A Time-Dose Response Model to Assess Diuron-Induced Photosynthesis Inhibition in Freshwater Biofilms

Contamination by herbicides is reported in most freshwater environments. These biologically active compounds may impact the non-target biota such as benthic biofilms, at the base of the trophic chain. In agricultural watersheds, herbicides occur as pulses in the system, and traditional dose-response analysis performed at a given duration of exposure (hours to days) may not predict accurately the risk of adverse impacts at shorter temporal scales (minutes to hours) corresponding to pulse exposures. To assess the time-response relationship in biofilms exposed to herbicides, we used diuron, an inhibitor of photosynthesis, to perform bioassays (time-response curves) with the aim of characterizing the initial steps of photosynthesis decrease after exposure to the herbicide (from seconds to hours), for different concentrations of exposure. Diuron-induced inhibition of photosynthesis reflects blockage of electron transfer in PSII, therefore we defined the time lag to reach the threshold of 50% photosynthesis inhibition (t1/2) as the time for diuron to reach its target site (adsorption, distribution). We found a rapid decrease in photosynthetic efficiency: t1/2 values were dose-dependent and ranged from < 30 s (highest concentration of exposure) to 7′20′′ (lowest concentration). While dose-response curves are influenced by the initial biomass or nature of biofilms, time-response curves yielded similar t1/2 for contrasted biofilms, making this parameter a unique response to be valuably incorporated into an ecotoxicology framework. We also assessed the variability of the response as a function of previous short-term (3 h) exposure to diuron. The t1/2 values obtained were consistent with those obtained on non-exposed biofilms, but repeated pulses of diuron exacerbated the decrease in photosynthetic yields. This time-response approach highlighted that diuron reaches its cellular target almost instantaneously (< 1 min), independently of biological parameters (chlorophyll a concentration, adaptation related to exposure history). Reversibility of toxic impacts a few hours after diuron removal was not fully demonstrated, suggesting that the kinetics of diuron release from cells to uncontaminated medium are much slower than binding rates. Our results confirm that repeated exposure is very likely to impair freshwater biofilms, in particular if pulses occur at high frequency

Development of q-PCR approaches to assess water quality: Effects of cadmium on gene expression of the diatom Eolimna minima

This study was undertaken to develop molecular tools to assess water quality using diatoms as the biological model. Molecular approaches were designed following the development of a rapid and easy RNA extraction method suited to diatoms and the sequencing of genes involved in mitochondrial and photosystem metabolism. Secondly the impact of cadmium was evaluated at the genetic level by q-PCR on 9 genes of interest after exposure of Eolimna minima diatom populations cultured in suspension under controlled laboratory conditions. Their growth kinetics and Cd bioaccumulation were followed.Population growth rates revealed the high impact of Cd at 100μg/L with total inhibition of growth. These results are linked to the high bioaccumulation values calculated after 14 days of exposure, 57.0±6.3μg. Cd/g. dw and 734.1±70μg. Cd/g. dw for exposures of 10 and 100μg. Cd/L respectively.Genetic responses revealed the impact of Cd on the mitochondrial metabolism and the chloroplast photosystem of E. minima exposed to 10 and 100μg. Cd/L with induction of cox1, 12S, d1 and psaA after 7 days of exposure for the concentration of 100μg. Cd/L and of nad5, d1 and psaA after 14 days of exposure for both conditions.This is the first reported use of q-PCR for the assessment of toxic pollution on benthic river diatoms. The results obtained presage interesting perspectives, but the techniques developed need to be optimized before the design of new water quality diagnosis tools for use on natural biofilms

An in situ intercomparison exercise on passive samplers for the monitoring of metals, polycyclic aromatic hydrocarbons and pesticides in surface water

An intercomparison exercise on passive samplers (PSs) was organized in summer 2010 for the measurement of selected metals, polycyclic aromatic hydrocarbons (PAHs) and pesticides in surface waters. Various PSs were used and compared at 2 rivers sites and one marine lagoon. A total of 24 laboratories participated. We present selected significant outputs from this exercise, including discussion on quality assurance and quality control for PSs, the interlaboratory variability of field blanks, time weighted average water concentrations and its uncertainties, the representativity of DGT samples, the ability of PSs to lower limits of detection, PAH fingerprints in various PSs compared with spot samples, and the relevance of the permeability reference compounds (PRC) approach for POCIS with pesticides. These in situ intercomparison exercises should enable to progress on the harmonization of practices for the use of passive sampling, especially for priority chemical monitoring and regulatory programs in compliance with the Water Framework Directive (WFD) and Marine Strategy Framework Directive (MSFD)

Pesticide risk assessment and management in a globally changing world—report from a European interdisciplinary workshop

