Perturbateur endocrinien | EPFL Graph Search

vignette|Comparaison de la structure moléculaire de l'estradiol (à gauche) avec celle d'un perturbateur endocrinien xénoestrogène (à droite) Un perturbateur endocrinien (PE, ou aussi « leurre hormonal », « xénohormone », « disrupteur endocrinien ») est une molécule ou un agent chimique composé, xénobiotique ayant des propriétés hormono-mimétiques et décrit comme cause d'anomalies physiologiques, et notamment reproductives. L'expression a été créée en 1991 par Theo Colborn . Ces molécules agissent sur l'équilibre hormonal de nombreuses espèces sauvages ou domestiques (animales ou végétales dans le cas des phytohormones). Elles sont souvent susceptibles d'avoir des effets indésirables sur la santé en altérant des fonctions telles que la croissance, le développement, le comportement et l'humeur, la production, l'utilisation et le stockage de l'énergie, la fonction de repos (le sommeil), l'hémodynamique et la circulation sanguine, ainsi que la fonction sexuelle et reproductrice. Ef

Helio-photocatalytic enhancement of the biodegradation of biorecalcitrant pollutants in water

Simeon Kenfack

The importance of the photocatalytic treatment of water is continuously growing since the 80s. In spite of the well management of the existing biological water treatment plants and the constant reinforcement of the wastewater discharge standards, the development of new water depolluting processes among which the photocatalysis is still relevant. It is recognized that certain chemicals mostly from the synthetic chemistry are not or could only be biodegradable under very critical conditions. When these "biorecalcitrant" pollutants are rejected in a biological wastewater treatment plant, they very often cross it without being degraded and thus, they accumulate in the environment and/or in the living beings. Some of them like the phthalates and the pesticides are known for their carcinogenic and mutagen effects or, they induce hormonal disruptions in the animals, including humans. In general, all the Advanced Oxidation Processes (AOP) whose characteristic is to generate hydroxyls radicals (OH) are able to degrade most of the organic molecules including the biorecalcitrant chemicals. As a technology using the photons emitted by a light source to excite a catalyst and facilitate the generation of the 'OH radicals, the photocatalysis would be a more environmental compatible and less expensive process for depolluting such chemicals, if the light source is natural: the sun. For the first time, a study of potential application in the field of helio- photocatalysis was explored in a sub-Saharan Africa country (Burkina Faso), making profitable the significant solar radiation present in that country, to validate certain results obtained using appropriated experimental and analytical methods at the Laboratory for Environmental Biotechnology (LBE) at the Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland. The main objective of this thesis was to contribute to evaluate some physicochemical and technical rules which guide the scaling up processing of the helio-photo-Fenton process. To achieve this, the work was organized in several phases of laboratory work at the EPFL and field apply work at the Ecole Inter-Etats d'Ingénieurs de l'Equipement Rural (EIER) of Ouagadougou in Burkina Faso. To mitigate the deficit of sophisticated analytical material during the field work's periods, a simple analytical method requiring relatively modest equipment was developed and validated in the laboratory and on the field. This thesis is organized in 5 chapters of which the first focuses on the problems of this research and presents the fundamental principles of the photocatalytic processes. Chapter 2 presents the systematic development of a low cost analytical method built up and validated in the laboratory for field's applied studies on three phthalates: the dimethyl phthalate (DMP), the diethyl phthalate (DEP) and the Diallyl phthalate (DAP). The chapter 3 focuses on the study of the optimal parameters influencing the helio-photodegradation of the DEP. In the chapter 4, two case studies on the enhancement of the biodegradability of some biorecalcitrants wastewaters of which, the first evaluates the possibility of integrating the photocatalysis into a global strategy of managing the effluents of a chemical industry and the other treat problem of the depollution of the water polluted by a pesticide are presented. The last chapter presents some modelling approaches allowing to evaluate the solar UVA energy (needed for the helio-photocatalysis) basing on the equation of the solar UVA irradiation which was proposed and tested with the one year solar data of Ouagadougou.

