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ABSTRACT: Currently, the public has access to a variety of databases containing mutagenicity and carcinogenicity data. These resources are crucial for the toxicologists and regulators involved in the risk assessment of chemicals, which necessitates access to all the relevant literature, and the capability to search across toxicity databases using both biological and chemical criteria. Towards the larger goal of screening chemicals for a wide range of toxicity end points of potential interest, publicly available resources across a large spectrum of biological and chemical data space must be effectively harnessed with current and evolving information technologies (i.e. systematised, integrated and mined), if long-term screening and prediction objectives are to be achieved. A key to rapid progress in the field of chemical toxicity databases is that of combining information technology with the chemical structure as identifier of the molecules. This permits an enormous range of operations (e.g. retrieving chemicals or chemical classes, describing the content of databases, finding similar chemicals, crossing biological and chemical interrogations, etc.) that other more classical databases cannot allow. This article describes the progress in the technology of toxicity databases, including the concepts of Chemical Relational Database and Toxicological Standardized Controlled Vocabularies (Ontology). Then it describes the ISSTOX cluster of toxicological databases at the Istituto Superiore di Sanitá. It consists of freely available databases characterised by the use of modern information technologies and by curation of the quality of the biological data. Finally, this article provides examples of analyses and results made possible by ISSTOX.
Mutagenesis 03/2013; · 3.18 Impact Factor
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ABSTRACT: This paper presents a new curated database on in vivo micronucleus mutagenicity results, called ISSMIC. It is freely available at: http://www.iss.it/ampp/dati/cont.php?id=233&lang=1&tipo=7. The experimental results were critically reviewed, and evidence on target cell exposure was considered as well. The inspection of ISSMIC demonstrates that a large proportion of reported negative results in the literature (231 out 566 ISSMIC chemicals) lack a clear-cut, direct demonstration of toxicity at the target cells. Using this updated database, the predictive value of a compilation of Structural Alerts (SA) for in vivo micronucleus recently implemented in the expert system Toxtree was investigated. Individually, most of the SA showed a high Positive Predictivity (∼80%), but the need for further expanding the list of alerts was pointed out as well. The role of in vivo micronucleus in strategies for carcinogenicity prediction was re-evaluated. In agreement with previous analyses, the data point to a low overall correlation with carcinogenicity. In addition, given the cost in animal lives and the time required for the experimentation, in many programs, the in vivo tests are used only to assess in vitro positive results. The ability of in vivo micronucleus to identify real positives (i.e. carcinogens) among chemicals positive in Salmonella or among chemicals inducing in vitro chromosomal aberrations was studied. It appears that the in vivo micronucleus test does not have added value and rather impairs the prediction ability of the in vitro tests alone. The overall evidence indicates that in vivo micronucleus--in its present form--cannot be considered an useful tool for routine genotoxicity testing but should be used in targeted mechanistic studies.
Mutagenesis 09/2011; 27(1):87-92. · 3.18 Impact Factor
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ABSTRACT: In Part 1 of this article we developed an approach for the calculation of cancer effect measures for life cycle assessment (LCA). In this article, we propose and evaluate the method for the screening of noncancer toxicological health effects. This approach draws on the noncancer health risk assessment concept of benchmark dose, while noting important differences with regulatory applications in the objectives of an LCA study. We adopt the centraltendency estimate of the toxicological effect dose inducing a 10% response over background, ED10, to provide a consistent point of departure for default linear low-dose response estimates (betaED10). This explicit estimation of low-dose risks, while necessary in LCA, is in marked contrast to many traditional procedures for noncancer assessments. For pragmatic reasons, mechanistic thresholds and nonlinear low-dose response curves were not implemented in the presented framework. In essence, for the comparative needs of LCA, we propose that one initially screens alternative activities or products on the degree to which the associated chemical emissions erode their margins of exposure, which may or may not be manifested as increases in disease incidence. We illustrate the method here by deriving the betaED10 slope factors from bioassay data for 12 chemicals and outline some of the possibilities for extrapolation from other more readily available measures, such as the no observable adverse effect levels (NOAEL), avoiding uncertainty factors that lead to inconsistent degrees of conservatism from chemical to chemical. These extrapolations facilitated the initial calculation of slope factors for an additional 403 compounds; ranging from 10(-6) to 10(3) (risk per mg/kg-day dose). The potential consequences of the effects are taken into account in a preliminary approach by combining the betaED10 with the severity measure disability adjusted life years (DALY), providing a screening-level estimate of the potential consequences associated with exposures, integrated over time and space, to a given mass of chemical released into the environment for use in LCA.
