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Diklor–difenil–trikloretan (DDT) izuzetno je postojan i učinkovit organokloridni insekticid koji se u prvoj polovici 20. stoljeća naširoko koristio za suzbijanje vektora koji šire dizenteriju, tifus, malariju i druge bolesti. Iako je zbog izuzetno štetnog djelovanja na ljudsko zdravlje i okoliš zabranjen Stokholmskom konvencijom u većini država svijeta 2004. godine, i danas se koristi u mnogim afričkim zemljama za suzbijanje malarije jer su koristi veće od štete koju DDT uzrokuje. Procesom bioakumulacije dolazi do povećanja koncentracije rezidua DDT-a kod životinja koje se nalaze više u hranidbenom lancu. DDT je pronađen u svim sastavnicama okoliša zbog mogućnosti transporta atmosferom, a najveći utjecaj je na tla i vode. U tlu je slabo pokretljiv pa se zadržava u površinskim slojevima gdje ga apsorbiraju biljke, a time i životinje koje se njima hrane. Iz tla može ponovno ispariti i ući u atmosferu, a vrijeme poluraspada DDT-a u tlu je od pola godine do čak više od 16 godina ovisno o lokalnim uvjetima i tipu tla. Danas je najveći problem kontaminacija voda jer je DDT izrazito hidrofoban te se apsorbira u organske čestice sedimenata i time akumulira u organizme koje žive u njima. Do danas nije pronađena prikladna alternativa koja ima visoku efikasnost i širok spektar upotrebe kao što ima DDT. Dichlorodiphenyltrichloroethane (DDT) is an extremely persistent and effective organochloride insecticide that was widely used in the first half of the 20th century to control vectors that spread dysentery, typhus, malaria and other diseases. Although it was banned in most countries by the Stockholm Convention in 2004 due to its extremely harmful effects on human health and the environment, it is still used in many African countries to combat malaria because its benefits outweigh its harm. The process of bioaccumulation leads to an increase in the concentration of DDT residues in animals that are higher in the food chain. DDT is found in all the components of the environment because it can be transported by the atmosphere, and the greatest impact is on soil and water. It does not move in soil, so it remains in surface layers where it is absorbed by plants, and thus by e animals that feed on them. It can evaporate from soil again and enter the atmosphere, and the half-life of DDT in soil is from half a year to even more than 16 years depending on local conditions and soil type. Today, the biggest problem is water contamination because DDT is extremely hydrophobic, so it is absorbed byorganic sediment particles and thus accumulates in the organisms that live in them So far, no suitable alternative has been found that has as high efficiency and a wide range of use as DDT. |
