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Pesticide became at the 20th century the generic term used to indicate all the natural Substance S or of synthesis able to control, attract, push back, destroy or to be opposed to the development living organisms (microbes, animals or plants) considered as undesirable for agriculture, the public health (for example the Cafard S in the dwellings), the public health (parasitic insects (lice, chips) or vectors of diseases such as the Paludisme and the pathogenic bacteria of water destroyed by chlorination), health veterinary surgeon, or surfaces not-agricultural (roads, airports, railways, electrical communications…).
The term “pesticide” covers a vaster field and general that expressions “Produit plant health” or “Produit phytopharmacological” because it includes all the intended products to fight against all the known as vermin, or undesirable (ex: the mushrooms which could attack a frame) and the veterinary medicinal products intended to protect the pets, game or of company (for example, the collar anti-chips for dog).
1. For purposes of this payment, the definitions contained in payment (EC) No 178/2002 like those given in article 2, items 1) and 4), of the directive 91/414/CEE apply. For purposes of this payment, one understands by: 4) " pesticides" , chemicals of the one of the two following subcategories: a) the pesticides used as produced phytopharmacological which concern the directive 91/414/CEE of the Council of July 15th, 1991 concerning the marketing of the phytopharmacological products (18); b) other pesticides, such as the products biocides like those concerning the directive 98/8/CE of the European Parliament and the Council of February 16th, 1998 concerning the marketing of the products biocides (19), and such as disinfecting, insecticidal and parasiticide concerned with the directives 2001/82/CE and 2001/83/CE HTTP: /eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32003R0304:FR:HTML
EtymologyThe etymology of the word pesticide was built on the model of the many words ending in the suffix “- cide” which originates in the Latin verb “ caedo , cadere ” and which means “ to kill ”. One associated to him the English root pest (animal, insect or harmful plant) or the French word plague (plague, pernicious thing which corrupt, disease), coming both from Latin Pestis who indicated the plague in general, and a dangerous disease in particular (however, Emile Littré in his dictionary of 1872-1877 quoted also Corssen which estimated that pestis came from perdtis (perdere, to lose, ruin).
HistoryThe “chemical” fight exists since millenia: the use of the Soufre goes up in ancient Greece (1000 years before J.C.) and the Arsenic is recommended by Pline, naturalist Roman, as an insecticide. Plants known for their toxic properties were used like pesticides (ex the Aconit, with the Middle Ages, against the rodents). Treaties on these plants wrote (Ex: treaty of the poisons of Maïmonide in 1135). The arsenical products or containing Plomb (Arsenate lead) were used at the 16th century in China and Europe.
Les insecticidal properties of the Tabac was known as of 1690. In India, the gardeners used the root S of Derris and Lonchocarpus (Roténone) like insecticide. Their use was spread in Europe towards 1900.
Inorganic chemistry developed at the 19th century, providing many mineral pesticides containing salts of Cuivre. The Fongicide S containing Copper sulfate are spread, in particular famous the Bouillie of Bordeaux (mixture of and copper sulfate Chaux) to fight against the fungic invasions of the vine and potato, not without after-effects of pollution on the grounds (copper not dégradable). Salts mercuriels are employed at the beginning of the 20th century for the treatment of the seeds.
The era of the pesticides of synthesis really begins in the years 1930, benefitting from the development of the organic chemistry of synthesis and research on the Chemical weapons during the First World War. In 1874, Zeidler synthesizes the DDT, whose Muller in 1939 establishes the insecticidal properties. DDT is marketed since 1943 and opens the way with the family of the Organochloré S. DDT dominated the market of insecticides until the beginning of the year 1970.
In 1944, the weedkiller 2,4-D, copied from a growth hormone of the plants and still strongly employed nowadays, is synthesized.
The Second world war generated, through the research engaged for the development poison gas, the family of the Organophosphoré S which, since 1945, saw a considerable development still setting today for some of these products, the such Malathion.
In 1950-55 develops in the United States the Herbicide S of the family of substituted ureas (Linuron, Diuron), followed shortly after by the Herbicide S of the quaternary group Ammonium and Triazines.