Risk Analysis 11/2002; 22(5):947-63. · 2.37 Impact Factor
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ABSTRACT: Life cycle assessment (LCA) is a framework for comparing products according to their total estimated environmental impact, summed over all chemical emissions and activities associated with a product at all stages in its life cycle (from raw material acquisition, manufacturing, use, to final disposal). For each chemical involved, the exposure associated with the mass released into the environment, integrated over time and space, is multiplied by a toxicological measure to estimate the likelihood of effects and their potential consequences. In this article, we explore the use of quantitative methods drawn from conventional single-chemical regulatory risk assessments to create a procedure for the estimation of the cancer effect measure in the impact phase of LCA. The approach is based on the maximum likelihood estimate of the effect dose inducing a 10% response over background, ED10, and default linear low-dose extrapolation using the slope betaED10 (0.1/ED10). The calculated effects may correspond to residual risks below current regulatory compliance requirements that occur over multiple generations and at multiple locations; but at the very least they represent a "using up" of some portion of the human population's ability to accommodate emissions. Preliminary comparisons are performed with existing measures, such as the U.S. Environmental Protection Agency's (U.S. EPA's) slope factor measure q1*. By analyzing bioassay data for 44 chemicals drawn from the EPA's Integrated Risk Information System (IRIS) database, we explore estimating ED10 from more readily available information such as the median tumor dose rate TD50 and the median single lethal dose LD50. Based on the TD50, we then estimate the ED10 for more than 600 chemicals. Differences in potential consequences, or severity, are addressed by combining betaED10 with the measure disability adjusted life years per affected person, DALYp. Most of the variation among chemicals for cancer effects is found to be due to differences in the slope factors (betaED10) ranging from 10(-4) up to 10(4) (risk of cancer/mg/kg-day).
Risk Analysis 11/2002; 22(5):931-46. · 2.37 Impact Factor
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ABSTRACT: The inclusion of fate and exposure is a central issue in Life Cycle Impact Assessment (LCIA). According to the framework developed
by the Society of Environmental Toxicity and Chemistry (SETAC), fate and exposure route are included through a fate coefficient
which makes the link between an emission and the related increase in concentration.
In the Critical surface-time 95 methodology, fate factors of air pollutants are determined empirically at a world level as
the ratio of measured concentration to the total estimated emission flow. Based on a detailed study performed for seventeen
pollutants, a correlation is developed to predict fate factors from the residence time. Variation of a factor 10000 arc observed
for the fate coefficient. Empirical fate factors are compared to modelled fate factors and are found to have a similar order
of magnitude.
The International Journal of Life Cycle Assessment 01/1997; 2(2):104-110. · 2.36 Impact Factor
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Pierre Crettaz
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ABSTRACT: Life Cycle Assessment (LCA) is a tool developed to evaluate the environmental impact of a product or a system. After a decade of research in the LCA field, significant progress has been achieved but methodologies for the assessment of toxicological impacts on human health are still in the development phase. This dissertation contributes to the research required in this field. More specifically, its main objective is to develop a Life Cycle Impact Assessment (LCIA) procedure for human health respecting the guidance developed under the umbrella of the Society of Environmental Toxicology and Chemistry (SETAC). This means that we aim to implement an original procedure to quantify the potential carcinogenic and noncarcinogenic effects of toxic releases on human health (chapters 2 and 3), and to develop a new method describing the fate of atmospheric releases and the resulting exposure on humans (chapter 4). A framework summarized in figure 5.1 is also proposed to combine the effect assessment with the fate and exposure assessment, in order to derive a so-called human damage factor (chapter 5). A set of heavy metals (cadmium, chromium(VI), chromium(III), copper, methylmercury, beryllium, lead and inorganic arsenic) and of criteria air pollutants (CO, SO2, NOx and fine particles) is