Factors promoting the exposure to bioaerosols among crop workers

Introduction. Agricultural workers are among the professional groups most at risk of developing acute or chronic respiratory problems. Despite this fact, the etiology of these occupational diseases is poorly known, even in important sectors of agriculture such as the crops sector. Cereals can be colonized by a large number of fungal species throughout the plants' growth, but also during grain storage. Some of these fungi deliver toxins that can have a serious impact on human health when they are ingested via wheat products. Although International and European legislation on contaminants in food, including mycotoxins, include measures to ensure protection of public health by setting down the maximum levels for certain contaminants, the risks associated with the inhalation of such molecules during grain handling remains poorly documented. Goal of study. This project's objective was to characterize worker exposure to pathogenic, irritative or allergenic microorganisms and to identify the abiotic or biotic factors that reduce the growth of these microorganisms in crops. Indeed, the proliferation of microorganisms on wheat is dependent on temperature, rainfall and human disturbance (e.g. usage of tillage, addition of fungicides). A change in the concentration of these microorganisms in the substrate will directly result in a change in the concentration of aerosolized particles of the same microorganisms. Therefore, the exposure of worker to bioaérosols will also change. The Vaud region of Switzerland is a perfect region for conduct such a project as weather conditions vary and agricultural land management programs are divers at a small geographic scale. Methods. Bioaerosols and wheat dust have been sampled during wheat harvesting of summer 2010 at 100 sites uniformly distributed in the Vaud region that are representative of the different agriculture practices. Personal exposure has been evaluated for different wheat related activities: harvesting, grain unload, baling straw, the cleaning of harvesters and silos. Aerosols have been sampled at a rate of 2L/min between 15 min to 4 hours (t) on a 5m PVC filter for estimating the total dust inhaled, on gelatine filter for the identification and quantification of molds, and on a 0.45um polycarbonate filter for endotoxin quantification. Altitude, temperature and annual average rainfall were considered for each site. The physical and chemical characteristics of soils were determined using the methods in effect at Sol Council (Nyon). Total dust has been quantified following NIOSH 0500 method. Reactive endotoxine activity has been determined with Limulus Amebocyte Lysate Assay. All molds have been identified by the pyrosequencing of ITS2 amplicons generated from bioaerosol or wheat dust genomic DNA. Results & Conclusions. Our results confirm the previous quantitative data on the worker exposure to wheat dust. In addition, they show that crop workers are systematically exposed to complex mixtures of allergens, irritants or cytotoxic components. The novelty of our study is the systematic detection of molds such as Fusarium - that is a mycotoxins producer - in the bioaerosols. The results are interpreted by taking in account the agriculture practice, the Phosphorus : Carbon : Nitrogen ratio of the soil, the altitude and the average of rainy days per year.

Factors promoting the exposure to bioaerosols among crop workers

Agricultural workers are among the professional groups most at risk of developing acute or chronic respiratory problems. Despite this fact, the etiology of these occupational diseases is poorly known, even in important sectors of agriculture such as the crops sector. A chronic exposure to multiple microorganisms, such as different bacterial and fungal species, has been proposed to be the cause of these multiple respiratory pathologies. Nevertheless, these microbial communities are still partially known. The aim of this study is to characterize all fungal species inhaled by the crops workers during different grain related activities and identify the abiotic and biotic factors that reduce the growth of the toxigenic, irritative or allergenic microbial species. Here, we are presenting the factors promoting the exposure to bioaerosols during different wheat related activities: harvesting, grain unload, baling straw, the cleaning of harvesters and silos. Total dust has been quantified following NIOSH 0500 method. Reactive endotoxin activity has been determined with Limulus Amebocyte Lysate Assay. All molds have been identified by the pyrosequencing of ITS2 amplicons generated from bioaerosol.

Characterizing variation in mycorrhiza effect among diverse plant varieties.

Exploitation of arbuscular mycorrhizal fungi may be an important approach for development of reduced-input agriculture. We discuss the use of linear models to analyze variation in mycorrhiza response among diverse plant varieties in order to assess the value of mycorrhizas. Our approach allows elimination of variation linked to differences in plant performance in the absence of mycorrhizas and the selection of plant lines that might harbor genetic variation of use to improve the mycorrhizal symbiosis in agriculture. We illustrate our approach by applying it to previously published and to novel data. We suggest that in dealing with a relative trait such as mycorrhiza effect, the choice of measure used to quantify the trait greatly affects interpretation. In the plant populations under consideration, we find evidence for a greater potential to increase mycorrhiza benefit than previously suggested.