Fungicides of the benzimidazole type and pyrimides go back to 1966, followed by the Fongicide S imidazolic and triazolic said fungicidal IBS (inhibiting of the synthesis of the Stérol S) which currently represents the largest market of the Fongicide S.
In the years 1970-80 appears a new class of Insecticide S, the Pyréthrinoïde S which dominate for their part the market of insecticides.
Previously, the search for active matters was done randomly by subjecting many products to biological tests. When a product was retained for these biocides qualities, one sought to improve the effectiveness of it through the synthesis of analogues. This procedure made it possible to develop the techniques of syntheses which are of setting today.
From now on, the stress is laid on the comprehension of the modes of action and the search for new targets. Knowing the targets, one can then establish relations structure-activity to lead to obtaining active matters. This is possible thanks to the development of the basic research in the fields of biology and chemistry and with the new tools provided by the quantum chemistry, mathematics and the data processing which allow the modeling of these future molecules.
Currently, one witnesses a consolidation of the market on the level of the families most recently discovered with the search for new properties. In same time, new physiological targets of the animal or plant are explored with an aim of developing products with original modes of action, products resulting from biotechnology or transmitter substances.
ConsumptionThe tonnages used in the world have regularly increased for 60 years. They seem to decrease in certain countries in Europe, but it also should be held account owing to the fact that with amount or equal weight, the active matters of today, are much more effective than those of the previous decades; France remains, in 2006, the second world consumer of pesticides almost as much as the the United States but with an agricultural surface 10 times smaller. France and the Holland are the countries which consume the largest quantity of pesticides to the hectare.
The marketed molecules evolve/move, either by need for circumventing resistances of the insects, mushrooms or plants, or to replace products prohibited because of their toxicity, or because molecules considered to be more interesting come to replace others of them.
The most used pesticides (in term of quantity) are weeding them. The molecule activates the most sold like weeding and the most used in the world is the Glyphosate.
Design of a pesticide
- a pesticide is composed of a whole of molecules including/understanding:
- one (or several) active matter to which is due, in all or partly, the toxic effect.
- a thinner which is a solid matter or a liquid (solvent) incorporated in a preparation and intended has to lower the active matter concentration of it. They are generally plant oils in the case of the liquids, Argile or Talc in the case of the solids. In this last case the thinner is called charges.
- Of the additives which are substances deprived of biological activity, but likely to modify qualities of the pesticide and to facilitate its use of it.
There exists of share the world nearly 100 ' 000 commercial specialities authorized with the sale, composed starting from 900 different active matters. 15 to 20 new active matters are added there every year.
The properties of a pesticide rise essentially from the structure of its active matter. This one presents 3 parts (this cutting is artificial, no part not being able to be literally separate):
- an active structure, which ensures the capacity pesticide.
- of the chemical functions ensuring more or less great solubility in water.
- a support part for the two others conditioning solubility in oil.
This concept of solubility is important because it is the affinity of a pesticide for the water or the greasy substances which will condition its penetration in the target organization.
Other components: the formulation of a pesticideThe formulation of a pesticide aims has to present the active matter in a form allowing its application by adding substances intended to him to improve and facilitate its action. They are the additives. They include/understand the surface-active ones, adhesives, emulsifiers, stabilizing, of the antitranspirants, the dyes, the repulsive matters, the emetics (vomitory) and sometimes of the antidotes.
the formulation of a pesticide must answer 3 key objectives:
- to ensure an optimal effectiveness the active matter : the active matter must reach under the best conditions with its biochemical target, i.e. to reach that point as soon as possible with the minimum of loss. One thus limits his dispersion in the environment (cost ecological) and proportioning to the hectare necessary (economic costs). To this end one improves the contact with the target organization by the addition of wetting agents (the “dampening” are additives which improve spreading out of the pesticide on treated surface. They decrease the contact angle of the droplets with the vegetable support (or animal), with two consequences: a better adhesion and more a large surface of contact and action. For the systemic products, one seeks to improve the speed and balances of penetration as well as transport of the products in the plant. The formulation can also improve the biological effectiveness of the active molecule by effects of Synergie, additives which delay its degradation, thus prolonging its duration of action. Conversely, other additives can accelerate its elimination by the plants to be protected or in the ground.