chosen for a full application of the procedure developed in this dissertation. The use of this procedure to the Cycleaupe case study is also part of the objectives of this research. This study aims to determine whether systems using rainwater or reducing water consumption are "friendlier" from an environmental perspective than conventional toilet flushing (chapter 6). Figure 5.1. Overview of the framework proposed in this thesis for assessing the damage induced on human health by a toxic released into air. In chapters 2 and 3, a new paradigm based on the effect dose ED10h is derived from the Risk Assessment concept of benchmark dose. It is proposed and explored for the first time in LCIA. The ED10h is defined as the best estimate of the dose which induces a 10% added risk over background for humans. Carcinogenic and noncarcinogenic risks towards humans are characterized by drawing a straight line from the ED10h down to the origin of the dose-response function. The slope of this straight line is called the slope factor and is denoted βED10. The linear dose-response function without threshold, which is assumed in this ED10-approach, is discussed. The ED10h is calculated for chemicals with bioassay data available in the Integrated Risk Information Service (IRIS) database provided by the US Environmental Protection Agency (US EPA). New correlations between the ED10h and the more widely available tumor dose TD50a (for carcinogenic effects) and the No Observable Adverse Effect Level NOAEL (for noncarcinogenic effects) are determined. They are applied to quantify the slope factor of more than 900 chemicals. A weighting of the different health outcomes associated with chemicals is proposed, based upon the Disability Adjusted Life Years per affected person (DALYp) concept. For carcinogenic endpoints, the DALYp is calculated for different types of tumors, using data reported in the literature. This shows that all cancers have more or less the same severity and an average DALYp of 11.1 years of life lost per affected person is derived. For noncarcinogenic effects, a simplified classification of the adverse effects into three categories is chosen and a DALYp of 11.1, 1.1 and 0.11 years of life lost per affected person is respectively assigned to each of the three categories. Finally, the slope factor βED10 and the DALYp for each substance are combined together in an original way to derive its effect factor. This effect factor is expressed in years of life lost per absorbed mass. Appendix 1.1 summarizes the effect factors calculated for more than 900 toxic releases. Effect factors for carcinogenic outcomes range from 1.3·10-9 for cinnamyl anthranilate up to 3.4·10-1 [yr lost / mg absorbed] for 2,3,7,8-tetrachlorodibenzo-p-dioxin. Effect factors for noncarcinogenic endpoints range from 4.2·10-12 for 1-Chloro-1,1-difluoroethane to 1.4·10-3 [yr lost / mg absorbed] for beryllium. In chapter 4, a semi-empirical approach is developed to evaluate the fate and exposure for atmospheric releases of metals, carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOx) and fine particles. For that purpose, we apply for the first time in LCA the concept of exposure efficiency, which is defined as the ratio between the dose absorbed by the population and the emission inducing that absorption. Three types of exposure efficiency are defined for a world release into air of a given compound. A specific exposure efficiency is directly based on the rural and urban concentrations inhaled by humans. A continental exposure efficiency is defined by considering an uniform world continental concentration over urban and rural inhabited regions (marine and desert regions are excluded). A global exposure efficiency issimilarly defined from the global world concentration of a substance. Exposure efficiencies are calculated for fine particles, CO, NOx and SO2. The specific exposure efficiency ranges from 3.9·10-6 to 2.4·10-5 [mg absorbed / mg emitted], demonstrating that only a very small fraction of an air release is inhaled by humans. The exposure efficiency for metals after inhalation is assumed to be equal to the exposure efficiency for fine particles, since airborne metals are attached to particulate matter. If atmospheric deposition on an agricultural soil occurs, humans can be exposed through a transfer into food products. A first evaluation of this transfer indicates that it can increase the exposure efficiency of metals released into air by a factor 5 up to 70. Specific exposure efficiencies are selected in this thesis to describe the fate and exposure of atmospheric releases. We show for the first time that specific exposure efficiencies are higher by a factor 3 than continental