Ce document synthétise l'ensemble de mes activités de recherche depuis mon doctorat à l'Institut National Agronomique Paris-Grignon (actuellement AgroParisTech), obtenu en 2001, jusqu'à mes travaux les plus récents et en cours effectués au Laboratoire Environnement Eau et Systèmes Urbains (LEESU) où je suis maître de conférences depuis mon recrutement en 2002. Le LEESU est un laboratoire commun à l'Université Paris-Est Créteil Val de Marne (UPEC), l'Ecole des Ponts Paris Tech, l'Université Paris-Est Marne-la-Vallée (UPEMLV) et AgroParisTech. L'ensemble de mes recherches s'inscrit dans un contexte scientifique cohérent puisque mes activités ont toujours traité de la biogéochimie des éléments traces métalliques dans l'environnement. J'ai abordé la problématique des métaux dans les sols pollués durant mon travail de doctorat. Depuis mon recrutement au LEESU, je travaille sur les métaux dans les systèmes aquatiques et, notamment, leurs sources et leur spéciation dans le milieu récepteur. Ce manuscrit comporte classiquement trois parties. En premier lieu, je décris le contexte scientifique correspondant à mes thèmes de recherche. Dans un second temps, j'expose mes différentes activités et les principaux résultats obtenus. Pour finir, je présente mes perspectives de recherche pour les années qui viennent.

The development of real time, label-free biosensors based on ligand-induced nanomechanical responses of microcantilevers (MCs) allows for sensitive and selective detection. High sensitivity is afforded by the MCs small dimensions. Immobilizing biomolecular recognition phases imparts selectivity from bioaffinity interactions. Biological sensors on a MC platform utilize various proteins, such as antibodies and nuclear receptors, which can be used to detect and screen for potential environmental contaminants. The interaction between contaminants and immobilized receptors induces an apparent surface stress that leads to static bending of the MC, which is monitored by an optical beam bending technique. Biofunctionalized MCs can provide high sensitivity and selectivity on a relatively inexpensive platform that requires small amounts of analyte. The goal of this research is to develop and optimize MCs as biosensors to detect low concentrations of contaminants. Initially, the research utilized specific receptors and antibodies to detect and screen for contaminants that are deemed endocrine disrupting chemicals (EDCs). Immobilizing estrogen receptors and specific antibodies on the MC surface may provide information on the ever expanding list of EDCs, along with fundamental endocrine studies. Then, the MC surface was morphologically and chemically optimized. This optimization included the thickness and metal ratio of the dealloyed surface. The concentration, reaction time, and pH of chemical immobilization reagents, which include aminoethanethiol and glutaraldehyde, were optimized by using an anti-body test system. Antibody and protein functionalization conditions, which are incubation time and concentration, were optimized using the anti-immunoglobulin G (anti-IgG) receptor: IgG and an anti-biotin:biotin test systems. The optimized immobilization conditions were applied to the detection of thyroid disrupting chemicals (TDCs) using MCs functionalized with the transport protein thyroxine-binding globulin. The final project involved developing a nanomechanical transducer to study xenobiotic and EDC interactions with the bioreceptor PXR’s ligand binding domain (LBD). The combination of immobilized LBD PXR with a nanostructured microcantilever (MC) platform allows for the study of ligand interaction with the receptor’s binding domain. PXR shows real-time, reversible responses when exposed to specific pharmaceutical, EDC, and xenobiotic ligands. Three binding interactions that involve EDCs are tested, which include phthalic acid, nonylphenol, and bisphenol A, with PXR.

