Автор: Сидоренко Малина
Рубрика: 3. Медико-биологические дисциплины
Статья просмотрена: 42 раза
Сидоренко М. Pesticides [Текст] // Медицина и здравоохранение: материалы Междунар. науч. конф. (г. Чита, ноябрь 2012 г.). — Чита: Издательство Молодой ученый, 2012. С. 1-10.
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest. Pesticides are a special kind of products for crop protection.  Crop protection products in general protect plants from damaging influences such as weeds, diseases or insects.  A pesticide is generally a chemical or biological agent (such as a virus, bacterium, antimicrobial or disinfectant) that through its effect 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, spread disease or are vectors for disease.  Pesticide formulations contain both "active" and "inert" ingredients. Active ingredients are what kill the pest, and inert ingredients help the active ingredients to work more effectively.  Although there are human benefits to the use of pesticides, some also have drawbacks, such as potential toxicity to humans and other animals. According to the Stockholm Convention on Persistent Organic Pollutants, 9 of the 12 most dangerous and persistent organic chemicals are pesticides. Pesticides are categorized into four main substituent chemicals: herbicides; fungicides; insecticides and bactericides. Pesticides can be classified by target organism, chemical structure, and physical state. Pesticides can also be classed as inorganic, synthetic, or biologicals (biopesticides). Biopesticides include microbial pesticides and biochemical pesticides. Prominent insecticide families include organochlorines, organophosphates, and carbamates. Organochlorine hydrocarbons (e.g. DDT) operate by disrupting the sodium/potassium balance of the nerve fiber, forcing the nerve to transmit continuously. Their toxicities vary greatly, but they have been phased out because of their persistence and potential to bioaccumulate.:239-240 Organophosphate and carbamates largely replaced organochlorines. Both operate through inhibiting the enzyme acetylcholinesterase, allowing acetylcholine to transfer nerve impulses indefinitely and causing a variety of symptoms such as weakness or paralysis. Organophosphates are quite toxic to vertebrates, and have in some cases been replaced by less toxic carbamates.:136-137 Prominent families of herbicides include pheoxy and benzoic acid herbicides (e.g. 2,4-D), triazines (e.g. atrazine), ureas (e.g. diuron), and Chloroacetanilides(e.g. alachlor). Many commonly used pesticides are not included in these families, including glyphosate.
Pesticides can be classified based upon their biological mechanism function or application method. A systemic pesticide moves inside a plant following absorption by the plant. Systemic insecticides, which poison pollen and nectar in the flowers, may kill bees and other needed pollinators. In 2009, the development of a new class of fungicides called paldoxins was announced.  These work by taking advantage of natural defense chemicals released by plants called phytoalexins, which fungi then detoxify using enzymes. The paldoxins inhibit the fungi's detoxification enzymes. They are believed to be safer and greener.
