Agricultural chemicals

The agricultural pesticides (pesticides, agrochemicals)are chemical substances used in agriculture for the control of pests and plant diseases, to destroy weeds.
All chemicals used in agricultural practice, depending on the destination are divided into the following groups:
insecticide - means to destroy harmful insects;
the nematicides - means to destroy roundworms;
fungicides - means to destroy agents of fungal diseases;
bacteriocide - remedies for bacterial diseases of plants;
blossom - means to destroy ticks;
zoocide - preparations for destroying vermin (rodents);
herbicides - means for destruction of weed vegetation;
defoliants, means for removal of leaves of plants;
deflorate - tools for removing excess of flowers and ovaries;
desicant - tools for dehydration plants;
limacina - means to destroy shellfish and slugs.
Some drugs have a broad spectrum of action and can be used as insecticides, and fungicides (insectofungicides).
Insecticides by the nature of the penetration into the body of insects are divided into several groups: intestinal - kill the insect when released into the digestive tract; contact - acting through the outer cover; fumigants - falling in a gaseous state or in the form of vapour in the respiratory tract; complex - amazing insects in different ways. In addition, there are systemic pesticides or pesticide systemic actions that after spraying their plants can easily penetrate through the leaves, and when applied to the soil through the root system inside the plant, causing the toxicity of his juices for insects to a greater or lesser period of time.
There are different ways of application of agricultural pesticides. These include: dusting or dusting plants pure chemicals present in the powdered state, or ustami - powder-like mixtures containing along with pesticide (active principle) and filler (talc, kaolin, ash), granulated preparations (granular); spraying solutions of pesticides in water or organic solvents; spraying suspensions in cases where agrochemicals in solid form not soluble in water to form in her uniform suspended particulate matter; spraying emulsions in cases where the toxic chemicals that represents the liquid, not dissolves in water, forming it a homogeneous suspension drops; application of aerosols or artificial mists and fumes; fumigation - processing gases or vapour; the use of poisoned baits.
The toxicity of pesticides is determined by their chemical structure, and physical properties. The most dangerous pesticides in the form of vapour, aerosols, gases, mist. The extent determines the degree of possible receipt pesticide vapours in the air and, consequently, in the human body through the respiratory system. Well soluble in lipids connection penetrate through the intact skin and have a predominant effect on the nervous system. Resistant to various physical and chemical influences substance (persistent connections) long time stored in the objects of the external environment and to act in a human organism with food, water etc. From soil these pesticides can move in growing tubers and roots, underground water, etc., In livestock products pesticides fall as a result of processing of animals and premises pesticides, when using a forage fodder containing residual amount of persistent pesticides.
For judgment on the toxicity of the pesticide is used most often median lethal dose (LD50), i.e., dose, caused the death of 50% of the experimental animals in a single entrance through the gastrointestinal tract. Depending on the values of LD50 pesticides are divided into four groups: 1) highly toxic substances (LD50 - up to 50 mg/kg); 2) highly toxic substances (LD50 - from 50 to 200 mg/kg); 3) srednetonnazhnye (LD50 - from 200 to 1 000 mg/kg) and 4) low-toxic (LD50 - more than 1 000 mg/kg).
The ability of a substance to koumoulirovati determines the risk of chronic poisoning. Cumulation is the ability of substances to accumulate in the body when multiple admission (material accumulation) or to cause the accumulation of pathological changes associated with multiple long-term effect of the poison (functional cumulation). For the evaluation of cumulative properties of pesticides ratio is applied cumulation is the ratio of total dose of a substance causing the death of 50% of the animals with multiple introduction to the dose, caused the death of 50% of the animals in a single injection of the drug in the body. On cumulative properties of pesticides are substances with: 1) sorkkalantie (coeff. cumulation is less than 1); 2) expressed cumulation (coeff. - from 1 to 3); 3) moderate cumulation (coeff. - from 3 to 5); 4) mild cumulation (coeff.- more than 5).
On resistance of agricultural chemicals are also divided into 4 groups: 1) very persistent that decompose toxic components than 2 years; 2) resistant to 0.5-1 year; 3) moderately persistent - 1-6 months; 4) Marostica - 1 month.
Individual chemical compounds, getting on the skin have a local irritant effect - cause local inflammation of skin and mucous membranes until ulceration, and penetrates through the skin have obscherezorbtivnymi action. Under resorptive action is toxic effect on the organism as a whole, regardless of whether called the local defeat or not. Especially dangerous are those agricultural pesticides, which do not have minoritarijami action, and absorbed through the skin, asymptomatic cause toxic effects. In this case, you should pay special attention to protection of the skin.
To prevent poisonings with pesticides and the prevention of pollution of the external environment is crucial compliance with maximum permissible concentration (MPC) in the working zone air, in water and also permissible residual quantities (PKD) in food products.
Maximum allowable concentration is considered the maximum amount of a chemical in air or water, which has no effect on people's health by prolonged intake throughout life. Permissible residual amounts in foods consider the maximum amount of a substance entering the body throughout life, does not cause any health disorders in children and adults.
The cause of intoxication may be incorrect labour organization, violation of individual protection measures and rules of personal hygiene (eating with unwashed hands, Smoking during operation), the use in food of treatment must be performed grain, seeds, pollinated vegetables and fruits.
Pathways of pesticides in the body: breathing organs, skin, gastrointestinal tract.
All products of transformation of poisons in the body excreted by the kidney, and to a lesser extent the intestines. Organochlorine substances, compounds of mercury, arsenic removed from the body very slowly, deposited in the tissues of different organs, forming depot.
The most widely used in agriculture, phosphorus, chlorine, organo-mercury compounds, preparations, arsenic, copper, derivatives karbamino acid, nitroanaline connection.