Cave (Petrochelidon fulva) and cliff swallows (Petrochelidon pyrrhonota) were collected along the Rio Grande and evaluated as potential indicators of environmental contamination. The Rio Grande receives toxic substances from agricultural, industrial, municipal, and non-point sources; consequently, high levels of contaminants have been detected in birds, mammals, fishes and sediments. Swallows were obtained from 8 sites between Brownsville and El Paso, as well as from a reference site in Burleson County, 320 miles north of the nearest site of the Rio Grande. Blood samples were analyzed by flow cytometry, a technique that allows the detection of DNA damage in blood and other tissues. Plasma samples were analyzed for thyroid hormones using a radioimmunoassay technique. Organochlorines and trace metal analysis was limited to a few samples. DDE and PCB levels were below levels known to cause reduced hatching, embryo mortality, and deformities, Hg, Pb, and As were below detection, and Se, Ni and Cr concentrations were lower than levels known to cause harm in birds. Neither species showed sex-related differences in chromosome damage. Cave swallows from the Del Rio area had the highest levels of DNA variation, which may be indicative of DNA damage, possibly from PAHs exposure. Previous studies indicate that sediment samples from tributaries near Del Rio have high levels of chromium compared to other sites along the Rio Grande. A significant increase in DNA variation between sampling years was detected in cave swallows from Llano Grande Lake. Wildlife samples collected from Llano Grande Lake have recorded high levels of DDE and PCBs; in addition, this urban/agricultural contaminant sink appears to be affected by PAH exposure. T3 levels were below the detection limit of the radioimmunoassay. There were no gender related differences in T4 levels in cave swallows. Cave swallows sampled from Laredo had significantly higher T4 levels than those from birds at other sites during 1999. It was not possible to determine thyroid hormone disruption in plasma samples. Thyroid hormone and flow cytometry data were useful in establishing baseline data. Areas of concern based on genotoxic data include Llano Grande Lake, Del Rio, and El Paso.

Ecotoxicology studies attempt to evaluate the consequences of exposure to environmental contaminants by defining exposure and effects parameters across multiple levels of biological organization. Genetic markers are well-suited for these studies as they can track both somatic and evolutionary effects. In the studies reported here, connections among contaminant levels in environmental media and biota, in vitro bioassay results, and changes in individual- and population-level biomarkers were explored. Sediment and/or wildlife samples were collected from each of three sites of documented environmental contamination, Sumgayit and Baku in the Republic of Azerbaijan and East Fork Poplar Creek in Tennessee. Sumgayit and Baku are heavily contaminated with petroleum and petrochemical wastes. Sediments from several areas and tissues from turtles inhabiting a contaminated wetland contained high levels of several compounds, including mercury, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides. Sediment extracts produced variable responses in the Salmonella/microsome mutagenicity assay and did not necessarily reflect contaminant burden. Micronucleus counts in European pond turtles were not statistically different from counts in the same species from an uncontaminated reference site. The counts were statistically correlated with tissue levels of mercury, heptachlor, DDD, hexachlorobenzene, and trans-nonachlor. These results confirmed that Sumgayit and Baku are heavily contaminated with a complex mixture of pollutants and demonstrated that genotoxic effects from exposure to contaminated sediments appear to be slight. East Fork Poplar Creek is a stream that receives contaminant influx from a former Department of Energy nuclear weapons production facility and several point and non-point sources around the city of Oak Ridge, Tennessee. In this study, coefficient of variation in cellular DNA content and randomly amplified polymorphic DNA markers were examined in central stonerollers and compared to previous studies in which the same markers were evaluated in red-breasted sunfish from the same sites. While assay responses were attenuated in stonerollers compared to the sunfish, there is some evidence of genetic damage in both species at the most contaminated sampling site. A common problem in the wildlife studies was high within sample variability combined with small sample size, which most likely masked potential contaminant-induced differences in markers used in these studies.

