DDT ndi imodzi mwa mankhwala omwe amakangana kwambiri m'mbuyomu. Zatsimikizirika kukhala zothandiza monga tizilombo, koma mphamvu yake yoopsa siyi yokha kwa tizilombo. Kuletsedwa ndi mayiko ambiri kuphatikizapo United States, DDT ndiyabe ikugwiritsidwa ntchito - mwamalamulo kapena mosavomerezeka - m'malo ena.
Kodi DDT Ndi Chiyani?
DDT, yemwenso amadziwika kuti dichloro-diphenyl-trichloroethane, ndi ya gulu la mankhwala ophera tizilombo otchedwa organochlorides.
Kachilombo kake kamene kamayenera kupangidwa mu labotale (sikuchitika m'chilengedwe), DDT ndi yosaoneka bwino, yolimba kwambiri.
DDT sangathe kusungunuka m'madzi; Komabe, zimasungunuka mosavuta mu organic solvents, mafuta kapena mafuta. Chifukwa cha chizoloŵezi chake cha kupasuka mu mafuta, DDT ikhoza kumanga mu ziphuphu zamtundu wa zinyama zomwe zimawonekera kwa izo. Izi zimagwiritsidwa ntchito kuti zitsimikizidwe, ndipo DDT imatchulidwa ndi EPA monga poizoni, yowonjezerako poizoni.
Chifukwa cha kuwonjezeka kwachilengedwe, DDT imakhalabe chakudya, kuchoka ku kansomba, achule, ndi nsomba m'matupi a nyama zomwe zimawadya. Choncho, miyezo ya DDT imakhala yapamwamba kwambiri mu matupi a nyama pafupi ndi pamwamba pa chakudya, makamaka mbalame zodyedwa ngati mphungu, mbalame, mapiri, condors ndi mbalame zina zodya nyama.
DDT imakhalanso ndi thanzi labwino pa anthu. Malinga ndi EPA, DDT imatha kuwononga chiwindi kuphatikizapo khansa ya chiwindi, mantha a ubongo, ubongo wobadwa ndi zina zovulaza.
Mbiri Yachidule ya DDT
DDT inakhazikitsidwa koyamba mu 1874, koma mpaka mu 1939, katswiri wa sayansi ya zakuthambo ku Switzerland, dzina lake Paul Hermann Müller, adazindikira kuti mphamvu yake ndi mankhwala osokoneza bongo. Chifukwa cha zimenezi, Müller anapatsidwa mphoto ya Nobel mu 1948.
DDT isanayambe, matenda opatsirana ndi tizilombo monga malungo, typhus, yellow fever, mliri wa bubonic ndi ena anapha mamiliyoni osawerengeka a anthu padziko lonse lapansi.
Panthawi ya nkhondo yachiwiri ya padziko lonse, kugwiritsa ntchito DDT kunali kofala pakati pa asilikali a ku America omwe ankafunikira kuti athetse matendawa, makamaka ku Italy komanso m'madera otentha monga South Pacific.
Pambuyo pa nkhondo yachiwiri ya padziko lonse, kugwiritsa ntchito DDT kunakula pamene alimi adapeza mphamvu zowononga tizilombo tozaulimi, ndipo DDT inakhala chida chotsatira pa kuyesayesa kwa malungo. Komabe, mitundu ina ya tizilombo inasintha ndi kukana tizilombo.
DDT, Rachel Carson ndi "Silent Spring"
Pamene kugwiritsa ntchito DDT kufalikira, asayansi ochepa adadziŵa kuti ntchito yake yopanda pake inali kuvulaza kwambiri nyama zakutchire. Malipoti obalalitsidwa ameneŵa anafika pamapeto pa buku lotchuka kwambiri la Silent Spring ndi wasayansi ndi wolemba Rachel Carson, lomwe limafotokoza kuopsa kwa ntchito yofalitsa tizilombo toyambitsa matenda. (Mutu wa mutuwu umachokera ku zotsatira DDT ndi mankhwala ena anali pa kuimba mbalame, zomwe zinatayika m'madera ena.)
Silent Spring anakhala buku logulitsa kwambiri, ndipo bukuli limatchulidwa kuti kuwonjezeka kwa kayendedwe ka zachilengedwe masiku ano. M'zaka zotsatira, asayansi padziko lonse anali kufotokoza kuti mbalame zokhala ndi DDT m'matumbo mwawo zinali kuika mazira omwe anali ndi zipolopolo zochepa kwambiri zomwe zinasweka musanayambe kuzungulira, zomwe zimachititsa kuti mbalamezo ziwonongeke.
Ndipo pamene DDT mbalame zinkakhala ndi matupi awo, zimachepetsa mazira awo.
DDT Yaletsedwa Padziko Lonse
Monga umboni wa zovulaza, DDT ikuyambitsa kukula; mayiko padziko lonse anayamba kuletsa mankhwalawa kapena kuletsa ntchito yake. Pofika chaka cha 1970, Hungary, Norway, ndi Sweden analetsa DDT, ndipo ngakhale kuti makampani a US akugwiritsa ntchito mankhwala opondereza kwambiri, ntchito ndi DDT zinaletsedwa ku United States mu 1972.
Mu 2004, mgwirizano wotchedwa Stockholm Convention on Persistent Organic Pollutants (POPs), umene unasaina ndi mayiko 170 kuphatikizapo United States, unaletsa kugwiritsa ntchito DDT ku chidziwitso cha tizilombo kosayembekezereka, mwachitsanzo, pakutha kwa mliri wa malungo. Komabe, m'mayiko ena, DDT imagwiritsidwa ntchito nthawi zonse pofuna kuyendetsa udzudzu ndi tizilombo tina, ndipo imagwiritsidwanso ntchito pa ulimi m'madera angapo monga India ndi kum'mwera kwa Sahara Africa.