- to limit the risks of intoxication for the manipulator : by seeking a minimal toxicity by contact and inhalation, by preventing accidental ingestions by the addition of dye, repulsive, antidote or vomitory (case of the Paraquat in Japan which are of color blue and equipped with a Vomitif). In the case of the liquids, the least toxic Solvant S are retained. The dilution of the active matter is all the more strong as the latter is highly toxic.
- to make profitable the active matter : the Solvant employed by the user is generally inexpensive and easily available. Various additives improve the conservation with storage and/or avoid the Corrosion material of spreading.
An international code of 2 capital letters, placed following trade name indicates the type of formulation. The principal types of formulation are the following:
solid presentations :
- the powders mouillables ( WP ): the active matter finely is crushed (solid) or is fixed (liquid) on a support adsorbing or porous (silica). Surface-active agents (dodecylbenzene, lignosulfonate of Ca, Al or Na) and loads of dilution (kaolin, Talc, Chalk, aluminum silicate and Magnesium or carbonates Ca) are added thus that agents anti-redepositions, anti-static or anti-foamer. Stabilizers (anti-oxygen and plug pH) are included to make them compatible with other preparations. These powders must be dispersed in water at the time of employment.
- pellets to be dispersed ( WG ): granulated obtained by the agglomeration with a little water of active matter, load and flexible and dispersing agents, followed by a drying. These powders must be dispersed in water at the time of employment.
- microgranulés ( MG ): identical to the WG but of a smaller size (0,1 to 0,6 mm).
liquid presentations :
- soluble concentrates ( SSL ): it is an active matter solution to be diluted in the water, added with surface-active agents.
- concentrated suspensions ( SC ): the solid, insoluble active matters in water are maintained in suspension concentrated in water, in the presence of Mouillant S, of dispersants, thickeners (Bentonite, Silice) or of agent anti-redeposition, antifreeze (ethylene glycol, Urée) of defoamers and sometimes of Bactéricide S (Méthanal or Formol). These preparations are diluted in water at the time of employment.
- the concentrated emulsible ones ( EC. ): the active matters are put in solution concentrated in a solvent organic and added with emulsifiers charged to stabilize the emulsions obtained at the time of employment by dilution in water.
- concentrated emulsions ( EW ): the active matter is dissolved in an organic solvent. The solution added with emulsifying agents is dispersed in an minor amount of water. This presentation is less toxic and less flammable than the emulsible concentrates.
Origin of the Environmental impacts
The dispersion of the pesticides in the groundsDuring a treatment, more than 90% of the quantities used of pesticides do not reach the ravageur concerned. The main part of the plant health products lead in the grounds where they undergo phenomena of dispersion. The risks for the environment are all the more great as these products toxic, are used on surfaces and with amounts/frequencies high and that they are persistent and mobile in the grounds.
The ground comprises biogenic salts and organic as well as living organisms. In the ground, the pesticides are subjected to the simultaneous action of the phenomena of transfers , of immobilization and degradation .
the phenomena of transfer
- the transfers to the surface of the ground relate to only one weak share of the products applied (generally less than 5%). They contribute to the water pollution of surface when they are involved, that is to say in a state dissolved or retained on trained ground particles themselves.
the phenomena of immobilization
- This phenomenon is due to the adsorption, which results from the attraction of the active matter molecules in gas phase or solution in the liquid phase of the ground by surfaces of the mineral components and organic of the ground. Many factors influence on the capacity of adsorption of a ground, related either to the characteristics of the molecule, or with those of ground (mineral and organic components, pH, quantity of water). In the same way, phenomena of desorption which corresponds to the release of the molecule in the ground (opposite phenomenon of adsorption).
the phenomena of degradation
- the ground is an ecosystem which has a capacity of very high detoxification. The processes of degradation of the active matters lead finally to obtaining mineral molecules such as H2O, CO2, NH3
The grounds behave like a filter active by ensuring the degradation of the plant health products, and selective, because they are able to retain some of these products.
In example, we will quote the case of the Oxychlorure of copper (Bouillie of Bordeaux) which accumulates in the grounds and which involved the sterilization of 50 ' 000 ha certain grounds of banana plantations to the Costa Rica.