We have developed a regional mass balance model for the St. Lawrence River near Cornwall, Ontario that describes the fate and transport of mercury in three forms, elemental mercury (Hg0), divalent mercury (Hg2+), and methyl mercury (MeHg), in a five compartment environment (air, water, sediments, periphyton, and benthos). Our first objective was to construct a steady-state mass balance model to determine the dominant sources and sinks of mercury in this environment. Our second objective was to construct a dynamic mass balance model to predict and hindcast mercury concentrations in this environment. We compiled mercury concentrations, fluxes, and transformation rates from previous studies completed in this section of the river to develop the model in STELLA®. The inflow of mercury was the major source to this system, accounting for 0.42 mol month-1, or 95.5% of all mercury inputs, whereas outflow was 0.28 mol month-1, or 63.6% of all losses, and sediment deposition was 0.12 mol month-1, or 27.3% of all losses. The dynamic mass balance model provides estimated results that are consistent with measured data and predicts historical local industrial emissions to be approximately 400 kg year-1. Uncertainty estimates were greatest for advective fluxes in surface water, porewater, periphyton, and benthic invertebrates. This model is useful for predicting and hindcasting mercury concentrations in other aquatic environments because it contains the three main environmental compartments, all forms of mercury, and compartments (e.g. periphyton) not included in previous mercury multi-media models.

Estudi de la variació temporal de l'exposició dietètica a contaminants químics en la població de Catalunya. RIBEFOOD, una nova eina per establir els beneficis i riscos de la ingesta d'alimentsRESUM.En els darrers anys, varis estudis han demostrat que alguns aliments poden ser una font potencial d'exposició a contaminants químics.L'objectiu d'aquest treball es determinar les concentracions de PCDD/PCDFs, PCBs, PCNs, PCDEs, PBDEs, HCB i HAP, i l'estimació de la ingesta diària d'aquests contaminants químics per a la població catalana, així com l'avaluació del risc que aquesta ingesta pot suposar per a la salut i la variació temporal respecte a un estudi previ (2000).Amb els resultats, s'ha dissenyat una eina informàtica (RIBEFOOD, la qual determina la ingesta d'una sèrie de macronutrients, micronutrients i contaminats químics presents en 52 aliments d'ampli consum. RIBEFOOD pot ser utilitzat com una eina fàcil per optimitzar els hàbits alimentaris, augmentat la ingesta de nutrients i disminuint la ingesta de contaminants, i en conseqüència els riscos per a la nostra salut. RIBEFOOD és accessible a través de www.fmcs.urv.cat/ribefoodEstudio de la variación temporal de la exposición dietética a contaminantes químicos en la población de Catalunya. RIBEFOOD, una nueva herramienta para establecer los beneficios y riesgos de la ingesta de alimentos. / En los últimos años, varios estudios han demostrado que algunos alimentos pueden ser una fuente potencial de exposición a contaminantes químicos. El objetivo de este trabajo es determinar las concentraciones de PCDD/PCDFs, PCBs, PCNs, PCDEs, PBDEs, HCB y HAP, y la estimación de la ingesta diaria de estos contaminantes químicos por la población catalana, así como la evaluación del riesgo que esta ingesta puede suponer para la salud y la variación temporal respecto a un estudio previo (2000).Con los resultados, se ha diseñado un programa informático (RIBEFOOD), el cual determina la ingesta de una serie de macronutrientes, micronutrientes y contaminantes químicos presentes en 52 alimentos de gran consumo. RIBEFOOD puede ser utilizado como una herramienta fácil para optimizar los hábitos alimentarios, aumentando la ingesta de nutrientes y disminuyendo la ingesta de contaminantes, y en consecuencia los riesgos para nuestra salud. RIBEFOOD es accesible a través de www.fmcs.urv.cat/ribefood

