Pesticide | EPFL Graph Search

Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampricide. The most common of these are herbicides, which account for approximately 50% of all pesticide use globally. Most pesticides are intended to serve as plant protection products (also known as crop protection products), which in general, protect plants from weeds, fungi, or insects. As an example, the fungus Alternaria solani is used to combat the aquatic weed Salvinia. In general, a pesticide is a chemical (such as carbamate) or biological agent (such as a virus, bacterium, or fungus) that deters, incapacitates, kills, or otherwise discourages pests. Target pests can include insects, plant pathogens, weeds, molluscs, birds, mammals, fish, nematodes (roundworms), and microbes that destroy property, cause nuisance, or spread disease, or are dise

Analyse des pesticides dans les cheveux: une nouvelle approche pour l’évaluation de l’exposition professionnelle

Christelle Oltramare

pesticides. A high number of pesticides are known as endocrine disrupting chemicals or having a supposed or verified carcinogenic effect. These toxic compounds are found in the environment, in water or in food. Once in our organism these molecules can be metabolised or stored. GOALS. In order to measure the impact on human health of gardening activity in Burkina Faso, hair analysis will provide information on the pesticides’ exposition of operators. The evaluation of pesticides exposure risks for human health is usually over estimated when there is only the analysis of environmental matrices (air, water, soil…) As the aim of this project is to understand the impact of gardening activity, the volunteers who participate in this project will be classified into two groups. First, the exposed population considers the operators. Then, the reference population regroups people living in the same area that the population studied, but without being in direct contact with pesticides. This population will be our baseline. In this way, contaminations due to other vectors such as food, water, vector control etc. will not be considered to evaluate the exposition due to gardening. An inovative protocole. The protocol developed, optimised and used for natural samples is inspired from the existing method QuEChERS AOAC 2007.01. This method is used to analyse pesticides in fruits, vegetables or soils samples. The main principle is simple and based on the salting-out effect. Hair pesticides residue analysis are made in GC/MS and LC/MS-MS. REsults. Analysis over 73 volunteers shows a 100% contamination of imidaclorprid in hair. The professional activity impact is observable on the acetamiprid concentration (10 times more in gardener’s population than in the reference population). The exposed population has a mean sum of 2469.3 ng pesticides/ g hair whereas the reference population has a mean sum of 1709.5 ng pesticides/g of hair.

2016

Regional and local scale pesticide transport in the alluvial plain of the Swiss Rhône River Valley