Pesticides work by interfering with an essential biological mechanism in the pests, but because all living organisms share many biological mechanisms, pesticides are never specific to just one species. While pesticides may kill pests, they may also kill or harm other organisms that are beneficial or at least not undesirable. They may also harm people who are exposed to pesticides through occupational or home use, through eating foods or liquids containing pesticide residue, or through inhaling or contacting pesticide-contaminated air. The ideal pesticide would be highly specific to only the target organism, be quick acting, and would degrade rapidly to harmless, inert materials in the environment. Pesticides - History Pesticides have been in use for centuries. In 470 B.C., the Greek philosopher Democrates used olive extracts on plants to prevent blight. Biological control was found effective by the ancient Chinese who used ants to protect their trees from insect pests. One of the first pesticides was sulfur, used by the Chinese in around 1000 BC to control bacteria and mold (fungus). Sulfur is still widely used today. For example, it is used in the wine industry to control unwanted bacterial growth in empty wine barrels and is commonly added to wine to kill unwanted yeast. The Chinese also pioneered the use of arsenic-containing compounds to control insects.  Arsenic has a long history of use both as an insecticide and herbicide, and also as a medicine.  Plants have provided several other important nonsynthetic pesticides. In the late 1600s nicotine, an extract from tobacco leaves, was recognized as a potent insecticide and is now in limited use as a pesticide. Another group of nonsynthetic insecticides is pyrethrums, which are harvested and refined from chrysanthemums. The Strychnine tree, Nux vomica, contains strychnine used to kill rodents. Plant extracts are useful for controlling pests, but they are often difficult to purify and produce in large quantities. Synthetic chemistry advanced rapidly in the 1930s and by the early 40s, a range of new pesticides had been developed, including organochlorine insecticides like DDT.  Herbicides were developed after WWII in order to increase food production and create possible warfare agents. These herbicides have been extensively utilized in agriculture and to clear roadsides and rights of way. 2,4,5-T was used extensively during the Vietnam War to defoliate jungle plants.  Dioxins, like other chlorinated compounds including DDT, bioaccumulate in body fat and persist in the environment for many years (the soil half-life is 10 to 12 years).  Dioxins are classified as carcinogens and are also known to affect the reproductive and immune systems. Usage
Pesticides are used to control organisms that are considered to be harmful. For example, they are used to kill mosquitoes that can transmit potentially deadly diseases like West Nile virus, yellow fever, and malaria. They can also kill bees, wasps or ants that can cause allergic reactions. Insecticides can protect animals from illnesses that can be caused by parasites such as fleas.  Herbicides can be used to clear roadside weeds, trees and brush.  Toilet bowl cleaners and disinfectants often contain pesticides. The pesticides in wool and our wood makes our clothes and furniture last longer. Raw commodities and packaged grocery products—the foods we eat—are protected from insect contamination by the controlled use of insecticides in processing, manufacturing, and packaging facilities.  Herbicides are commonly applied in ponds and lakes to control algae and plants such as water grasses that can interfere with activities like swimming and fishing and cause the water to look or smell unpleasant. The role of pesticides in protecting public health is broad and varied. Water utility companies apply the pesticide chlorine to public drinking water to kill harmful bacteria. Pesticides known as disinfectants eliminate dangerous organisms that cause Legionnaire’s disease, and hospitals rely on disinfectants to prevent the spread of bacteria such as Staphylococcus. Rodenticides are used in public housing units to control rodents that carry diseases such as the deadly hantavirus.  Avicides are used to control birds near silos and grain storage buildings, reducing the likelihood of grain contamination and exposure of workers to the lung disease histoplasmosis. Insecticides control insects that vector disease, inflict painful bites, and cause stress on livestock.  They are applied to the animals and/or their stalls, pens, corrals, barns, and etc.  Herbicides are also used on athletic fields, parks and playgrounds.  Pesticides are routinely combined with nonchemical pest management strategies. Nonchemical pest solutions are effective in certain situations: planting resistant varieties for apple scab control, mowing or tilling for weed control in problem areas, using pheromones (sex attractants) to lure and capture insects, etc.
Presently, we are using more pesticides than ever. The EPA (Environmental Protection Agency) reported that 4.9 billion pounds of pesticide products were used in the United States in 2001, which is equivalent to 4.5 pounds per person. Although most modern pesticides are much safer than their predecessors, a few of our commonly used pesticides are considered toxic.
Environmental Protection Agency (EPA)has made a report, Pesticides Industry Sales and Usage: 2006 and 2007 Market Estimates. It illustrates graphically historical trends and levels of use over the last 20 years. Highlights include:
In the United States, pesticide sales were approximately $12.5 billion at the user level, which accounted for 32% of the nearly $40 billion world market in 2007.Pesticide use in the United States was 1.1 billion pounds in 2007, or 22% of the world estimate of 5.2 billion pounds of pesticide use.