L'équité d'accès aux ressources en eau : fin ou moyen d'amélioration de l'efficacité de l'irrigation ? : la gestion des ressources en eau dans l'état du Gujarat (Inde) dans la perpective de la political ecology

La thèse présentée ici est le résultat d'une étroite collaboration avec une ONG indienne, AKRSP(I), intervenant dans le développement de l'irrigation au Gujarat depuis plus de 25 ans. Un SIG prototype a été mis en oeuvre et nous permet de proposer ime analyse spatiale et quantitative de l'action de cette ONG ainsi qu'une réflexion plus générale sur les leviers de mise en valeur et de gestion des ressources en eau à des fins agricoles. On peut souligner trois principaux enseignements: Les perspectives d'application des SIG au sein des ONG sont manifestes. Les exigences des bailleurs de fonds peuvent néanmoins faire obstacle à leur développement car, indi-rectement, ils favorisent la mise en oeuvre de SI voués à la justification plutôt qu'à la planification et au suivi des programmes d'actions. Ce résultat soulève la question de la pertinence de l'encadrement, des critères d'évaluation et de la conditionnalité de l'aide publique au développement. Les ONG ont un fort potentiel pour participer à la mise en valeur des ressources en eau en Inde et aider à relever le défi agro-démographique indien, en particulier dans les zones marginales où les services étatiques sont en retrait. Les stratégies d'action basées principalement sur l'application des instruments économiques et techniques doivent cependant être modifiées. Nous montrons qu'elles favorisent une inégalité d'accès aux ressources qui débouche sur une efficacité limitée des pratiques d'irrigation, sur un plan agro-technique. Ces résultats soulignent la nécessité de poursuivre une réflexion critique des discours et solutions dominants en matière de gestion des ressources en eau. Deux pistes d'amélioration sont avancées: 1. considérer l'équité d'accès comme un moyen d'optimiser la gestion de la ressource (limiter le volume d'eau par agriculteur pour encourager les choix de cultures irriguées peu consommatrices et l'adoption des technologies d'économie d'eau), 2. prêter attention à l'ordre dans lequel les différents instruments de gestion disponibles sont employés afin de les articuler dans un séquençage temporel pertinent. La Political Ecology apparait comme un cadre conceptuel très pertinent pour engager cette réflexion critique. Elle permet d'intégrer différentes échelles d'asymétries de pouvoirs à la compréhension des situations et des blocages observables localement : inégalités de capabilités et forces socio-politiques à l'échelle locale, politiques agro-industrielles (coton) et jeux d'alliances politiques des castes à l'échelle nationale, discours et conflits idéologiques ou orientations stratégiques des bailleurs de fonds à l'échelle internationale... Notre recherche empirique contribue modestement au développement de cette Political Ecology de la mise en valeur et de la gestion des ressources en eau. - The present research is based on a close collaboration with an indian NGO, AKRSP(I), which is active in the development of irrigation facilities in Gujarat for the past 25 years. We built a GIS prototype providing quantitative and spatial datas to analyse the NGO intervention and propose a general reflection about water resources development and management issues. Three main findings may be emphasized : The potential of GIS within the workings of an NGO is obvious, as an information ma-nagement tool as much as for developing analytical capacity. However, financial backers expectations may not favour a relevant development of this technology. Indirectly, they promote Information Systems built to justify rather than to plan or monitor action pro¬grammes. This raises the question of stricter framework, conditionality criters and stan¬dardised assessment indicators surrounding official development assistance. There is strong potential that NGOs can assist with the improvement of water resources in India. They can help in overcoming Indian demographic-related agricultural challenges, especially in marginal rural areas neglected by state services. However, intervention strategies mainly based on technical and economic management tools has to be adapted. We found that they lead to inequitable access and distribution of water resources what induces a low efficiency of irrigation practices from an agro-technical point of view. These results underline the need to go further in criticizing dominant ideas and guidelines regarding water resources management. We suggest two other options : 1. to consider equitable access has a tool to improve the effective use of water for agricul¬tural purposes (limiting the volume of water available per farmer would encourage them to adopt low water consumption crops and water saving technics), 2. to consider more carefully the order of use of the various management tools available and to structure them in a relevant sequence. Here, Political Ecology seems to be a relevant conceptual framework to enter into such a critical reflection, integrating different levels and scales of political asymmetries at the core of environmental issues. Indeed, the understanding of regional water situations and social stumbling blocks needs not only to consider local capabilities and socio-political inequities, but also agro-industrial policy (e.i. cotton) and caste political alliances at a national scale, as well as ideological and narrative struggles or strategical orientations of financial backers at an international level. Our empirical research modestly contributes to the development of such a Political Ecology of water resources development and management.