En contrast amb els beneficis per a la salut d'una dieta equilibrada, una qüestió d'interès relacionada amb el consum regular de certs aliments és el risc derivat de l'exposició a potencials substàncies tòxiques, les quals també estan presents en aquests. En els darrers anys, en la majoria d'estudis realitzats a nivell nacional i internacional sobre la ingesta dietètica de contaminats químics, els anàlisis es van realitzar en aliments sense cuinar. En canvi, les qualitats físiques i les qualitats nutricionals d'un cert nombre d'aliments poden ser àmpliament modificades pels processos de cocció. El present estudi dóna una visió global de l'estat actual de la contaminació química en aliments cuinats de major consum a Catalunya. S'han analitzat diferents grups d'aliments així com varies tècniques culinàries. Els contaminants avaluats són: arsènic (As), cadmi (Cd), mercuri (Hg), plom (Pb), dioxines i furans (PCDD/Fs), bifenils policlorats (DL-PCBs), èters difenílics policlorats (PCDEs), èters difenílics polibromats (PBDEs), hexaclorbenzè (HCB), hidrocarburs aromàtics policíclics (HAPs) i compostos perfluorats (PFCs). Potser el resultat més important és que no s'ha trobat cap forma de cuinar que de manera significativa, i per tots els aliments i contaminants avaluats, modifiqui significativament el contingut de contaminants. De tota manera, els resultats de l'estudi poden ser útils com a guia per la selecció de diferents tècniques culinàries per preparar una dieta saludable amb baix contingut de tòxics. / In contrast to the health benefits of a balanced diet, a point of interest related to regular consumption of certain foods is the risk from potential exposure to toxic substances, which are also present in these. In recent years, most studies of national and international dietary intake of contaminated chemicals, the tests were conducted in uncooked foods. However, the physical qualities and nutritional qualities of a number of foods can be largely modified by the processes of cooking. The present study provides an overview of the current state of chemical contamination in cooked foods most consumed in Catalonia. Have analyzed the different food groups as well as various cooking techniques. Contaminants evaluated include: arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb), dioxins and furans (PCDD / Fs), polychlorinated biphenyls (DL-PCBs), polychlorinated diphenyl ethers (PCDEs), ethers polybrominated diphenyl (PBDEs), hexachlorobenzene (HCB), polycyclic aromatic hydrocarbons (PAHs) and perfluorinated compounds (PFCs). Perhaps most important is that the result was not found any way of cooking that significantly and all food and contaminants evaluated, significantly alter the content of pollutants. However, the results of the study can be useful as a guide for the selection of different cooking techniques to prepare a healthy diet with low toxicity.

Georgia State University’s Institute of Public Health along with the Georgia Department of Public Health’s Chemical Hazards Program conducted a needs assessment survey to learn more about the concerns of environmental advocates and other community leaders in Georgia regarding exposure to toxic chemicals. The purpose of the Georgia Environmental Advocacy Groups Health Education Needs Assessment was to better understand community concerns, to identify hazardous waste sites that might warrant some degree of public health evaluation, to find community leaders and personnel interested in assisting the Chemical Hazards Program in implementing public health interventions, to inform the community about the services offered to the public by the Georgia Department of Public Health and to better understand the best methods for distributing health education material. This is the first time the Chemical Hazards Program has conducted an environmental advocacy group leader needs assessment. The results of this pilot study will help the development of future needs assessments conducted by the CHP. Survey development began in August of 2011 and Georgia State University Institutional Review Board approval was granted January 2012. Participants were selected due to their current leadership role of a Georgia environmental advocacy group/organization. Contact information was found for 137 environmental group leaders. Depending on available contact information, potential participants either received the survey through the mail or electronically via email. Surveys were distributed on January 13, 2012 and had to be returned by February 20, 2012. Twenty-one Georgia environmental advocacy group leaders participated in the survey. A majority of participants cited protect/restore natural habitats as the main purpose of their organization, but the survey did reveal 10 environmental groups that focused on protecting human health. Seven of participants that were dedicated to protecting human health expressed interest in working further with the GDPH to develop or implement public health interventions. The survey was also successful in informing participants about the Chemical Hazards Program. Prior to the needs assessment, more than 80% of participants were not aware of the program. Many pertinent suggestions were also made to aid in the development of the brochure aimed at educating community members about the services offered by the CHP. Although a variety of environmental health concerns were cited by the participants, water quality was most often mentioned. More participants reported they were very concerned about drinking water than any other environment. Ninety percent also reported being either concerned or very concerned about contamination in oceans, lakes and streams. A section of the survey also addressed hazards found within the home, unclean drinking water was selected by far the most often as being of greatest concern compared to all other indoor hazards. Many participants listed specific waste or industrial sites that are of concern among members of their community as a source of contaminants. A few contaminated environments were also listed including specific rivers and lakes. Though many did not list specific sources, the majority of participants cited water contamination as being a chemical contamination issue that has the greatest impact on human health. The survey helped reveal specific community concerns regarding potential chemical contaminants and sites that may lead to the CHP conducting public health assessments/consultations and exposure investigations. The survey also revealed the need for general environmental health education and intervention activities based on concerns of the participants as well as the lack of concern by many. The survey was also successful in identifying individuals that may help the CHP gain future partnerships and identifying creative methods for distributing health education material. The CHP plans to follow-up with many of the participants and the survey will be further developed and used to survey other leaders, community members, and public health workers etc. to further investigate the needs and concerns of communities across Georgia.

