Ushevu Womthofu—Imiphumela Yawo Ebulalayo
‘YISIFO esingathi sína esivame kakhulu ezinganeni.’ “Usongo lwendawo ezungezile oluhamba phambili ezinganeni.” Njengoba kungenzeka uye waqagela, usongo oluchazwe lapha luyinto efanayo: ushevu womthofu.
NgokweCDC (Centers for Disease Control yaseU.S.), “izingane ngokuyinhloko ezisengozini yemiphumela ebulalayo yomthofu. Ezikhathini eziningi, ushevu womthofu usebenza buthule: izingane eziningi ezithole ushevu azinazo izimpawu. Ngakho-ke, inani elikhulu lalezimo alixilongwa noma lelashwe. . . . Akuyona nje kuphela inkinga yezingane ezihlala phakathi edolobheni noma idlanzana elihlala endaweni ehlukile. Akukho qembu lesimo sezenhlalo nezomnotho, indawo esezweni, noma umphakathi wohlanga noma isizwe esithile esisindayo.” Lombiko uyenezela: “Ukungenwa ushevu womthofu kwezingane kuyinkinga yomhlaba wonke.”
Indlela Umthofu Othinta Ngayo Izingane
Kulinganiselwa ukuthi kusukela ezigidini ezintathu kuya kwezine zezingane ezingaphansi kweminyaka eyisithupha ubudala eUnited States kuphela zinamazinga omthofu egazini lazo aphakeme ngokwanele ukukhubaza ukukhula okuvamile. Lokhu kungasho noma yini kusukela ekulahlekelweni kancane amakhono okufunda kuya ekukhubazekeni okuphelele ngokwengqondo. Uma lokho kunjalo ezweni elilodwa, amanani embulunga yonke kumelwe ukuba ayashaqisa.
EAfrika, eAsia, eMexico, naseMpumalanga Ephakathi, umthofu ngezinye izikhathi usasetshenziswa njengomuthi yilabo abangaziqapheli izingozi zawo. Usetshenziselwa ukuqeda ukusongeleka kwesisu, ukuvikela inkaba ekungenweni izifo, ngisho nanjengomuthi wokupholisa izinsini zezinsana.
Ingozi ayikhona kakhulu ukuthi izingane ziyawa futhi zibulawe ushevu womthofu. Njengoba kwaboniswa umagazini ka-1991 weFDA Consumer, ukufa kwezingane zibulawa ushevu womthofu kuye kwaba okungavamile kakhulu. Kodwa imiphumela isabulala. Umthofu uye wabizwa ngokufanelekile ngokuthi “umbulali wokukhalipha.” Umagazini iNewsweek wacaphuna esinye isikhulu sezempilo sithi: “Kunenani elikhulu kakhulu lezingane ezikuthola kunzima ukwenza umsebenzi wokuhlaziya noma ngisho ukuma emgqeni esitolo sokudla ngoba ubuchopho bazo bugcwele umthofu.”
Ezinye izimpawu zezingane ezingenwe ushevu womthofu zihlanganisa ukusheshe zicasuke, ukuqwasha, ubuhlungu besisu, ukuntuleka kwamangqamuzana abomvu egazi, nokuphazamiseka kokukhula. Isimiso sokusebenza kwezinzwa esezilimele, esihambisana nokungahlaliseki okungapheli—njengalokho kwesilwane esivalelwe ekhejini, njengoba omunye udokotela akuchaza—kungase futhi kuphawule ingane enjalo. Ezimweni ezibucayi kakhulu, ezinye izingane zingase ziquleke futhi zibe nemiqhabanyeko, futhi ngisho nalapho sezingabantu abadala, zingase ziqhubeke zihlushwa izinkinga ezingokomzwelo. Eminye yalemiphumela ingase ingapheli, kusho umholi weLead Poisoning Prevention Branch yeCDC. Kuze kube yilapho kungenziwa khona ukuxilonga okufanele, abazali ngokuvamile iyabadida imbangela yalesifo esingumshosha-phansi.
Kungani Izingane Zingavikelekile Kangaka?
Umthofu uyingozi ezinganeni ikakhulukazi ngenxa yezizathu ezimbili. Okokuqala, izingane zithintwa amazinga aphansi kakhulu omthofu kunalawo athinta abantu abadala. Njengoba ubuchopho bazo nesimiso sezinzwa kusakhula, izithinta ngokukhethekile imiphumela yomthofu. Okwesibili, ngenxa yokuziphatha nokudlala kwazo, kungokunokwenzeka kakhulu ukuba izingane zithole umthofu endaweni ezizungezile.
Ngokwesibonelo, cabangela upende ohlanganiswe nomthofu, okusewumthombo oyinhloko wokusakaza loshevu. Emazweni lapho kungokomthetho khona ukusebenzisa upende onjalo ezindlini, izenzakalo zokungenwa ushevu womthofu ngokuqinisekile ziyokwanda. Nakuba amazwe amaningi eye akwenqabela ukusetshenziswa okuthile kukapende ohlanganiswe nomthofu eminyakeni yamuva nje, lopende usatholakala ezindlini ezindala. Izindonga, izinsimbi zamafasitela, izinto zabantwana zokudlala, imibhede yezingane, kanye nempahla yasendlini konke kusenokuba nezingwengwezi zawo. Ngokwesibonelo, eUnited States umthofu olinganiselwa ezigidini ezintathu zamathani usele ezindlini ezingaba izigidi ezingu-57. Phakathi nawo-1980, izingane zaseMelika ezingaba yizigidi ezingu-13,6 ezineminyaka engaphansi kweyisikhombisa ubudala zazihlala emakhaya apendwe ngopende ohlanganiswe nomthofu. Cishe ezingaphezu kwesigidi zalezi bezinamazinga omthofu aphakeme ngokuyingozi egazini lazo.