Environmental impactsThey are complex and vary according to many factors, of which in particular:
- - the Toxicity and ecotoxicity of the active matter, surfactant or additives associated, their products breakdown (sometimes more toxic than the molecule-mother) and/or their Metabolite S;
- - a possible synergistic action with other pollutants or composed of the environment or touched organization;
- - the Durée of half-life of the active matter or the metabolites (if the active matter is biodegradable or dégradable);
- - duration and the amount (chronic exposure to low dose, exposure to amounts raised during a short time);
- - relative sensitivity of the bodies, the organization, the exposed ecosystem, at the time of the exposure and in the duration if the product or its effects is remanent;
- - the age of the body or the exposed organization (the embryo, the fetus, the cells in the course of multiplication are generally more sensitive to the poisons).
- - a possible synergistic action with other pollutants or composed of the environment or touched organization;
The pesticides can be responsible for Pollution S diffuse and chronic and/or acute and accidental, during their manufacture, transport, use or during elimination of products at the end of the lifetime, degraded, unutilised or prohibited.
The pesticides, their products breakdown and their Métabolite S can contaminate all the compartments of the Environment;
- - Air (external, interior), like in particular showed it a study made over 3 years by the Institut Pasteur of Lille, in the north of France starting from 586 taking away made out of 3 different sites (3 gradiants of population Urbanisation and intensity of the Agriculture).
- - Water X (salted, brackish, soft, of tablecloth, surface. Water meteoritic (rains, snow, spindly, fog, dew are also concerned),
- - ground. Certain pesticides little dégradables are strongly adsorbed on the grounds which they can pollute durably (Chlordécone, Paraquat for example)
- - Water X (salted, brackish, soft, of tablecloth, surface. Water meteoritic (rains, snow, spindly, fog, dew are also concerned),
… Certains pesticides remanent can - a long time after their use, to persist and pass from one compartment to the other; that is to say passively (Desorption, evaporation, erosion.) that is to say actively via biological processes (metabolisation, Bioturbation, Bioconcentration, etc). It is the case for example DDT which one still finds of the decades after his prohibition in certain areas, distant from any direct source of pollution.
One finds them in the form of “residues” (molecule mother, products and by-products of degradation or metabolites) in our food and drinks. Laws or European Directive S force thresholds not to be exceeded, of which in drinking water.
Impacts on qualityIt is a discussed question.
Les manufacturers estimates that the pesticides improve quality of the products, in particular by reducing the risk of development of certain bacteria or mushrooms producing of the Toxine S.
Mais the detractors of the pesticides or of their systematic use assert that:
- many these pathogenic develops can with little of resistances to the pesticides, as the microbes deal it with antibiotics too used.
- the residues of pesticides accumulated on and in the livestock plants or products could pose problems for health
- the residues of pesticides could pose problem for the animals which consume waste of agribusiness industry
- the grounds which are degraded under the action of the pesticides end up producing fruit and vegetables of less quality.
According to a study of the University of California, published in the review Chemistry & Industry (March 26th, 2007), of the researchers compared the kiwis of the same orchard produced with the same moment, the ones in agriculture bio , and the others with pesticides. With harvest, kiwis “ bio ” significantly contained more vitamin C, more minerals and more polyphenols (organic compounds supposed “good for health”, because reducing the formation of free radicals). The researchers estimate that untreated kiwis develop their mechanisms of defense better; being stressed, they manufacture for example more antioxydants.
Risks and dangers to the human health
Various types of intoxications
Acute intoxicationsThe time which separates the exposure to the product and the appearance of the disorders is relatively short, of a few hours to a few days, generally making it possible to connect the effects to the cause.
The organochlorinated derivatives induce first of all digestive disorders (vomiting, diarrhea) followed by central nervous system disorders (headaches, giddiness) accompanied by a great tiredness. This succeed of the convulsions and sometimes a loss of conscience. If the subject is covered in time, the evolution towards a cure without after-effects generally occurs. The acute intoxication with this type of product is relatively rare, with less of voluntary ingestion (suicide) or accidental (absorption by mistake, drift of cloud, jet of pulverizer…).