Ethylene oxide (EO) is a very versatile compound with considerable energy in its ring structure. Its reactions proceed mainly via ring opening and are highly exothermic. Under some conditions, it is known to undergo a variety of reactions, such as isomerization, polymerization, hydrolysis, combustion and decomposition Due to its very reactive characteristic and widely industrial applications, EO has been involved in a number of serious incidents such as Doe Run 1962, Freeport 1974, Deer Park 1988 and Union Carbide Corporation’s Seadrift 1991. The impacts can be severe in terms of death and injury to people, damage to physical property and effects on the environment. For instance, the Union Carbide incident in 1991 caused one fatality and extensive damage to the plant with the property damage of up to 80 million dollars. Contamination has a considerable impact on EO reactivity by accelerating substantially its decomposition and playing a key role on EO incidents. In this work, the reactivity of EO with contaminants such as KOH, NaOH, NH4OH, and EDTA is evaluated. Useful information that is critical to the design and operation of safer chemical plant processes was generated such as safe storage temperatures (onset temperature), maximum temperature, maximum pressure, temperature vs. time, heat and pressure generation rates as a function of temperature and time to maximum rate using adiabatic calorimetry. A special arrangement for the filling-up of the cell was constructed due to the gaseous nature and toxicity of EO. A comparison of their thermal behavior is also presented since several contaminants are studied.

Cave (Petrochelidon fulva) and cliff swallows (Petrochelidon pyrrhonota) were collected along the Rio Grande and evaluated as potential indicators of environmental contamination. The Rio Grande receives toxic substances from agricultural, industrial, municipal, and non-point sources; consequently, high levels of contaminants have been detected in birds, mammals, fishes and sediments. Swallows were obtained from 8 sites between Brownsville and El Paso, as well as from a reference site in Burleson County, 320 miles north of the nearest site of the Rio Grande. Blood samples were analyzed by flow cytometry, a technique that allows the detection of DNA damage in blood and other tissues. Plasma samples were analyzed for thyroid hormones using a radioimmunoassay technique. Organochlorines and trace metal analysis was limited to a few samples. DDE and PCB levels were below levels known to cause reduced hatching, embryo mortality, and deformities, Hg, Pb, and As were below detection, and Se, Ni and Cr concentrations were lower than levels known to cause harm in birds. Neither species showed sex-related differences in chromosome damage. Cave swallows from the Del Rio area had the highest levels of DNA variation, which may be indicative of DNA damage, possibly from PAHs exposure. Previous studies indicate that sediment samples from tributaries near Del Rio have high levels of chromium compared to other sites along the Rio Grande. A significant increase in DNA variation between sampling years was detected in cave swallows from Llano Grande Lake. Wildlife samples collected from Llano Grande Lake have recorded high levels of DDE and PCBs; in addition, this urban/agricultural contaminant sink appears to be affected by PAH exposure. T3 levels were below the detection limit of the radioimmunoassay. There were no gender related differences in T4 levels in cave swallows. Cave swallows sampled from Laredo had significantly higher T4 levels than those from birds at other sites during 1999. It was not possible to determine thyroid hormone disruption in plasma samples. Thyroid hormone and flow cytometry data were useful in establishing baseline data. Areas of concern based on genotoxic data include Llano Grande Lake, Del Rio, and El Paso.