EPFL2006

Assessment of occupational exposure to pesticides with multi-class pesticide residues analysis in human hairs using a modified QuEChERS extraction method, case study of gardening areas in Burkina Faso

Luiz Felippe De Alencastro, Edouard René Gilbert Lehmann, Jean-Jacques Stéphane Nfon Dibie, Christelle Oltramare

Pesticides have been proved to potentially cause multiple adverse health effects. The present study is part of a global project focusing on pesticides impacts on the environment and human health in gardening in Burkina Faso. In absence of existing monitoring, the present study aims at proposing a comprehensive indicator of occupational exposure to 48 pesticides identified during field campaigns. As a noninvasive and safe indicator of long term exposure, increasing interest is being observed in hair analysis for biomonitoring of human exposure to pesticides. In order to dissociate occupational and environmental exposure in the study area, two study populations have been randomly selected: fifty gardeners (operators) and fifty non users (reference population). The Ethics Committee of the Burkina Faso approved this study and written informed consent was obtained from all donors. Multiresidue extraction procedure using a modified QuEChERS extraction method has been developed and applied to the collected samples. Briefly, hairs were cut on the posterior of the head, subsequently cut in small pieces and spiked with appropriate 13C- or deuterated surrogates. After overnight incubation, they were extracted in acetonitrile, cleaned-up by Dispersive SPE (dSPE), concentrated and separated prior analysis on GC-MS and LC-MS/MS. Each sample was accompanied by a questionnaire on hair care practices. Different incubation, extraction methods and dSPE sorbents have been tested (temperature, type, volume, etc.). The best method was found to be a modified AOAC 2007.01 QuEChERS procedure, including 12h incubation at 37°C followed by dSPE clean-up with Supelco Z-sep/C18® sorbent. The substances detected in collected samples include pesticides commonly used in the study area such as acetamiprid, imidacloprid, cypermethrin, profenofos but also dieldrin a banned persistent organochlorine. These pesticides were detected in hairs of the gardeners but also in the samples of the reference population indicating the occurrence of passive contamination. This study presents a comprehensive assessment of sample preparation, extraction and clean-up procedure for multi-class pesticide residues analysis in human hairs. The modified QuEChERS extraction procedure proposed offers a simple and robust tool suitable to developing countries for monitoring human exposure and evaluation of compliance with policies. The study design, including comparison between reference and operators populations allowed to dissociate the influence of environmental exposure and direct occupational exposure. Results indicate that potential carcinogen, endocrine disruptor, neurotoxic and persistent pesticides have been detected in collected hairs.

2016

Assessment of human exposure to pesticides by hair analysis: The case of vegetable-producing areas in Burkina Faso

Luiz Felippe De Alencastro, Edouard René Gilbert Lehmann, Jean-Jacques Stéphane Nfon Dibie, Christelle Oltramare

The present work assesses human exposure to pesticides in vegetable-producing areas in Burkina Faso, using hair as an indicator. The study design includes a comparison between operators who are occupationally exposed while working in the fields and a reference population (i.e. not occupationally exposed) to evaluate both oc- cupational and indirect exposures. Hair samples from volunteers (n = 101) were positive for 17 pesticides (38 analyzed). Acetamiprid, desethylatrazine, carbofuran, and deltamethrin were detected for the first time in field samples. With a maximum of 9 residues per sample, pesticide exposure was ubiquitous in both populations. Contamination by acetamiprid, cypermethrin, and lambda-cyhalothrin (used in vegetable production) prevailed in operator samples. For other pesticides, such as imidacloprid and deltamethrin, no significant difference was found. This indicates a potentially large environmental exposure (dietary intake or atmospheric contamination) or the prevalence of other contamination sources. The present findings are concerning, as detected levels are globally higher than those previously reported, and indicate exposure to endocrine disrupting chemicals and probable carcinogens. Hair was found to be a suitable matrix for biomonitoring human exposure to pesticides and assessing dominant factors (i.e. sex, age, and protective equipment) in subgroups, as well as identifying geographical contamination patterns.

2018

Helio-photocatalytic enhancement of the biodegradation of biorecalcitrant pollutants in water

Simeon Kenfack

EPFL2006

Luiz Felippe De Alencastro, Edouard René Gilbert Lehmann, Jean-Jacques Stéphane Nfon Dibie, Christelle Oltramare

2016