Total pounds of U.S. pesticide use decreased by approximately 8% from 1.2 to 1.1 billion pounds from 2000 to 2007.
Use of conventional pesticides decreased about 3% from 2002 to 2007 and 11% from 1997 to 2007.
Approximately 857 million pounds of conventional pesticide active ingredient were applied in 2007.
Organophosphate insecticide use decreased about 44% from 2002 to 2007, 63% from 2000 to 2007, and 55% from 1997 to 2007.
About 33 million pounds of organophosphate insecticides were applied in 2007.
Eighty percent of all U.S. pesticide use was in agriculture.
Herbicides remained the most widely used type of pesticide in the agricultural market sector.
Herbicides were also the most widely used type of pesticide in the home and garden and industrial, commercial, and governmental market sectors, and the herbicides 2,4-D and glyphosate were the most widely used active ingredients. 
In lab tests where high doses of pesticides were given, researchers have observed some significant health effects. Genetic damage, reproductive problems, and possible links to cancer are just some of the risks associated with pesticides. Each use of a pesticide carries some associated risk. Proper pesticide use decreases these associated risks to a level deemed acceptable by pesticide regulatory agencies such as the United States Environmental Protection Agency (EPA) and the Pest Management Regulatory Agency (PMRA) of Canada.  According some authors pesticides can save farmers' money by preventing crop losses to insects and other pests; in the U.S., farmers get an estimated fourfold return on money they spend on pesticides.  One study found that not using pesticides reduced crop yields by about 10%. Another study, conducted in 1999, found that a ban on pesticides in the United States may result in a rise of food prices, loss of jobs, and an increase in world hunger.
DDT, sprayed on the walls of houses, is an organochloride that has been used to fight malaria since the 1950s. Recent policy statements by the World Health Organization have given stronger support to this approach. However an October 2007 study has linked breast cancer from exposure to DDT prior to puberty. Poisoning may also occur due to use of DDT and other chlorinated hydrocarbons by entering the human food chain when animal tissues are affected. Symptoms include nervous excitement, tremors, convulsions or death. Scientists estimate that DDT and other chemicals in the organophosphate class of pesticides have saved 7 million human lives since 1945 by preventing the transmission of diseases such as malaria, bubonic plague, sleeping sickness, and typhus. However, DDT use is not always effective, as resistance to DDT was identified in Africa as early as 1955, and by 1972 nineteen species of mosquito worldwide were resistant to DDT. A study for the World Health Organization in 2000 from Vietnam established that non-DDT malaria controls were significantly more effective than DDT use. The ecological effect of DDT on organisms is an example of bioaccumulation.
EU and Bulgarian legislation
EU legislation on undesirable substances in feed begins in 1974 - Directive 1999/29/EC of undesirable substances and products in animal nutrition. There is set limits for many substances as arsenic, mycotoxins, pesticides, botanical purity. 
EU rules on plant protection products establish a “dual” system:
The Commission approves the active substances contained in the products;
EU countries authorise the products on their territory and ensure compliance with EU rules.
As laid down in Directive 91/414/EEC, in 1993 the European Commission launched the work program on the Communitywide review for all active substances used in plant protection products within the European Union.  In this review process, each substance had to be evaluated as to whether it could be used safely with respect to human health (consumers, farmers, local residents and passers-by) and the environment, in particular groundwater and non-target organisms, such as birds, mammals, earthworms, bees. 