exposure efficiencies, indicating that the use of one-box continental models tend to underestimate the exposure efficiency that can be expected in the real world. This is due to the fact that higher emissions occur in highly populated regions. As a first approximation, the factor 3 could be used as a corrective factor to derive the specific exposure efficiency from the exposure efficiency predicted by one-box continental models. In chapter 5, exposure efficiencies presented in chapter 4 and effect factors presented in chapters 2 and 3 are multiplied to derive the so-called Human Damage Factors (HDF). The damage factors are expressed in years of life lost per emitted mass. Using that factor, the emission of a substance can be converted into its potential damage induced on humans. The damage factors are calculated for NOx, SO2, CO and fine particles, as well as for the selected set of metals released into air or into agricultural soils (see appendix 1.2 for the summarized results). When the transfer into food products is not accounted for, the damage factors for the studied metals range from 1.7·10-11 for chromium(VI) up to 1.3·10-8 [yr lost / mg emitted] for beryllium. Lead has the highest damage factor (1.9·10-8 [yr lost / mg emitted]) if transfer into food products is considered. Damage factors ranging from 2.7·10-10 to 6.6·10-10 [yr lost / mg emitted] are found for NOx, SO2 and fine particles, while carbon monoxide is characterized by a damage factor 103-folds lower. Per emitted mass, metals inhaled by humans induce damages of the same order of magnitude than NOx, SO2 and fine particles; when atmospheric deposition on agricultural soils and its subsequent transfer into food are accounted for, metals present higher damage factors. An indirect validation of the damage factors is presented for SO2, NOx, CO, fine particles and some metals, by applying their damage factors to their total emissions over Switzerland and Europe. The evaluated damages are plausible and in accordance with results reported in other studies. In chapter 6, a Life Cycle Analysis is performed to compare five scenarios for toilets flushing. This LCA is the first one carried out on the whole water cycle, including both thesimilarly defined from the global world concentration of a substance. Exposure efficiencies are calculated for fine particles, CO, NOx and SO2. The specific exposure efficiency ranges from 3.9·10-6 to 2.4·10-5 [mg absorbed / mg emitted], demonstrating that only a very small fraction of an air release is inhaled by humans. The exposure efficiency for metals after inhalation is assumed to be equal to the exposure efficiency for fine particles, since airborne metals are attached to particulate matter. If atmospheric deposition on an agricultural soil occurs, humans can be exposed through a transfer into food products. A first evaluation of this transfer indicates that it can increase the exposure efficiency of metals released into air by a factor 5 up to 70. Specific exposure efficiencies are selected in this thesis to describe the fate and exposure of atmospheric releases. We show for the first time that specific exposure efficiencies are higher by a factor 3 than continental exposure efficiencies, indicating that the use of one-box continental models tend to underestimate the exposure efficiency that can be expected in the real world. This is due to the fact that higher emissions occur in highly populated regions. As a first approximation, the factor 3 could be used as a corrective factor to derive the specific exposure efficiency from the exposure efficiency predicted by one-box continental models. In chapter 5, exposure efficiencies presented in chapter 4 and effect factors presented in chapters 2 and 3 are multiplied to derive the so-called Human Damage Factors (HDF). The damage factors are expressed in years of life lost per emitted mass. Using that factor, the emission of a substance can be converted into its potential damage induced on humans. The damage factors are calculated for NOx, SO2, CO and fine particles, as well as for the selected set of metals released into air or into agricultural soils (see appendix 1.2 for the summarized results). When the transfer into food products is not accounted for, the damage factors for the studied metals range from 1.7·10-11 for chromium(VI) up to 1.3·10-8 [yr lost / mg emitted] for beryllium. Lead has the highest damage factor (1.9·10-8 [yr lost / mg emitted]) if transfer into food products is considered. Damage factors ranging from 2.7·10-10 to 6.6·10-10 [yr lost / mg emitted] are found for NOx, SO2 and fine particles, while carbon monoxide is characterized by a damage factor 103-folds lower. Per emitted