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA [Axe_IRSTEA]DTAM-QT2-ADAPTATION [TR2_IRSTEA]ARCEAU [TR2_IRSTEA]DTAMGlobal climate change will affect worldwide agriculture in many ways. The anticipated or already occurring changes raise concerns about the sustainability of production and the ability of agriculture to feed human populations. This appeals to sustainable agriculture providing ecosystem services more efficiently than today, and accordingly to substantial evolutions of pesticide risk assessment (RA) and risk management (RM). The RA/RM issues were discussed by two European research networks in a 2011 workshop. The RA-RM-monitoring conceptual cycle tends to be virtual, with poor connections between certain steps. The design of more comprehensive emissions scenarios could improve the accuracy of predicted runoff transport, while the microcosm/mesocosm approach could help establish causal relationships between fate / exposure and populations / communities. Combined with ecological modelling, effects can be extrapolated to higher spatial and temporal scales. Risk management of diffuse sources should be designed simultaneously at the watershed and individual plot scales. Monitoring is key to assessing the effectiveness of risk reduction measures reduce and evaluate the overall quality of the aquatic compartment. More flexible monitoring strategies clearly linked to RM decisions are therefore needed. Although some technical questions remain, it is time to apply passive samplers more routinely. A set of research and development needs covering the whole RA/RM cycle is listed in conclusion

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Echantillonnage passif des pesticides polaires : avancées, défis et perspectives pour l'évaluation de l'exposition et du risque écotoxique dans les cours d'eau

Ce mémoire fait la synthèse des travaux menés depuis 2005, sur la thématique de la relation exposition-effets des pesticides polaires sur les organismes aquatiques, dans le cadre de collaborations scientifiques internes ou externes à Irstea, de réseaux et consortium à l’échelle régionale, nationale et internationale, ainsi qu’au travers de la formation par la recherche avec le co-encadrements de stages, de thèses et de post-doctorats. Nous nous sommes notamment intéressés à la mise au point et en ½uvre des techniques d’échantillonnage passif. L’accent a été mis dans un premier temps sur les aspects métrologiques afin de déterminer le domaine d’application (quelles familles de pesticides sont échantillonnées, notamment en lien avec la gamme de polarité et les propriétés physico-chimiques ?) des dispositifs du type "Polar Organic Chemical Integrative Sampler" (POCIS). Le principe de fonctionnement, et donc les performances, de ces outils étant encore peu renseigné dans la littérature, nous avons abordé l’étude des mécanismes et phénomènes diffusifs, ceci afin d’améliorer les modèles cinétiques et la potentielle utilisation quantitative pour mesurer l’exposition dans les milieux. Cela s’est également poursuivi avec le développement de dispositifs novateurs, mieux adaptés pour l’échantillonnage d’herbicides très polaires et ionisables (aryloxyacides, tricétones, sulfonylurées, glyphosate...). Parallèlement aux études visant la compréhension du fonctionnement, conception ou amélioration de tels outils, nous nous sommes intéressés à la représentativité et la pertinence des fractions échantillonnées, notamment en termes potentiel toxique, de biodisponibilité et d’évaluation des effets de mélanges de pesticides à faibles doses environnementales, sur les organismes aquatiques, dont les biofilms de rivière. Enfin, il est également question de la mise en perspective et de l'application à terme des techniques d'échantillonnage passif en complément des réseaux institutionnels (contrôles de surveillance, opérationnel ou d'enquête), soit encore de leur applicabilité dans le cadre de la Directive Cadre sur l'Eau (DCE) et, plus généralement, afin d’améliorer l’évaluation du risque écologique

Application de la DGT pour la quantification du glyphosate et de l’AMPA dans l'eau

Fiche techniqueDans un dispositif DGT, les analytes migrent à travers un gel de diffusion et se fixent de façon iréversible sur la phase réceptrice. Cette fiche méthode donne la marche à suivre pour le déploiement et l'analyse de dispositifs DGT pour quantifier le glyphosate et l'AMPA, deux ligands pouvant se lier à des cations métalliques

Etat de l’art sur l'échantillonnage passif des composés organiques ionisables : développement et applicabilité des techniques POCIS et DGT pour les herbicides acides

Due to their high solubility, their high temporal variations in relation with rapid transfers to surface waters (e.g. case of pesticides, since their mobility increased with the polarity), their punctual and intermittent inputs (e.g. wastewater treatment plant discharges for drug residues), or more generally their concentrations at trace levels (ng.L-1) in aquatic environments, conventional sampling techniques can be insufficient for revealing the occurrence of highly hydrophilic organic compounds. Furthermore, such substances have little or no capacity to bioaccumulate, and it is therefore crucial to get a reliable monitoring of the main compartment/way of exposure (i.e. water column for hydrophilic organic compounds) in an attempt to explain the biological effects and impacts observed in parallel. This report deals with the limitations of the current devices, then the potential solutions and developments of new passive sampling techniques.De par leur caractère fortement soluble, la forte dynamique temporelle liée aux transferts rapides dans les cours d’eau (cas des pesticides dont la mobilité est accrue avec la polarité) ou les apports ponctuels (zones de rejets de stations d’épuration pour les résidus pharmaceutiques), ou bien encore des concentrations à l’état de trace (ng.L-1), les techniques d’échantillonnage classiques peuvent d’avérer insuffisantes pour mettre en évidence la présence de composés organiques très hydrophiles dans des milieux aquatiques. Il est également à noter que de telles substances n’ont pas ou peu tendance à se bioaccumuler, et qu’il est dès lors indispensable de les suivre de façon fiable dans le principal compartiment/voie d’exposition (i.e. colonne d’eau pour les composés organiques hydrophiles) afin de tenter d’expliquer les effets et impacts biologiques observés parallèlement. Ce document fait la synthèse des limitations des dispositifs actuels, puis des pistes et développements possibles de nouvelles techniques d’échantillonnage passif