The organophosphorés derived as well as the carbamates , by inhibiting the Cholinestérase, induce an accumulation of Acétylcholine in the organization leading to a hyperactivity of the nervous system and with a cholinergic crisis. The clinical signs are digestive disorders with salivary hypersecretion, nausea, vomiting, abdominal cramps, diarrhea profuse. There is moreover of the respiratory disorders with bronchial hypersecretion, cough and breathlessness. The cardiac disorders are a tachycardia with hypertension then hypotension. The disorders neuromusculaires result in frequent and fast contractions of all the muscles, involuntary movements, cramps then a general muscular paralysis. Death occurs quickly by asphyxiation or cardiac arrest. A specific antidote exists for this category of product: sulfate of atropine which neutralizes the toxic effects quickly.
In the adult, the products rodenticides containing anticoagulants generally do not involve - with less of massive absorption with suicidal goal of disorders of coagulation, nor of hemorrhage. On the other hand, in the child, of the serious hemorrhages can occur. It act by lowering the rate of prothrombine in blood, necessary to the formation of the blood clot, thus involving internal bleedings. The symptoms appear after a few days for an amount raised, after a few weeks for repeated catches: blood in the urines, nosebleed, gingival hemorrhage, blood in the saddles, weakens, weakness. Death can occur in the 5 to 7 days which follow.
According to the agricultural Social insurance system (MSA) and laboratory GRECAN, first studies MSA concluded in France that approximately 100 to 200 acute intoxications (cutaneous irritations, digestive disorders, headaches) per annum are charged to the pesticides.
dermatological Attacks : rednesses, itchings with possibility of ulceration or cracking, urticaria are very frequently observed, concerning rather the parts discovered of the body (arm, face). Many products cause cutaneous problems, of which roténones responsible for severe lesions on the level of the genital areas.
neurological Attacks : the Organochloré S reveal a muscular fatigability, a fall of the tactile sensitivity. The Organophosphoré S involve in the long run cephalgias, anxiety, irritability, depression and insomnia, sometimes allied with hallucinatory disorders. Some cause a paralysis, like the derivatives mercuriels or arsenical.
Turbid of the system hematopoietic : the Organochloré S can cause a reduction in the rate of red globules and globules white, with risk of leukemia.
Reached cardiovascular system : the Organochloré S develop phenomena of palpitation and disturbance of the cardiac rhythm.
Reached respiratory system : these attacks are often in relation to the phenomena of irritation generated by good numbers of pesticides, thus supporting superinfections and being at the origin of bronchitides, rhinitides and pharyngitides. Reached sexual functions : a nématicide (DBCP) caused at the employees of the factory where it is synthesized a big number of case of Infertilité. Other substances seem implied in the increasing délétion of the Spermatogenèse.
fetal Risks : pesticides cross the placental barrier and have a teratogenic action on the embryo. It is the case of DDT, of the Malathion, phthalimides (fungicide close to the Thalidomide). It can occur of the premature births or the abortions. It is advised with the expectant mother to avoid handling pesticides between the 23e and the 40e day of the pregnancy.
neurodégénratives Diseases : A study published in 2006 concluded with an increase from the risks from Parkinson's disease following the exposure to certain pesticides, in particular… to see the summary.
Cancers: the GRECAN highlighted a lower number of cancers in the farmers than in the general population, but with a higher occurrence of certain cancers (prostate, testicles, brain (Gliome S)…). There exists in the world about thirty studies which show a whole a rise in the risk of cerebral tumors.
the study of Isabelle Baldi : A study concluded semi-2007 which the risk of cerebral tumor more than is doubled in the very exposed farmers with the pesticides (all types of confused tumors, the risk of Gliome S being even triplet). The inhabitants using of the pesticides on their plants of interior also have a risk more than doubled to develop a cerebral tumor the study does not make it possible to say if a product or a family of pesticide would be more responsible than others, but the author notes that fungicides are 80% of the pesticides used by the vine growers.
Prevention and control
Since 2006, the French Agence of public health of the food S (Afssa) is charged to test the pesticides put on the market, before their homologation. Thus, Afssa prohibited in 2001 the treatment of the vines to arsenic after the discovery of suspect pathologies.