The agricultural pesticides (pesticides, insectofungicides) - chemical substances used for plant protection from harmful insects and weed control.
Depending on purpose there are: insecticides (see Dezinficiruyusch funds) - substances to destroy harmful insects; fungicides - anti fungal diseases of plants; herbicides - means for destruction of weed vegetation; acaricides - drugs destroy ticks; bactericides (see Bactericidal action) - drugs used to fight bacterial diseases of plants; zoocide - substances used to kill rodents; nematicides - the preparations for elimination round worms (nematodes); limacina - means to destroy shellfish. To agricultural pesticides also include defoliants are substances intended for removal of leaves of plants before mechanized cleaning; desiccant - preparations for pre-harvest drying plants; deflorate - the substances destroying excess ovaries and inflorescences on plants, etc.
The agricultural pesticides belong to different classes of inorganic and organic compounds. Widespread chlorine substituted hydrocarbons (DDT, HCH, polychlorine, heptachlor), phosphoric esters, thio - and dithiophosphonic acids (typos, metaphos, methylmercaptan, chlorophos, fosfamida, the drug M-81, karbofos and others); organic mercury compounds (granosan, by the beginning of which is ethylmercury), the derivative karbamino acid (sevigny, TMTD, carbin, IFC, glorify, eptam and others), derivatives chlorophenoxyacetic acid salts, esters 2-4-D, and others), derivatives of urea (dichloroacetone, Moneron, Diuron), triazine (Simazine, atrazine), inorganic compounds of barium (chloride, barium carbonate, barium)used to control pests of sugar beet and other crops; arsenic, copper (for example, Bordeaux liquid is a mixture of solutions of copper sulphate and lime milk, which is used against mange, rust of pear and Apple trees and others); iron supplements and other
On character of action on insects and other pests of plants pesticides for agriculture is conventionally divided into intestinal, contact, fumigants and system. Intestinal pesticides for agriculture affect mainly pests with chewing mouthparts, contact operate through external cover insects, fumegante - through breathing apparatus, system, easily penetrates the tissues of plants and affect pests feeding on plant juices. The majority of agricultural pesticides has not one, and several types of actions, such as organophosphorus insecticides (methylmercaptan, the drug M-81, fosfamida) are not only the products of the system actions, they share and contact action.
Drugs used in agriculture, besides the existing beginning, contain fillers, emulsifiers and other auxiliary substances.
The majority of agricultural chemicals is a poison to humans and warm-blooded animals. According to the degree of toxicity they are divided into four groups: a potent, highly toxic, srednetonnazhnye and low toxic. The basis of this classification is based on the dose causing the death of 50% of the animals at introduction of substances into the stomach (SD). Drastic agricultural pesticides are substances SD less than 50 mg/kg of body weight of the animal. SD highly toxic - from 50 to 200 mg/kg, srednetonazhnykh - from 200 to 1000 mg/kg of low - above 1000 mg/kg
When determining the degree of danger of the substance should consider not only its toxicity after a single dose in the body, but also the ability to accumulate in the body, persistence in the environment and Many other organochlorine products (DDT, HCH, polychlorine, heptachlor) have expressed cumulative properties.
Pesticides can be not only persons employed by the company for their direct application, but also people involved in care for sowing, harvesting, processing, as well as the General population due to the possible contamination of agricultural pesticides soil, feed and crops, ambient air and water bodies. In industrial conditions the majority of pesticides can enter the body in contact with them people through the respiratory system, intact skin, the gastrointestinal tract.
Organochlorine insecticides have polaroplast effect on the organism: usually affects parenchymatous organs (liver, kidneys and nervous system. Signs of poisoning of allospecific: General weakness, dizziness, nausea, irritation of mucous membranes of eyes and respiratory tract. There were cases of hypersensitivity to individual substances.
Most of organophosphorus insecticides easily enters the body through intact skin. They have a pronounced anticholinesterase action. Symptoms of acute poisoning specific: drowsiness, pupillary constriction, muscle fibrillar twitching, tremor, seizures, and other symptoms that characterize the excitation of the Central and peripheral m - and n-holinoreaguykh systems.
Action mercuroorganic fungicides associated with blocking of sulfhydryl groups thiol enzymes. Acute poisoning observed metallic taste in the mouth, gipersalivacia, headaches, nausea and sometimes vomiting, the unconscious, diarrhea with mucus, often with blood.
In severe poisoning usually occur paralysis of the extremities, hearing loss and blindness. Symptoms in the initial period, expressed little: fatigue, sleep disorders, tremor and other Additional diagnostic feature is the presence of mercury in urine.
Some carbamates effect on cholinesterase; however, unlike organophosphorus compound, is a reversible inhibition of the enzyme. Individual substances in this group have allergic action.
Pesticides used for spraying and dusting plants, seed treatment, manufacture of poisonous baits, fumigation of soil, aeration facilities and others Use them with aviation, tractor, knapsack sprayers and dusters and other


