DEFOLIANTS (Latin the de-prefix extraction, destruction + folium a leaf) — the chemical substances intended for removal (defoliation) of leaves of plants.
Usually apply to preharvesting removal of leaves at late ripening cultivated plants.
Have toxic properties for hematothermal animals and the person. Their influence on the workers who are in contact with drugs during the performance of work on harvesting and also on the population as a result of pollution of objects of the environment and foodstuff is possible (see. Pesticides ).
As D. most widely use calcium cyanamide, free cyanamide, magnesium chlorate, chlorate-calcium chloride, butifos, a folex, sodium fluosilicate.
Calcium cyanamide (CaCN 2 ; pier. weight 80,12) — drug of contact action, its activity it is connected with education under the influence of moisture of air of free cyanamide. Affects the vasomotor and respiratory centers, irritates a mucous membrane of eyes, causing burns and conjunctivitis. At receipt inside has average toxicity (LD 50 200 — 1000 mg/kg). Through skin gets poorly, causing sometimes eczema.
Free cyanamide (H 2 CN 2 ; pier. weight 42,01) release in the form of water solution. It is toxic for hematothermal animals. At acute poisoning sharp face reddening, necks, an upper half of a body, the complicated breath is characteristic. Decrease in a hemoglobin content, change of exchange of chlorides, a leukocytosis can be observed. Strongly irritates a mucous membrane of eyes. Easily gets through the unimpaired skin.
Magnesium chlorate [Mg (ClO 3 ) 2 - 6H 2 O; pier. weight 191,21] — colourless crystal substance. Has small toxicity, does not get through skin, but dries it and causes cracks. Irritates a mucous membrane of eyes.
Chlorate-calcium chloride [Ca (ClO 3 ) 2 + CaCl 2 • 6H 2 O] represents the light yellow solution having 22 — 26% of active ingredient. Has small toxicity. At hit does not exert impact on an organism on skin. Irritates mucous membranes of eyes.
Butifos [(C 4 H 9 S) 3 PO—S,S,S — tributiltritiofosfat; pier. weight 284,2] — an oily liquid, is badly dissolved in water and it is good in organic solvents. Is issued in the form of 70% of oil solutions and emulsions. It is toxic at hit on skin, renders local irritant action. Possesses antikholinesterazny action. At acute poisoning — a severe headache, the general weakness, sharp sweating.
Folex [(C 4 H 9 S) 3 P — tributiltritnofosfit; pier. weight 308,29]. Release in the form of the emulsion containing 70 — 75% of active agent. Has a pungent smell. It is dangerous during the swallowing, inhalation and hit on skin. Has average toxicity. Irritates a mucous membrane of eyes. Poorly collects in an organism.
Sodium fluosilicate [Na 2 SiF 6 ; pier. weight 188,06] — white or grayish powder, inodorous. It is highly toxic. Gets through skin, possesses sharply expressed local action. It is often applied in combination with calcium cyanamide. At working with this mix dermatitis, changes from upper respiratory tracts were observed, a tendency to anemia.
Dignity. - a gigabyte. working conditions during the work with D. depend on extent of mechanization of the main and auxiliary operations, and also on properties of the used drugs. Under production conditions the main ways of arrival of D. to a human body are airways and skin.
At D.'s use it is necessary to carry a possibility of local action during the performance of work as the unprotected hands to number of the adverse moments or at accidental hit of splashes of solutions on face skin or in eyes.
The strongest air pollution takes place during the processing of plants calcium cyanamide, butifosy and a folex as these drugs are toxic and capable to get through skin. Working conditions with them should be considered potentially dangerous.
During the processing of plants of D. widely use aircraft that can cause pollution of free air of the inhabited places, waters, especially open reservoirs. Therefore D.'s spraying by aircraft on the sites located closer than 300 m from settlements and open reservoirs is forbidden.
At organophosphorous D.' hit on skin it is necessary to wash away immediately them water with soap. At poisoning depending on weight of a state — long atropinization and antidotal therapy. At D.'s hit on a mucous membrane of eyes it is necessary to wash out eyes a large amount of water.
the Flour particles of calcium cyanamide remaining on leaves of a cotton can cause conjunctivitis, and other drugs — systemic poisoning and focal lesions not only in the persons occupied with processing of a cotton of D. but also in those who remove cotton (especially manually). Therefore observance of terms from the last processing of D. before harvesting is important. These terms depend on stability of drugs in external environment and their toxic properties. Processing of a cotton magnesium chlorate, chlorate-calcium chloride it is necessary to stop in 6 — 12 days prior to harvesting, drugs of cyanamide — in 10 — 15 days, butifosy — in 10 days.
Special attention shall be paid on protection of a respiratory organs, skin, an eye. The people participating in preparation of solutions and loading of airplanes and tractor units D. shall work wearing spectacles (see. Points, protective ), respirators (see), special clothes (see. Clothes protective ), footwear and mittens. During the aviaprocessing signallers who shall be supplied with the special umbrellas protecting them from hit of drops of solutions, emulsions or flour particles on the person and open body parts are appointed.
Widely are implemented into practice of means of mechanization of loading and other by-works. Installation for preparation of solutions and yadosmesy UPR-150 gained distribution. Dust content of air in workplaces decreases at the same time several times.
See also Desiccants .
Bibliography: Health regulations on storage, transportation and use of pesticides (toxic chemicals) in agriculture, M., 1974; The Reference book on pesticides, under the editorship of L. I. Medvedya, Kiev, 1974, bibliogr.; L. D groans. Defoliants and desiccants, M., 1973, bibliogr.
Yu. I. Kundiyev.