Pesticides, revelations over a French scandal (Beech, 2007)
- pesticides, an health hazard proven but still badly taken into account , Le Monde, June 11th, 2007
Fears of hormonal disturbancesCertain pesticides behave like “ hormonal lures ”. At 100% of the 308 Spanish expectant mothers, having then given rise to children judged in good health between 2000 and 2002, one found at least a type of pesticide in the Placenta (which contained on average 8 of them, and up to 15, among 17 sought pesticides, organochlorinated, because being also disturbing endocriniens). The most frequent pesticides were in this study the 1,1-dichloro-2,2 (a) (p-chlorophényl) - ethylene (DDE) with 92,7%, the Lindane to 74,8% and the endosulfan-diol with 62,1% (lindane is prohibited, but very persistent).
See also: Trade-guild (botanical)
Many plants naturally produce substances to be protected: thus the Tabac produces the Insecticide Nicotine, and the Chrysanthème of the Pyréthrine. This logic was thorough further by the introduction of genetically modified plants which also produce they, generally throughout their cycle of growth, their own active matters (thus LT, a insecticidal Protéine produced originally by a Bactérie , which is produced in the plant genetically modified on the level of the root S, stems, sheets and Pollen, but not in seed) or of the substances Fongicide S or Bactéricide S (is necessary it to classify these organizations artificially created among the pesticides?).
Resistances to the pesticides
DefinitionResistance to the pesticides is the resultant of a selection of organizations tolerating of the amounts which kill the majority of the normal organizations. The resistant individuals multiply in the absence of intraspecific competition and they become in very few generations the majority individuals of the population.
Resistance is defined by WHO as “the appearance in a population of individuals having faculty to tolerate toxic substance amounts which would exert a lethal effect on the majority of the individuals composing a normal population of the same species”.
It results from the selection, by a pesticide, mutants which have enzymatic or physiological equipment enabling them to survive lethal amounts of this pesticide.
Let us note that a pesticide is satisfied to select resistance, but does not create it.
Resistance to insecticidesSince the first case recorded (resistance of the louse of San Jose to polysulfides in the orchards of Illinois in 1905) the cases of resistance increased in an exponential way: 5 cases in 1928,137 in 1960,474 in 1980. In 1986,590 animal species and vegetable had a resistance: 447 species of insects or acarina, a hundred the pathogenic ones of the plants, 41 species of bad grasses as well as nematodes and rodents.
Many cases of resistances to insecticides are certainly anecdotic, relating to only one particular place. On the other hand, others spread with the whole world, as for the domestic fly resisting organochlorinated or the Tribolium (worm of the flour) resistant to the Lindane and the Malathion. The mosquito Culex pipiens developed raised resistances to organophosphorés.
All the families of insecticides can induce resistances in the insects. The pyrethrinoid ones and analogues of the youthful hormones escape the rule by no means, with 6 cases of resistance to pyrethrinoid in 1976, exploding with 54 cases in 1984.
On the other hand, at the taxonomic level, the various orders of insects express varied sensitivities. The Diptère S present the greatest number of cases of resistance, followed by the Hémiptères (plant louses and bugs). The Coleopter S, Lépidoptères and Acariens represent each one 15% of the cases of resistance. On the other hand, the Hyménoptères seem refractory with the development of resistance, undoubtedly for genetic reasons.
In 1984, one knew 17 species of insects and acarina resistant to the 5 independent groups of pesticides: the Colorado beetle of potato, the plant louse of fishing, the tinea of the crucifères, the worm of the capsule, the Spodoptera cut worms and the species of Anophèle S.
Let us note that resistance is sometimes required: it is the case for the predatory acarina Phytoseiulus persimilis used against Tétranyques of the greenhouses.
The cultures most concerned with the phenomena of resistance are cotton and fruit-bearing arboriculture. One can quote the case of the white fly Bemisia tabaci (Aleurode) in the cotton cultures of the plain of Gézira to the Sudan with the beginning of the year 1980 or that of cicadelles of rice in Far East and in the South Is Asian. In particular, in Indonesia, the chemical fight against Nilaparvata lugens proved to be impossible in the middle of the years 1980, obliging the country to turn to a concept of integrated protection of the rice plantations in 1986.
factors of resistanceThe factors supporting the appearance of a resistance are classified in 3 groups:
- genetic factors: frequency, number and predominance of genes of resistance, expression and interaction of these genes, former selection by other active matters, level of integration of gene resisting and the adaptive value.