In the USSR over the use of pesticides is helpful and current sanitary supervision. Preparations are injected into the practice of agriculture only after studying their toxic properties and development of measures on prevention of poisoning. Sanitary supervision is carried out on the basis of "Sanitary rules for the storage, transportation and use of pesticides in agriculture", special instructions and rules for individual substances or types of work approved by the sanitary supervision.
To work with pesticides is not allowed teenagers under 18, pregnant and lactating women. The length of the working day when working with pesticides should not exceed 6 hours, and with potent drugs - 4 hours.
A complex of sanitary-hygienic measures aimed at the prevention of pesticide poisonings, provided: 1) replacement potent, highly toxic and persistent chemicals that can accumulate in the body and in the environment, substances, less dangerous; 2) regulation of the conditions of application of pesticides, the choice of the most secure forms and methods, improvement in view of hygienic requirements machinery and apparatus; 3) the correct organization of works on the storage, transportation and use of pesticides; 4) carrying out of preliminary and periodic medical examinations of people working with pesticides.
Contraindications to work with agricultural pesticides are: organic diseases Central nervous system, mental illness, the active form of pulmonary tuberculosis, bronchial asthma, severe forms of liver disease, gastrointestinal tract, kidney, eye, dermatitis, eczema and other
An important addition to the main activities is the use of means of individual protection (overalls, respirators and other).
In the USSR banned the use of hard organophosphorus insecticide - mercaptophos, many of the substances in this group (the preparation of M-74 and others) and organochlorine compounds of diene synthesis (Aldrin, dieldrin, endrin, Isodrin and others) are not allowed in the practice of agriculture, or their use is strictly regulated.
For widely spread in the practice of agricultural pesticides established maximum permissible concentration in the air of the working area (see table).

Maximum allowable concentrations of vapors and aerosols of agricultural chemicals in the air of working zone
Name of the substance The number, mg/m3
Aldrin
Amine salt of 2,4-D
Calcium arsenate
The calcium arsenite sodium
Atrazine
Bromide revenged
Butiphos
The gamma isomer of hexachlorocyclohexane
Hexachloran
Hexachlorobenzene
Heptachlor
Granosan (mercury)
DDT
Dinitrocatechol
Dinytrosobenzole
Dinitrophenol
Dichloroethane
Greens Paris
Carnation
Carbin
Karbofos
Mercury (mercury)
Metaphos
methylmercaptide
Methylnitrate
Naphthalene
Nitrofen
Ethylene oxide
Octamethyl
Pentachloronitrobenzene
Polychlorine
The Drug M-81
Free cyanamide
Sevigny
Sulphuric acid, sulphuric anhydride
Hydrogen sulfide
Simazine
Sulpham ammonium
Titan
Typos
TMTD
Trichlormethane-3
Trichlorophenolate copper
Formalin (formaldehyde)
Fosfamida
The zinc phosphide
Chlorophos
Horses (disulphide)
Harten
Hydrogen cyanide and salts of hydrocyanic acid
The black cyanide (in terms of HCN)
Carbon tetrachloride
ethylmercury
Avirulent
0,01
1,0
0,3
0,3
2,0
1,0
0,2
0,05
0,1
0,9
0,01
0,005
0,1
0,05
2,0
0,05
10,0
0,3
0,1
0,5
0,5
0,005
0,1
0,1
0,1
20,0
1,0
1,0
0,02
0,5
0,2
0,1
0,5
1,0
1,0
10,0
2,0
10,0
0,1
0,05
0,5
0,3
0,1
1,0
0,5
0,1
0,5
10,0
0,2
0,3
0,3
20,0
0,005
2,0

Conduct pre-hygienic assessment of machines and devices, designed to work with pesticides. The construction of large stores of agricultural chemicals is carried out on a standard project, approved by the sanitary supervision.
In many collective farms, state farms and other farms established regular brigade for the use of pesticides, whose members are trained, including in security measures. Much attention is paid to health education of the population.
In research institutions of the country, developing problems of hygienic and Toxicological assessment of pesticide (currently more than 50), learning not only toxicodynamic substances and possible carcinogenic, mutagenic, teratogenic and other properties of pesticides.