to handle devices made of Be-Cu alloy.

Differences in meibomian fatty acid composition in patients with meibomian gland dysfunction and aqueous-deficient dry eye.

AIMS: To evaluate the differences in meibomian fatty acid composition in healthy subjects and in patients suffering from meibomian gland dysfunction or aqueous-deficient dry eye. METHODS: We collected meibomian oil using a sterile Schirmer paper in healthy individuals (n = 20), dry eye patients (aqueous-deficient) (n = 32) and meibomian gland dysfunction (MGD) patients (n = 25) after gentle massage of the lid margin. Meibomian fatty acids were directly transmethylated and analysed using gas chromatography (GC) and GC mass spectrometry. RESULTS: Meibomian fatty acids were similar in healthy individuals and in dry eye patients but were different in MGD patients, who showed significantly higher levels of branched-chain fatty acids (29.8% vs 20.2%) (p<0.0001) and lower levels of saturated fatty acids (9.3 vs 24.6%) (p<0.0001), in particular lower levels of palmitic (C16) and stearic (C18) acids. CONCLUSION: The increase in branched-chain fatty acids may reflect greater quantities of wax and cholesterol esters and triglycerides in meibomian gland excreta. Since wax and cholesterol esters are the main lipids of meibum, these differences may have physical consequences for tear-film lipid-layer fluidity and stability. Meibomian fatty acid composition and particularly the increase in branched chains could be a marker for meibomian gland dysfunction.

[Improvement of dry eye symptoms with polyunsaturated fatty acids]. / Amélioration de la symptomatologie chez des patients atteints de sécheresse oculaire et traités oralement par des acides gras polyinsaturés.

INTRODUCTION: Polyunsaturated fatty acids (PUFAs) are involved in inflammatory pathways via prostaglandins. Conjunctival inflammation is a hallmark of all dry eye syndromes. We investigated the role of dietary n-6 and n-3 fatty acids in patients suffering from ocular dryness. PATIENTS AND METHODS: Seventy-one patients presenting with mild to moderate dry eye syndromes were randomly assigned to Nutrilarm or placebo capsules, twice a day for 6 months. The Schirmer test, BUT, fluorescein staining, and lissamin green stainings were performed at inclusion and after 1, 3, and 6 months. Furthermore, a questionnaire related to the dry eye symptoms and global discomfort was provided at every visit. RESULTS: The Schirmer test, BUT, fluorescein staining, and lissamin green stainings were improved with treatment when compared to placebo but the difference was not statistically significant. The efficacy evaluated by the patients and the investigator were nearly significant (p=0.052 and p=0.054, respectively). For some signs, such as reflex tearing and conjunctival hyperemia, the improvement reached the threshold of significance (p=0.047 and p=0.045, respectively). The same results were found with skin quality and emotional condition, which were improved (61% with treatment versus 36% with placebo). CONCLUSION: This double-masked pilot study shows that PUFAs seem to be an interesting tool to alleviate the symptoms related to dry eye syndrome. These results should be confirmed using a larger study population.

Effects of phosphoramidon, BQ 788, and BQ 123 on coronary and cardiac dysfunctions of the failing hamster heart.

Coronary dysfunctions identified in the presence of chronic heart failure are an important pathophysiologic abnormality that influences the prognosis of the disease. Because the endothelin pathway plays a significant role in the increased peripheral vascular tone associated with heart failure, we hypothesized that the endothelin pathway may be involved in the abnormal coronary vasomotion associated with this pathologic condition. Experiments were carried out in failing hearts (UM-X7.1 cardiomyopathic hamsters, aged 225-250 days) and normal hearts (Syrian LVG hamsters, also aged 225-250 days). Isolated hearts were perfused at constant flow and exposed to the blocker of the generation of endothelin-1 (ET-1), phosphoramidon (10 microM infusion), as well as to the selective ET(A)-receptor antagonist BQ 123 (10 microM infusion) and to a selective ET(B)-receptor antagonist BQ 788 (1 microM infusion). Coronary and cardiac effects of exogenous ET-1 (0.01-100 pmol) were also studied. Phosphoramidon, BQ 788, and BQ 123 did not altered coronary perfusion pressure either in normal or in failing hearts, whereas cardiac contractility was significantly impaired in the presence of phosphoramidon and BQ 123. Coronary sensitivity to exogenous ET-1 did not demonstrate a significant difference between normal and failing hearts [median effective concentration (EC50), 7 pmol in failing hearts vs. 12 pmol in normal hearts; p = NS]. In the presence of exogenous ET-1, cardiac contractility was significantly increased in both groups. In normal hearts, the exogenous ET-1-induced increase in coronary perfusion pressure was completely antagonized by BQ 123, whereas combined administration of BQ 788 and BQ 123 was necessary to induce complete inhibition in failing hearts. The positive inotropic effect elicited by exogenous ET-1 (EC50) was completely abolished in the presence of BQ 123, whereas BQ 788 had no significant effect. Results indicate that the endothelin pathway does not play a significant role in the altered coronary vasomotion observed in this model of chronic heart failure. On the contrary, the endothelin pathway appears to participate in the maintenance of myocardial contractility. According to these observations, administration of an inhibitor of ET-1 synthesis, as well as the use of an ET(A)-receptor antagonist, may be contraindicated in the presence of poor left ventricular function because the endothelin pathway contributes significantly to the maintenance of cardiac contractility.