Kirsten Meiwirth

The herbicide transport and the groundwater vulnerability to pesticide contamination were studied in the alluvial aquifer of the Rhône River Valley near Martigny (Southwest Switzerland). The low clay and organic matter content of the soil, the intensive agricultural use, and the low depth of the groundwater table, lead to an alleged high vulnerability of the groundwater to contamination. Groundwater is used for irrigation, drinking water supply, and industrial purposes; it is of great economic and ecological importance which makes it particularly interesting to study. The work consists of local scale transport experiments and a regional monitoring of the groundwater over a two year period. At the local scale, two herbicides (atrazine and isoproturon) and a tracer were applied to instrumented field plots (4 m2) in two consecutive years and the transport through the vadose zone was studied in detail. Water flow and solute transport are closely linked to climatic factors. After the application, the pesticides remain at the soil surface as long as no precipitation occurs. Following to the first heavy rainfall, the chemicals are quickly transported through the vadose zone and part of them reaches the groundwater in a short time. During dry periods, the concentrations decrease steadily in the soil profile and the groundwater. After further rainfall, additional concentration peaks are observed in the groundwater, while only small peaks appear near the soil surface. Approximately 2.5 months after the application, the chemical concentration in the soil and in the groundwater has decreased considerably. The experimental results have been used to evaluate a mechanistic deterministic root zone model (HYDRUS-1D). The aim of the simulations was to define the processes involved in pesticide transport and, if possible, to predict the fate of chemicals applied at the soil surface. The MIM (mobile-immobile water) concept was used in order to account for the rapidity of the observed transport. In the study area, the shallow groundwater influences considerably the water conditions in the unsaturated zone; apparently, in such cases the use of a one-dimensional model to simulate the water flow and the chemical transport in the vadose zone is hindered due to difficulties in defining the lower boundary condition. Groundwater flow is typically three-dimensional and therefore, a global (saturated - unsaturated) 3-D model or the coupling of an unsaturated 1-D model to a 3-D saturated model would be more appropriate. Nevertheless, HYDRUS-1D allowed to describe qualitatively the observed results and to confirm the assumption that accelerated flow occurs on the experimental plots. At the regional scale, 13 piezometers were installed in an observation area (400 ha), and the groundwater was regularly analysed for the concentration of 6 herbicides (atrazine, terbutylazine, simazine, deethylatrazine, isoproturon, and diuron). Herbicides were detected in 12 piezometers, sometimes at high concentrations, but during a short period of time (mid May to mid July). Throughout the rest of the year, the concentrations remained below the drinking water limit. The observations are in good agreement with the conclusions of the local experiments (rapid transport, important influence of the climatic conditions, quick decrease of concentration peaks). Furthermore, the groundwater characteristics play an important role for the observation of herbicides. Near the Rhône river, high hydraulic gradients quickly dilute chemicals leaching from the fields above and herbicides coming from more distant fields may also be observed. Near the slope, an inflow of contaminated water from the hill side (vineyards) contributes to the groundwater contamination. Within the plain, high concentrations of herbicides applied to an above located field can temporarily be observed. Contaminations are confined in time and space and different substances are detected from one piezometer to another. This lack of continuity in pesticide concentrations will complicate the prediction of the solutes' fate in the groundwater, and a very precise knowledge of the pesticides use, both in space and time, is required.

EPFL2003

A strategy for xenobiotic removal using photocatalytic treatment, microbial degradation or integrated photocatalytic-biological process

Miléna Lapertot

According to the limited natural resources and due to the risks of anthropogenic pollution, it appears necessary to react efficiently in order to remove existing contaminations and avoid the creation of new ones. Therefore, the purpose of this thesis is to propose a sustainable strategy for treating problematic pollutants with the most adequate process. First, an overview of the different treatment processes has been given. In particular, biological, photocatalytic and integrated biological-photocatalytic treatments have been described as efficient methods to remove xenobiotics. Biological treatment of contaminated environments and industrial effluents has been presented as the most attractive method on a cost-benefit extent. But for biorecalcitrant substances, the Advanced Oxidation Processes (AOP) have remained the most efficient methods although expensive. Therefore, the coupling of biological-photocatalytic has emerged as the best compromise for removal of recalcitrant xenobiotics. The first step of the treatment strategy has consisted of evaluating the biotraitability of 19 chemicals: pesticides, pharmaceuticals and volatile organic compounds (VOCs) have been assessed according to three biodegradability methods (Zahn-Wellens, Manometric Respirometry, Closed-Bottle tests), whose official protocols had to be adapted to the compound specificities (volatility, hydrophobicity). Structure-Activity Relationship (SAR) estimation models have also been used to compare and validate the experimental results. For the compounds which have been assessed as biotraitable (VOCs), further biodegradation studies have been led in order to improve the treatment (batch with pulses of substrate): automated monitoring of the biodegradation process, increased degradation yields and biomass productivity have been successfully completed for Toluene, Ethylbenzene, Xylenes, Chlorobenzenze and Dichlorobenzene removal. Conversely, the compounds assessed as biorecalcitrant have been oriented towards the TiO2 and photo-Fenton photocatalytic treatments. Thus, the degradation of four p-halophenols by TiO2 photocatalysis has been investigated and has demonstrated the halogen effect on removal rates, aromatic intermediates and toxicity variations. Finally, the treatment of five bioreacalcitrant pesticides (Alachlor, Atrazine, Chlorfenvinphos, Diuron, Pentachlorophenol) has been studied in order to develop a coupled photocatalytic-biological system: first, enhanced biotreatability has been evaluated using the Zahn-Wellens procedure and then fixed-bed bioreactors have been operated and permitted to find out the best moment for coupling.

EPFL2006