mass, metals inhaled by humans induce damages of the same order of magnitude than NOx, SO2 and fine particles; when atmospheric deposition on agricultural soils and its subsequent transfer into food are accounted for, metals present higher damage factors. An indirect validation of the damage factors is presented for SO2, NOx, CO, fine particles and some metals, by applying their damage factors to their total emissions over Switzerland and Europe. The evaluated damages are plausible and in accordance with results reported in other studies. In chapter 6, a Life Cycle Analysis is performed to compare five scenarios for toilets flushing. This LCA is the first one carried out on the whole water cycle, including both the water supply and the wastewater treatment. The drinking water supply system, the rainwater recuperation system and the wastewater treatment system are included in the system boundaries. Results demonstrate that economic toilets (3.5 [l/flushing]) lead to a significant reduction of the energy requirements compared to conventional toilets (9 [l/flushing]). A conventional water supply and a rainwater recuperation with a storage tank of 10 m3 are characterized by similar energy consumption. A rainwater storage tank of 20 m3, designed to be completely independent of the conventional water supply system, is energetically disadvantageous. Calorific losses, linked to the temperature increase of flushing water within the house, have a significant contribution to the energy requirement. The advantage of economic toilets is confirmed when looking at the inventory emissions. An initial LCIA was performed using the critical surface-time CST95 method of Jolliet and Crettaz [1997]. It showed that the conventional scenario using economic toilets (CONVeco) is the most advantageous for all impact classes. When applying the human damage factors developed in this thesis (see chapter 5), the conventional scenario (CONVeco) is still characterized by lower impacts on humans than the recuperation scenario (REC10eco). However, the substances having the major effect on human health differ from those found with the CST95 method; reasons for that change are discussed. L'Analyse de Cycle de Vie (ACV) permet d'évaluer l'impact environnemental d'un produit ou d'un système. Après plusieurs années de recherche dans le domaine des ACV, des progrès significatifs ont été réalisés. Cependant, les méthodologies d'évaluation de l'impact toxicologique des substances toxiques sur la santé humaine sont toujours en phase de développement. La présente thèse contribue à la recherche supplémentaire requise dans ce domaine. Plus spécifiquement, son objectif principal est de développer une méthode d'évaluation de l'impact environnemental pour la santé humaine. Ladite méthode doit respecter la structure développée par la société européenne de toxicologie et de chimie (SETAC). Cette thèse vise donc à mettre en place une procédure permettant de quantifier les effets cancérigènes et non cancérigènes des substances chimiques sur la santé humaine (chapitres 2 et 3). Une méthode décrivant le devenir des substances émises dans l'air et l'exposition en résultant sur les humains est également proposée (chapitre 4). Un cadre d'analyse (voir figure 5.1) est proposé afin de combiner l'évaluation de l'effet toxique, avec l'évaluation du devenir des substances. Un facteur de dommage sur l'homme peut alors être déduit (chapitre 5). Un ensemble de métaux lourds (cadmium, chrome(VI), chrome(III), cuivre, méthylemercure, béryllium, plomb et arsenic inorganique) et de polluants atmosphériques (CO, SO2, NOx et particules fines) est choisi pour une application complète de la méthode développée dans cette thèse. La méthode est testée à l'étude dénommée "Cycleaupe". Cette étude vise à déterminer si les systèmes utilisant l'eau pluviale ou réduisant la consommation d'eau induisent une charge environnementale moindre qu'un rinçage conventionnel des toilettes (chapitre 6). Figure 5.1. Overview of the framework proposed in this thesis for assessing the damage induced on human health by a toxic released into air. Dans les chapitres 2 et 3, une nouvelle approche, basée sur la dose d'effet notée ED10h, est dérivée du concept de "benchmark dose" développé en Evaluation du Risque. Elle est proposée et explorée pour la première fois en ACV dans cette thèse. L'ED10h est définie comme la meilleure estimation de la dose induisant un risque pour les hommes de 10% par rapport au niveau de base. Le risque cancérigène et non cancérigène pour les hommes se caractérise en traçant une ligne droite à partir de ED10h vers l'origine de la fonction "dose-réponse". La pente de cette droite est appelée le facteur de pente et est