There are some Regulations and Directives concerning pesticides:
Commission Directive 2001/35/EC of 11 May 2001 amending the Annexes to Council Directive 90/642/EEC on the fixing of maximum levels for pesticide residues in and on certain products of plant origin, including fruit and vegetables
DIRECTIVE 2002/32/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 7 May 2002 on undesirable substances in animal feed
Directive 2009/128/EC of the European Parliament and of the Council of 21 October 2009 establishing a framework for Community action to achieve the sustainable use of pesticides
REGULATION (EC) NO 396/2005 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 23 February 2005 on maximum residue levels of pesticides in or on food and feed of plant and animal origin and amending Council Directive 91/414/EEC
REGULATION (EC) No 1107/2009 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 21 October 2009 concerning the placing of plant protection products on the market and repealing Council Directives 79/117/EEC and 91/414/EEC
COMMISSION REGULATION (EU) No 277/2012 of 28 March 2012
amending Annexes I and II to Directive 2002/32/EC of the European Parliament and of the Council as regards maximum levels and action thresholds for dioxins and polychlorinated biphenyls
COMMISSION REGULATION (EU) No 744/2012 of 16 August 2012
amending Annexes I and II to Directive 2002/32/EC of the European Parliament and of the Council as regards maximum levels for arsenic, fluorine, lead, mercury, endosulfan, dioxins, Ambrosia spp., diclazuril and lasalocid A sodium and action thresholds for dioxins
There are also some other Regulations concerning common requirements of control, hygiene and traceability:
REGULATION (EC) No 178/2002 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 28 January2002 laying down the general principles and requirements of food law, establishing the European Food Safety Authority and laying down procedures in matters of food safety
REGULATION (EC) No 882/2004 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 29 April 2004 on official controls performed to ensure the verification of compliance with feed and food law, animal health and animal welfare rules
REGULATION (EC) No 183/2005 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 12 January 2005 laying down requirements for feed hygiene
According to REGULATION (EC) No 882/2004 member states have a duty to control:
Eliminate or reduce the risks to acceptable levels.
Ensuring fair trade practices and protect interests of the consumers
Monitoring should be carried out regularly and based on the assessment of risk and frequently
Controls to identify risks, past records line, the reliability of self-control, information discrepancies.
At all stages of production, processing, distribution and use.
…and some uncommon regulations:
REGULATION (EC) No 767/2009 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 13 July 2009 on the placing on the market and use of feed, amending European Parliament and Council Regulation (EC) No 1831/2003 and repealing Council Directive 79/373/EEC, Commission Directive 80/511/EEC, Council Directives 82/471/EEC, 83/228/EEC, 93/74/EEC, 93/113/EC and 96/25/EC and Commission Decision 2004/217/EC
COUNCIL DIRECTIVE 1999/29/EC of 22 April 1999 on the undesirable substances and products in animal nutrition (Amended with aforementioned DIRECTIVE 2002/32/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 7 May 2002 on undesirable substances in animal feed)
Bulgarian Agency for Food Safety is the competent state authority to carry out official controls in Bulgaria under EU legislation regulating the activities (required to art. 3, para. 1.)  Bulgarian Agency for Food Safety (BFSA) was established to Minister of Agriculture and Food with a Law for Bulgarian Agency for Food Safety from 25.01.2011.
Despite the fact that pesticides have aided in the control of malaria, schistosomiasis, and filariasis in tropical countries, there are still 150 million cases of malaria and about 250 million cases of schistosomiasis and filariasis each year in the world. There is no way of knowing and no way to calculate how many lives will be saved or improved by the use of pesticides to control diseases and increase our food production. Likewise there is no way to calculate how many lives will be lost from pesticide use either. Some dangerous pesticides that are banned or restricted in North America and Europe have been unloaded on Third World countries. 
May be it’s time to think about natural defence as the ancient Chinese did using ants against insect pests. The first step is done if we read carefully some of the Regulations and Directives of the EU legislation. Directive 2009/128/EC shows us some ancient and simple way to do that - crop rotation, use of adequate cultivation techniques (e.g. stale seedbed technique, sowing dates and densities, under-sowing, conservation tillage, pruning and direct sowing), use of balanced fertilisation, liming and irrigation/drainage practices, preventing the spreading of harmful organisms by hygiene measures (e.g. by regular cleansing of machinery and
equipment) (Annex III). As characters in a cartoon says “Power is in your hands” References:
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