Pesticides

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pesticides Californie
Since the 1940s, global pesticide consumption has been steadily on the rise, increasing from 0.49k/ha in 1961 to 2kg/ha in 2004. In the United States and France, pesticides are used on 20% and 35% of the total surface area, respectively.

Europe represents nearly one-third of the world pesticide market of $30 billion/year, while North America and Asia each share roughly 25% of the world market. The United States is the leading consumer of pesticides, followed by India and France, the main European consumer before Germany. Per hectare, Japan uses 12 kg, Europe 3 kg and the United States 2.5 kg, far surpassing India (0.5 kg/ha), which is also one of the world’s primary producers. These products are responsible for poisoning 3 million people annually and according to the WHO, may be the cause of 20,000 to 200,000 accidental deaths each year, mainly in developing countries where approximately 30% of pesticides on the market do not comply with international standards of quality.

Pesticides, or phytosanitary products, are substances intended for preventing, controlling or eliminating pests (weeds, insects/rodents, fungi or micro organisms) that may compete with or harm plants. There are 520 approved active ingredients contained in nearly 3000 products on the market. They are used for agriculture, road and rail infrastructure maintenance, wood treatment and various other private purposes (gardening, treating premises, etc.). There are three main categories of pesticides GLOSSARY: herbicides, fungicides and insecticides. In Europe and North America, herbicides constitute 70-80% of products used whereas in the tropics, insecticides account for 50%. China’s development of genetically modified organisms (GMO) has made it the major player in the rise in herbicide consumption. According to the FAO, herbicides have significantly increased agricultural yield throughout the 20th century, enabling more consistent production. However, it is difficult to isolate the beneficial effects attributable to their use from those simultaneously produced by fertilizers and irrigation.

Environmental contamination

Environmental contamination occurs through air dispersion of pesticides during treatment (especially by spraying), windborne erosion of treated soil, groundwater seepage GLOSSARY and run-offs. Once in the atmosphere, pesticides are usually decomposed by visible radiation, but they may travel long distances and fall back down during rainfall. INRA readings have shown that rainwater and fog can contain from 0.1 µg/l to 14 µg/l of pesticides, respectively. They contaminate soil, surface and ground water, as well as plants and animals. Their life span can last several years and largely depends on their solubility (influence on decomposition by micro organisms) and the structure and permeability of soil.

Pesticides can also be detrimental to biodiversity by causing the extinction or decline of certain species or promoting the replacement of pollution-sensitive species with pollution-tolerant species, as the eradication of one species can disrupt the entire food chain.

The environment can also be contaminated when washing equipment or disposing of pesticides or their recipients unsafely and illegally.

In France in 2004, pesticides were detected in 96% of waterway gauging stations and 61% of ground water gauging stations. Contamination levels were also often high with 49% of surface water gauging stations revealing average to poor quality. The ground water points showed that 27% of stations would require specific treatment to eliminate pesticides if they were used to produce drinking water.

Abundance of obsolete stocks

According to the United Nations Food and Agriculture Organization, the accumulation of unused or obsolete stocks of pesticides represents a serious and growing threat for populations and the environment in Eastern Europe, Africa, Asia, Middle East and Latin America. Ukraine is reported to possess approximately 19,500 tonnes of these outdated chemicals, Macedonia 10,000 tonnes, Poland 15,000 tonnes and Moldavia 6,600 tonnes. In Asia, there may be 6,000 expired stocks, without counting China. Middle Eastern and Latin American countries have declared approximately 10,000 tonnes.

Better understanding of human effects

In 2004, 47% of fruit, vegetables and cereals consumed in Europe contained pesticide residues according to the annual DG SANCO report. The French Institute for the Environment reported that 5.5% of fruit and 7% of vegetables exceeded the maximum limit of pesticide residue in 2003. An American study revealed that the air inside homes may contain anywhere from ten to eighteen pesticides.

In humans, pesticides can cause cancers, endocrinal and nervous system disorders, birth defects, etc. According to a study conducted by the European Federation of Farm Worker Unions, workers and operators directly exposed to pesticides while applying, preparing or handling containers, most commonly reported acute headaches, vomiting, stomach pains, and diarrhea, even during low levels of exposure. In France, one user in five experienced symptoms at least once in the year.

Populations who are indirectly exposed to pesticides (residual quantities of pesticides in farm products or water) may present with symptoms, especially children who are particularly sensitive to the supposed “cocktail effects” of pesticides, elderly persons, persons suffering from chronic illnesses, etc. Although the issue of human risks is still under debate, it has been given priority in all the Health and Environment plans of action.

Currently, organic agriculture is the only production method whereby pesticide residue is nearly inexistent. Reasoned agriculture or integrated production (Integrated Pest Management) can reduce the quantities of pesticides used without banning them completely. This method is applied in three quarters of farmed land in Switzerland.

The lower pesticide consumption rates observed in industrialized countries can be misleading. In fact, the development of new molecules that are more effective and more specific (higher toxic equivalent for equal quantities) enable smaller doses to be used. Therefore, the effective dose of second generation DDT has decreased from 1kg on average to 12g/ha.

Different strategies might be used to reduce pesticide’s use

– Limitation of pesticide dispersion into the environment and losses at application

– Interception of pollution flows

– Predator-resistant GMOs (MON 863 containing an artificial Bt toxin)

– Genetic improvement of crops to resist pests

– Biological management by introducing the pests’ natural enemies using biological mechanisms such as sexual confusion, activation of natural defenses

– Mechanical or physical management (weed control, physical barriers) or heat mechanism (soil disinfection)

– Association crops to reinforce defenses and reduce risks of pest attacks

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