dénoté βED10. La fonction "dose-réponse" linéaire et sans seuil, qui est supposée dans l'approche proposée, est discutée. L'ED10h est calculée pour des substances toxiques ayant des données d'essai sur animaux disponibles dans la base de données IRIS (Integrated Risk Information Service database) de l'Agence Américaine de l'Environnement (US EPA). Les corrélations entre l'ED10h et les paramètres plus largement disponibles comme la dose de tumeur TD50a (pour des effets cancérigènes) et la dose non associée à un effet nocif notable NOAEL (pour des effets non cancérigènes) sont déterminées. Elles sont appliquées afin de quantifier le facteur de pente de plus de 900 substances. Une pondération des différents types d'effets nocifs sur la santé humaine est proposée en se basant sur le concept des années de vie perdue par personne affectée (DALYp). Pour les effets cancérigènes, les DALYp sont calculés pour différents types de tumeur, en utilisant des données rapportées en littérature. Il ressort que tous les cancers ont plus ou moins la même sévérité et une valeur moyenne de 11.1 ans de vie perdue par personne affectée est dérivée. Pour les effets non cancérigènes, une classification simplifiée en trois catégories est proposée et une DALYp de 11.1, 1,1 et 0,11 ans de vie perdue par personne affectée est respectivement attribuée à chacune des trois catégories. Finalement, le facteur de pente βED10 et la DALYp pour une substance donnée sont combinés afin de dériver son facteur d'effet. Ce facteur d'effet est exprimé en années de vie perdue par masse absorbée. L'annexe 1.1 résume les facteurs d'effets calculés pour plus de 900 substances toxiques. Les facteurs d'effets pour les effets cancérigènes vont de 1.3·10-9 pour l'anthranilate cinnamylique à 3.4·10-1 [année perdue / mg absorbé] pour la 2,3,7,8-tetrachlorodibenzo-p-dioxine. Les facteurs d'effets pour les effets non cancérigènes vont de 4.2·10-12 pour le 1-Chloro-1,1-difluoroethane à 1.4·10-3 [année perdue / mg absorbé ] pour le béryllium. En chapitre 4, une approche semi-empirique est développée afin d'évaluer le devenir et l'exposition pour des émissions atmosphériques de métaux lourds, de moNOxyde de carbone (CO), de dioxyde de souffre (SO2), d'oxyde d'azote (NOx) et de particules fines. Pour ce faire, le concept d'efficacité d'exposition est utilisé. L'efficacité d'exposition est définie comme le rapport entre la dose absorbée par la population et l'émission induisant cette absorption. Trois types d'efficacité d'exposition sont définis pour une émission atmosphérique mondiale d'une substance donnée. Une efficacité spécifique d'exposition, directement basée sur les concentrations rurales et urbaines inhalées par les hommes, est définie. Une efficacité d'exposition continentale est également définie, en considérant la concentration continentale mondiale pour les régions habitées (les régions marines et désertiques sont exclues). Une efficacité d'exposition globale est définie de façon similaire à partir de la concentration globale mondiale d'une substance. L'efficacité d'exposition est calculée pour les particules fines, le CO, NOx et SO2. L'efficacité d'exposition spécifique présente des valeurs allant de 3.9·10-6 à 2.4·10-5 [mg absorbé /mg émis], indiquant que seulement une très petite fraction d'une émission atmosphérique est inhalée par les humains. L'efficacité d'exposition pour les métaux après inhalation est supposée égale à l'efficacité d'exposition des particules fines, étant donné que les métaux dans l'air sont liés aux particules. Si une déposition atmosphérique sur un sol agricole a lieu, les hommes peuvent être exposés suite à un transfert dans des produits alimentaires. Une première évaluation de ce transfert indique qu'il peut augmenter l'efficacité d'exposition des métaux émis dans l'air d'un facteur 5 à 70. L'efficacité d'exposition spécifique est choisie dans cette thèse pour décrire le devenir et l'exposition des émissions atmosphériques. Elle est supérieure d'un facteur 3 à l'efficacité d'exposition continentale, indiquant que l'utilisation de modèles continentaux à un compartiment tend à sous-estimer l'efficacité d'exposition qui peut avoir lieu dans la réalité. Ceci est dû au fait que des émissions plus élevées ont lieu dans les régions les plus peuplées. Comme première approximation, le facteur 3 pourrait être utilisé comme facteur correctif, afin de dériver l'efficacité d'exposition spécifique à partir de l'efficacité prédite par les modèles continentaux à un compartiment. Dans le chapitre 5, l'efficacité d'exposition déterminée au chapitre 4 et les facteurs d'effet déterminés aux chapitres 2 et 3 sont multipliés afin de déduire les facteurs de dommage sur l'homme (HDF). Ces