Myocardial reactive hyperemia in experimental chronic heart failure: evidence for the role of K+ adenosine triphosphate-dependent channels and cyclooxygenase activity.

BACKGROUND: Several studies suggest that coronary perfusion is abnormal in heart failure. The fact that these deficits may results in an altered coronary reserve remains controversial. Therefore, coronary adaptability to short-duration ischemia and the resultant myocardial reactive hyperemia were investigated in a model of chronic heart failure. METHODS AND RESULTS: Experiments were performed in normal and failing hamster hearts (UM-X7.1, aged > 225 days). Heart rate, left ventricular developed pressure, and coronary flow were recorded continuously before and after each 30-second ischemia in isolated perfused heart preparations. Studies were conducted under control conditions and in the presence of four inhibitors of potential mediators of the reactive hyperemia response: the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (30 microM), the adenosine antagonist 8-(p-sulfophenyl)theophylline (50 microM), the K+ cyclic adenosine triphosphate-dependent channel antagonist glibenclamide (10 microM), and the cyclooxygenase inhibitor indomethacin (10 microM). Baseline hemodynamic parameters were all significantly impaired in failing hearts. Under control conditions, failing hearts were able to respond adequately to a 30-second ischemia: repayment-to-debt ratio averaged 1.02 +/- 0.09 as compared with 1.10 +/- 0.09 in normal hearts (P = NS). All inhibitors significantly reduced basal coronary perfusion except for indomethacin. Of the four inhibitors of potential mediators of the myocardial reactive hyperemic response, only glibenclamide and indomethacin impaired the repayment-to-debt ratio. In their presence, repayment-to-debt ratio was reduced by 40% of the baseline response (P < .01) without significant difference between normal and failing hearts. On the contrary, NG-nitro-L-arginine methyl ester and 8-(p-sulfophenyl)theophylline did not alter the repayment-to-debt ratio. CONCLUSIONS: These observations demonstrate the capacity of the failing heart to tolerate short-duration ischemia despite the presence of significant alterations in its basal coronary perfusion. In addition, results suggest that activation of K+ adenosine triphosphate-dependent channels and the presence of cyclooxygenase by-products are important determinants of coronary adaptation to short-duration ischemia in this model of chronic heart failure.

Overexpression of vsr in Escherichia coli is mutagenic.

Overexpression of vsr in Escherichia coli stimulates transition and frameshift mutations. The pattern of mutations suggests that mutagenesis is due to saturation or inactivation of dam-directed mismatch repair.

Cloning, sequencing, and expression in Escherichia coli of the D-hydantoinase gene from Pseudomonas putida and distribution of homologous genes in other microorganisms.

Pseudomonas putida DSM 84 produces N-carbamyl-D-amino acids from the corresponding D-5-monosubstituted hydantoins. The gene encoding this D-hydantoinase enzyme was cloned and expressed in Escherichia coli. The nucleotide sequence of the 1.8-kb insert of subclone pGES19 was determined. One open reading frame of 1,104 bp was found and was predicted to encode a polypeptide with a molecular size of 40.5 kDa. Local regions of identity between the predicted amino acid sequence and that of other known amidohydrolases (two other D-hydantoinases, allantionase and dihydroorotase) were found. The D-hydantoinase gene was used as a probe to screen DNA isolated from diverse organisms. Within Pseudomonas strains of rRNA group I, the probe was specific. The probe did not detect D-hydantoinase genes in pseudomonads not in rRNA group I, other bacteria, or plants known to express D-hydantoinase activity.