- biological factors: generation time, descent, monogamy or polygamy, Parthenogenesis and certain conportementaux factors (mobility, migration, polyphagia, zone refuge).
- operational factors: chemical structure of the product and his relationship with the former products, persistence of the residues, proportioning, threshold of selection, selected stage, mode of application, selectivity of the product, alternative selection.
The first two types of factors are inherent in the species and cannot be - a priori - modified by the man, who will be able to intervene only on the level of the third group.
It is possible to establish a hierarchisation of the dominating factors to the appearance of the phenomena of resistance. Most important are:
- the number of annual generation : the risk of appearance of a resistance is all the more great as the duration of the development cycle is short and the number of annual generations high. The appearance of resistance is thus related to the number of generations having undergoes a pressure of continuous selection.
- the mobility of the populations : the surge of migrants strongly decreases the frequency of resistance among the survivors of a treatment by diluting genes of resistance in the population.
- the predominance of genes of resistance : resistance will appear more quickly, in interaction with the amount applied which will influence the expression of predominance: for low dose, the sensitive hétérozygotes are destroyed but the resistant hétérozygotes will survive, involving a functional predominance of resistant gene.
Strategy of limitation of resistanceLet us recall that the increase in amount applied does nothing but increase the pressure of selection. In the same way, the multiplication of the treatments only results in eliminating the sensitive migrants likely to dilute genes of resistance. It is thus necessary to exploit the operational factors while seeking to limit to the maximum the pressure of selection. To this end, it is necessary:
Choisir an insecticide sufficiently different from those used before
- Respecter the amount of application
- the application must be localized in time and space
- Utiliser synergistic products
- Diversifier the methods of fight.
Many plants were modified genetically to be tolerant with one weeding total (the Glyphosate). They thus contribute to generalize the use of this weeding, with the risk to extend resistances which start to appear at certain plants.
ResiduesA programme of follow-up of the residues of pesticides in vegetable foods of the European commission is undertaken annually, based on the results of analyzes of more than: 60000 samples taken in all the European Union. A representative of the European commission had the results of the analyzes of the samples taken in 2004 at a meeting of the “Work group on the residues of pesticides” which proceeded in Corfou (Greece) from May 21st to 25th 2006.
In France, for the year 2004 controls of the DGCCRF (Direction of the Competition of the Ministry for Finances) indicate:
- less than 4% of the fruit and vegetables controlled in France presents content of pesticides higher than the authorized Maximum Limit
- the cereals and the cereal products present 2,4% of nonconformity on 330 samples.
No nonconformity was detected on the juices of oranges and the products containing fruits or of vegetables intended for the infantile food.
However, these results are to be inserted in a critical reflection on the economic channels of the manufacture and marketing of the pesticides. Among others, authors of the books quiet Spring (1963) and Pesticides. The revelations on a French scandal (2007) denounced the partiality of the commissions of evaluations of the risks and damage.
LabellingEach product is matched with a homologation for one or more specific uses which must be specified on the label. The class of danger must also be reproduced on the label, represented by an international logo.
Labelling here in question is that of the container containing the pesticide. As regards the fruit and vegetables bound for the human consumption, to date, no mention of the pesticides used during the phases of growth and maturation is placed at the disposal for the ultimate consumer.
MonitoringThe commercial data (sales, orders) precise and géo-rérérencées would be useful for the epidemiologists and ecoepidemiologists, but they are regarded as confidential by the producers. The pesticides volitilized in the air, or transported by water and adsorbed on the particles of the ground are difficult to follow. One measures only part of the molecules used, and even less the molecules of degradation. Also, to have data and to respect the convention of Aarhus on the access to information environmental, certain countries build stuctures of long-term monitoring, of which France with a French Observatoire of the Observatoire pesticides of the residues of pesticides (ORP) created by the French Agence of public health of the environment and the work (AFSSET) which since 2007 started to put on line a chart of interactive France giving access to the available data on the presence of residues of pesticides in the air, water, grounds and certain foodstuffs. The agency encourages the owners of data on the pesticides with volontairmenet to contribute to voluntarily update this tool.
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