facteurs de dommage sont exprimés en années de vie perdue par masse émise. En utilisant ces facteurs, l'émission d'une substance peut être convertie en dommage potentiel qu'elle induit sur les humains. Les facteurs de dommage sont calculés pour NOx, SO2, CO et les particules fines, ainsi que pour les métaux émis dans l'air ou dans un sol agricole (voir annexe 1.2 pour le résumé des résultats). Lorsque le transfert dans les produits alimentaires n'est pas considéré, les facteurs de dommage pour les métaux étudiés présentent des valeurs allant de 1.7·10-11 pour chromium(VI) à 1.3·10-8 [année perdue / mg émis] pour le béryllium. Le plomb a le facteur de dommage le plus élevé (1.9·10-8 [année perdue / mg émis]) si le transfert dans des produits alimentaires est considéré. Des facteurs de dommage allant de 2.7·10-10 à 6.6·10-10 [année perdue / mg émis] sont obtenus pour NOx, SO2 et les particules fines, alors que le moNOxyde de carbone est caractérisé par un facteur de dommage 103 inférieur. Par masse émise, les métaux inhalés par les hommes induisent des dommages du même ordre de grandeur que le NOx, SO2 et les particules fines; quand la déposition atmosphérique sur les sols agricoles et le transfert ultérieur dans la nourriture sont considérés, les métaux présentent des facteurs plus élevés. Une validation indirecte des facteurs de dommage est présentée pour le SO2, NOx, CO, les particules fines et quelques métaux, en appliquant leur facteur de dommage à leurs émissions totales ayant lieu en Suisse et en Europe. Les dommages évalués sont plausibles et en accord avec ceux rapportés dans d'autres études. Dans le chapitre 6, une Analyse de Cycle de Vie est entreprise pour comparer cinq scénarios de rinçage des toilettes. Le système d'approvisionnement en eau potable, le système de récupération d'eau pluviale et le système de traitement des eaux usées sont inclus dans les limites de système. Les résultats démontrent que des toilettes économiques (3,5 [l/rinçage]) permettent une réduction significative des besoins en énergie, comparativement à des toilettes conventionnelles (9 [l/ rinçage]). Un approvisionnement conventionnel en eau et une récupération de l'eau pluviale à l'aide d'une citerne de 10 m3 ont des besoins en énergie similaires. Une citerne de stockage de l'eau pluviale de 20 m3, conçue afin d'être complètement indépendant du système d'approvisionnement conventionnel d'eau, est désavantageuse d'un point de vue énergétique. Les pertes calorifiques, liées au réchauffement de l'eau de rinçage dans la maison, ont une contribution significative au besoin en énergie. Les avantages des toilettes économiques sont confirmés en considérant les émissions de l'inventaire. Une première évaluation de l'impact a été exécutée en utilisant la méthode des surface-temps critique (CST95) développée par Jolliet et Crettaz [1997]. Elle indique que le scénario conventionnel utilisant des toilettes économiques (CONVeco) est le plus avantageux, pour toutes les classes d'impact. En appliquant les facteurs de dommage sur l'homme développés dans cette thèse (voir chapitre 5), le scénario conventionnel (CONVeco) a toujours un impact inférieur sur la toxicité humaine comparativement au scénario de récupération (REC10eco). Cependant, les substances ayant l'effet principal sur la santé humaine diffèrent de celles trouvées avec la méthode CST95; les raisons de ce changement sont discutées.
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ABSTRACT: The two-year rodent bioassay represents the golden standard for evaluating the carcinogenicity of chemicals. Because of practical and ethical reasons, alternative approaches have been investigated for many years. Among these approaches, the (quantitative) structure-activity relationships [(Q)SARs] offer promising perspectives for quickly screening a large number of chemicals. To increase the acceptance of (Q)SARs among the regulators, their predictive power needs to be scientifically validated. In this article, we tested the capacity of the DEREKfW expert system to qualitatively predict the rodent carcinogenicity and the genotoxic potential of 60 pesticides recently registered in Switzerland. The percentage of false negatives was found to be 31% for carcinogenicity. The associated sensitivity of 69% indicates that most of the pesticides with positive rodent bioassay results were detected by DEREKfW. On the other hand, the low specificity of 47% indicates that many pesticides may be flagged as carcinogenic while rodent bioassays would not confirm this potential. This may lead to unnecessary testing or the unnecessary restriction of a chemical.
Journal of Chemical Information and Modeling 45(6):1864-73. · 4.68 Impact Factor
