Diagnosis and Management of Field Pollution in the Case of an Organochlorine Pesticide, the Chlordecone

International audienc

A conceptual model of organochlorine fate from a combined analysis of spatial and mid- to long-term trends of surface and ground water contamination in tropical areas (FWI)

In this study, we investigated the management of long-term environmental pollution by organic pollutants such as organochlorine pesticides. We set out to identify conditions that are conducive to reducing pollution levels for these persistent molecules and then propose a conceptual model of organochlorine fate in water. Our approach looked at spatio-temporal changes in pollutant contents in surface water (SW) and groundwater (GW) on a large scale, in order to decipher the respective roles of soil, geology, hydrology and past treatment practices. The case of chlordecone (CLD) on the island of Martinique (1100&thinsp;km2) was selected given the sampling campaigns carried out since 2007 over more than 150 sites. CLD, its metabolite chlordecone-5b-hydro (5bCLD) and the metabolite-to-parent-compound ratio were compared. As regards the spatial variability of water contamination, our results showed that banana cropping areas explained the location of contaminated SW and GW, whereas the combination of soil and geology factors explained the main spatial variability in the 5bCLD∕CLD ratio. For temporal variability, these conditions defined a high diversity of situations in terms of the duration of pollution, highlighting two groups: water draining old geological formations and ferralsols or vertisols vs. recent geology and andosols. A conceptual leaching model provided some key information to help interpret downward trends in CLD and 5bCLD observed in water. Lastly, a conceptual model of organochlorine fate is proposed to explain the diversity of the 5bCLD∕CLD ratio in water. Our conclusions highlight the combined role of soil and groundwater residence time for differentiating between conditions that are more conducive, or not, to the disappearance of CLD from the environment. This paper presents a model that provides an overall perception of organochlorine pesticide fate in the environment.</p

Phytotherapeutic and naturopathic adjuvant therapies in otorhinolaryngology

Phytotherapeutic pharmaceuticals and herbal medicinal products with its roots in classical phytotherapeutic medicine have a well-established role in otolaryngological therapy, especially for diseases of the upper airways and acute and chronic infections. A thorough selection and application could mean huge benefit for the patient, in particular in cases with contraindications, chemo- and antibiotic resistance or patient request. Besides, it might spare other medications. Phytotherapeutic pharmaceuticals must fulfil the same criteria of quality, effectiveness and harmlessness of evidence-based medicine like chemical pharmaceuticals, although they are often prescribed due to its well established or traditional based use. This review focuses on phytotherapeutic therapies well established within the European Community for otolaryngologic disease patterns by referring to clinical studies or meta-analysis

Chlordecone retention in the fractal structure of volcanic clay

Chlordecone (CHLD), a soil and foodstuff pollutant, as well as an environmentally persistent organochlorine insecticide, was used intensively in banana fields. The chlordecone uptake of three crops was measured for two types of polluted soils: allophanic and non-allophanic. The uptake is lower for allophanic soils even if their chlordecone content is higher than with non-allophanic soils. The fractal structure of the allophane aggregates was characterized at the nanoscale by small angle X-rays scattering, pore size distribution and transmission electron microscopy. We showed that clay microstructures should be an important physico-chemical factor governing the fate of chlordecone in the environment. Allophanic clays result in two counterintuitive findings: higher contaminant trappings yet lower contaminant availability. We propose that this specific, tortuous structure, along with its associated low accessibility, partly explains the low availability of chlordecone confined in allophanic soils. Capsule The fractal and tortuous microstructure of allophane clay favours the chlordecone retention in soils and disfavours the crop uptake

Natural nano materials trapp pollutants in soils

Persistent pesticides led to long term pollution of soils and consequently contaminate rivers, groundwater, ecosystems and finally human beings. Volcanic soils (andosols) are generally more polluted than the other kinds of tropical soils but data show that andosols release less pesticides to percolating water and crops. Andosols contain amorphous clays (allophane) which present unique structures and physical properties compared to crystalline clays. Allophane aggregates have physical features very close to that of nano porous materials like synthetic gels: large pore volume and water content, a broad pore size distribution, a high specific surface area and a fractal structure. The aim of the study was to show the influence of the features (nano materials structure, shrinkage during drying) of these natural gels on the pesticide retention. Our study confirms that the soil to crop pesticide transfer is lower in andosols compared to other volcanic soils. Associated to high organic matter content, the allophane microstructure favor pollutants (chlordecone) accumulation in soils. We put forth the importance of the nano porous features of allophane (the associated tortuous microstructure) but also the pore collapse during drying, for pollutant trapping in soils

