A methodology to determine pesticides pollution sources in water catchments: study case (Belgium).

In the Walloon Region (Belgium), a Committee of Investigation was created in 2007 to investigate and determine the potential pesticides pollution sources in drinkable water catchments. This Committee, constituted by a multidisciplinary team of experts i.e agronomists, soil scientists, phyto-chemists, hydrogeologists, is coordinated by the Walloon Agricultural Research Centre (CRA-W) and funded by the Société Publique de Gestion des Eaux (SPGE). The diagnosis method is inspired of the AQUAPLAINE method (Arvalis, France), and is composed of four steps: 1/preparing the diagnosis using existing data, 2/diagnosis using data bank completed by field observations, 3/meeting and discussion with the pesticide users, 4/final diagnosis and remediation proposal. In a rural district of Walloon Region, a water producer who possesses two catchments ("Les marroniers" (P1) and "Puits N2" (P2)) has problems with pesticides. The pollution started in 1998 with atrazine and bromacile detected in the two catchments. In 2004, 2,6-dichlorobenzamide, metabolite of dichlobenil, was also detected in the catchments. At present, all these pesticides are still found in the catchment P1 and only the 2,6 dichlorobenzamide is found in the other catchment. These active ingredients are not used in agriculture expect atrazine. Indeed, the main user of these products is the public sector. An investigation was realised to locate the main sites which are treated with these pesticides in this commune. The conclusion of this study is that the local authority used dichlobenil, bromacile and atrazine to weed the public areas. In more, the filling and the cleaning areas of sprayer, used for the treatment, are located near the catchments.

CRA-W's committee of intervention: analyse of catchments polluted with pesticides.

In the Walloon Region of Belgium, a committee of intervention has been created to investigate problems of pesticide contamination of various catchments use for drinking water production. This committee involves the Agricultural Research centre--Wallonia (CRA-W, project coordinator) and some University experts. It is funded by the Société Publique de Gestion des Eaux (SPGE). The diagnosis method, base on the AQUAPLAINE method (Arvatis-France), consists of 4 steps. The first step is the preparation of diagnosis (at the office) that takes into account the paper risk of active ingredients. and their uses, the identification of the agricultural parcels, the collection of cartographic and numeric data, the description of the hydrogeological and pedological contexts and the study of the meteorological data in relation with the period of pollution. The second step consists of making a plot diagnosis (on the field) to identify the way of transfer inside the plot and collecting data. At the third step, the people who can apply PPP treatment close to the catchment are met (farmers and city services). Information are collected on treatments applied and on the state of parcels. Based on the hypothesis of pollution cause, the committee proposes solution to solve the problem. One of the catchment that has been investigated by the committee is located at Biesmerée, (Namur province, in Belgium). A temporally contamination was caused by 4 pesticides : chlortoluron, isoproturon, trifluralin and diflufenican. After investigations, it seems that the pollution was probably due to the hydrogeological context. As the river is locally perched over the aquifer, the presence of Poly-aromatic hydrocarbons (PAHs) could be due to the infiltration of surface water inside the catchment or/and to the presence of a sinkhole temporally activated during river flood period. Infiltration rate has to be assessed and river bank impermeabilization is recommended.

Sequence diversity in 36 candidate genes for cardiovascular disorders.

Two strategies involving whole-genome association studies have been proposed for the identification of genes involved in complex diseases. The first one seeks to characterize all common variants of human genes and to test their association with disease. The second one seeks to develop dense maps of single-nucleotide polymorphisms (SNPs) and to detect susceptibility genes through linkage disequilibrium. We performed a molecular screening of the coding and/or flanking regions of 36 candidate genes for cardiovascular diseases. All polymorphisms identified by this screening were further genotyped in 750 subjects of European descent. In the whole set of genes, the lengths explored spanned 53.8 kb in the 5' regions, 68.4 kb in exonic regions, and 13 kb in the 3' regions. The strength of linkage disequilibrium within candidate regions suggests that genomewide maps of SNPs might be efficient ways to identify new disease-susceptibility genes, provided that the maps are sufficiently dense. However, the relatively large number of polymorphisms within coding and regulatory regions of candidate genes raises the possibility that several of them might be functional and that the pattern of genotype-phenotype association might be more complex than initially envisaged, as actually has been observed in some well-characterized genes. These results argue in favor of both genomewide association studies and detailed studies of the overall sequence variation of candidate genes, as complementary approaches.

The Lys198Asn polymorphism in the endothelin-1 gene is associated with blood pressure in overweight people.

There is accumulating evidence that endothelin-1 plays an important role in vascular pathophysiology. Our objective was to examine whether molecular variations at the endothelin-1 locus were involved in susceptibility to myocardial infarction and variation in blood pressure. The entire coding sequence and 1.4 kb of the 5' flanking region were screened. Five polymorphisms were detected, which were genotyped in the ECTIM (Etude Cas-Témoin de l'Infarctus du Myocarde) Study, a multicenter study comparing 648 male patients who had survived a myocardial infarction and 760 population-based controls. The polymorphisms were not associated with myocardial infarction, nor did they contribute to blood pressure levels in the population at large. However, a G/T polymorphism predicting an Lys/Asn change (ET1/C198) strongly interacted (P<0.001) with body mass index in the determination of blood pressure levels. There was a steeper increase of blood pressure with body mass index in carriers of the T allele than in GG homozygotes. As a consequence, the T allele was associated with an increase of blood pressure in overweight subjects (body mass index >/=26 kg/m2), while no significant effect was observed in lean subjects (body mass index <26 kg/m2). To determine whether this finding could be replicated, the ET1/C198 was genotyped in the Glasgow Heart Scan Study, a population-based study including 619 men and 663 women. Subjects homozygous for the T allele had higher resting blood pressure levels than others (P<0.05). A similar interaction between the T allele and body mass index was observed on the maximum blood pressure achieved during a treadmill exercise test (P<0.001). In conclusion, results from 2 independent studies suggest that the ET1/C198 polymorphism is associated with blood pressure levels in overweight people.