Crisis Management of Chronic Pollution: Contaminated Soil and Human Health

International audienceno abstrac

Effects of an extract of Ginkgo Biloba on noradrenergic systems of rat cerebral cortex

Oral treatment of rats withGinkgo biloba extract (Gb) elicited a biphasic effect on normetanephrine (NMN) content of cerebral cortex; an initial decrease was evident after 45 minutes, followed by a marked increase that was evident after 14 days. Chronic treatment with Gb led to decreases in the density of3H -dihydroalprenolol binding (after 27 days or 2 months) and in isoproterenol-stimulated adenylate cyclase activity (after 2 months) of the cerebral cortex. Taken together, these results indicate that the effects of Gb on the central β-adrenergic system might be involved in its therapeutic actions. © 1985 The Italian Pharmacological Society

Crop protection and environmental health : legacy management and new concepts

Chlordecone, an organochlorine insecticide, pollutes soils and contaminates crops and water resources and is biomagnified by food chains. As chlordecone is partly trapped in the soil, one possible alternative to decontamination may be to increase its containment in the soil, thereby reducing its diffusion into the environment. Containing the pesticide in the soil could be achieved by adding compost because the pollutant has an affinity for organic matter. We hypothesized that adding compost would also change soil porosity, as well as transport and containment of the pesticide. We measured the pore features and studied the nanoscale structure to assess the effect of adding compost on soil microstructure. We simulated changes in the transport properties (hydraulic conductivity and diffusion) associated with changes in porosity. During compost incubation, the clay microstructure collapsed due to capillary stresses. Simulated data showed that the hydraulic conductivity and diffusion coefficient were reduced by 95 and 70 % in the clay microstructure, respectively. Reduced transport properties affected pesticide mobility and thus helped reduce its transfer from the soil to water and to the crop. We propose that the containment effect is due not only to the high affinity of chlordecone for soil organic matter but also to a trapping mechanism in the soil porosity

Field validation of chlordecone soil sequestration by organic matter addition

Purpose The use of chlordecone (CLD) has caused pollution of soils, which are now a source of contamination for crops and ecosystems. Because of its long-term impacts on human health, exposure to CLD is a public health concern and contamination of crops by CLD must be limited. To this end, we conducted field trials on chlordecone sequestration in soil with added compost. Materials and methods The impact of added compost on chlordecone sequestration was measured in nitisols. After characterization of the soil, the transfer of chlordecone from soil to water was assessed in a leaching experiment and from soil to two crop plants in a nitisol plot. Finally, to understand the underlying processes, changes in CLD content were measured in soil fractions and soil porous properties were assessed after the addition of compost. Results and discussion A rapid seven-fold decrease in water extractable CLD was observed in amended soils. Five percent amendment led to a significant reduction in the contamination of crops by CLD; edible radish tubers were 50% more contaminated without added compost and cucumber fruits were 60% more contaminated. After the addition of compost, CLD content increased in the fraction of pre-humified or partially mineralized organic debris. Finally, in contrast to andosols, adding compost to nitisols did not affect the soil microstructure. Conclusions Increasing chlordecone sequestration by adding compost could be an alternative solution until soil decontamination techniques become available. This could be a provisional way to control further release of CLD from contaminated soils towards other environmental compartments

Soil microstructure and organic matter : keys for chlordecone sequestration

Past applications of chlordecone, a persistent organochlorine pesticide, have resulted in diffuse pollutionof agricultural soils, and these have become sources of contamination of cultivated crops as well as ter-restrial and marine ecosystems. Chlordecone is a very stable and recalcitrant molecule, mainly presentin the solid phase, and has a strong affinity for organic matter. To prevent consumer and ecosystemexposure, factors that influence chlordecone migration in the environment need to be evaluated. In thisstudy, we measured the impact of incorporating compost on chlordecone sequestration in andosols asa possible way to reduce plant contamination. We first characterized the transfer of chlordecone fromsoil to plants (radish, cucumber, and lettuce). Two months after incorporation of the compost, soil-planttransfers were reduced by a factor of 1.9-15 depending on the crop. Our results showed that addingcompost modified the fractal microstructure of allophane clays thus favoring chlordecone retention inandosols. The complex structure of allophane and the associated low accessibility are important charac-teristics governing the fate of chlordecone. These results support our proposal for an alternative strategythat is quite the opposite of total soil decontamination: chlordecone sequestration. (Résumé d'auteur