Indawo ependwe kabushelelezi ingase ingabi nangozi. Kodwa njengoba upende uguga, uqala ukuqhekeka futhi uxebuke. Njengoba umthofu unokunambitheka okusashukela, cishe izingane ziyodla izingcwecwe zikapende. Izingane ziye zadla umthofu ezinsimbini zamafasitela ezixebukayo. Futhi lapho upende ekugcineni uba uthuli, izingane ziwuthatha ngeminwe yazo ezintweni zokudlala, phansi, nakokhaphethi—ngokungenakugwenywa usuka lapho ungene emilonyeni yazo, udlulele ethunjini elondla isisu, nasemithanjeni yegazi. Ikakhulukazi izingane eziphakathi kwezinyanga eziyisithupha neminyaka eyisithupha ezingavikelekile.
“Kudinga umthofu omncane kakhulu ukungenwa ushevu wawo,” kubhala umagazini iNewsweek. “Ingane ingase ingenwe ushevu womthofu kabucayi (amamicrogram angu-60-80 ngedeciliter elilodwa) ngokudla imilligram elilodwa lothuli lukapende womthofu—okulingana cishe nezinhlamvana ezintathu zikashukela—usuku ngalunye phakathi nesikhathi sokuba yingane.” Ukuze ingane ibe sengozini, ukudla kwayo uthuli lukapende kungalingana nje nokudla uhlamvu olulodwa lukashukela ngosuku. “Yingakho ingane ingase igule ngokumane nje ithinte njalo insimbi yefasitela bese incela isithupha sayo,” kubika iNewsweek, yenezela ngokuthi abazali “bamane abaqapheli—noma abanakukukholelwa—ukuthi uthuli olusensimbini yefasitela labo kungenzeka ngobuqili lukhubaza ingxenye yamakhono engane yabo esikhathi esizayo.”
Umthofu Nombungu
Lenkinga idlulela ngisho nasezibelethweni zomama abakhulelwe, lapho ubuchopho obukhulayo nesimiso sezinzwa sabantwana abangakazalwa singase silimale ngokufanayo. Lapho umama okhulelwe efaka umthofu emzimbeni wakhe, kungakhathaliseki ukuthi ngokudla noma ngokuphefumula, uqonda ngqó emithanjeni yegazi lakhe. Khona-ke udlulela embungwini ngenkaba. Ingane ingase ilimale isimiso sokusebenza kwezinzwa noma ibe nesilinganiso esiphansi sokuhlakanipha. “Uma owesifazane okhulelwe edla ngisho nesilinganiso esincane somthofu, ungase udlule ngeplacenta yakhe uye embungwini,” kusho omunye umlobi wezempilo. NeScience News yabika: “Ukuhlola kuye kwaveza ukuthi abesifazane abasebenza ngomthofu emafemini baba namazinga aphakeme obunyumba, ukuphuphuma kwesisu, ukuzalwa kwabantwana ngaphambi kwesikhathi nokukhubazeka abantwana abazalwa nakho.”
Obaba nabo bangenezela ezingozini ezinjalo. Umthofu emithanjeni yegazi yamadoda ungase ubangele isidoda ukuba sikhubazeke futhi singabi namandla, okungase kuvimbele ukukhulelwa noma kubangele imibungu ekhubazekile. Imibungu elinganiselwa ku-400 000 kwabesifazane baseMelika yonakaliswe umthofu kangangoba iyoba nokukhubazeka kokukhula. Njengoba ushevu womthofu uwubhadane lomhlaba wonke, inani lezingane ezingakazalwa ezithintekile kumelwe ukuba likhulu kakhulu ngempela.
Akuzona Izingane Kuphela
Ngokusobala, nabantu abadala basengozini. Ukuze bavikele izingane zabo, kumelwe bazivikele bona ngokwabo. Abavikelekile kanjani engozini yomthofu? Izazi ziyavuma ukuthi ngaphandle kukapende wendlu, umthombo obaluleke kakhulu wengozi namuhla umthofu osemanzini ngenxa yokuxhunywa kwamapayipi (njengoba ngisho namapayipi ethusi kungenzeka aye ahlanganiswa ngomthofu) nophethiloli onomthofu. Ezikoleni nasemahhovisi, imithombo yamanzi inamathange avalwe ngomthofu. Esinye isikhulu se-EPA (Environmental Protection Agency yaseU.S.) siyalinganisela: “Cishe amaphesenti angu-20 okubhekana nengozi yomthofu avela emanzini okuphuza.” IAgency for Toxic Substances and Disease Registry yamazwe onke yabika ukuthi isilinganiso somthofu “ovela eziqandisini zamanzi zikagesi singaba esiphakeme kakhulu, futhi singaveza ingozi kashevu enkulu kakhulu kubo bonke abantu, hhayi ezinganeni kuphela.”
Okunezela kulenkinga, abazali bangase balethe umthofu ekhaya ngezingubo abazigqoka endaweni yomsebenzi futhi babeke izingane zabo engozini eyengeziwe. Kuye kwalinganiselwa ukuthi cishe izisebenzi eziyizigidi eziyisishiyagalombili eUnited States iyodwa zibhekana nengozi yomthofu endaweni yazo yokusebenza. Inani elikhulu lalaba abesifazane.
Labo abagcina uphuzo oludakayo noma ezinye iziphuzo ezitsheni ezenziwe ngomthofu nabo bazifaka engozini ethile, njengoba umthofu walezinhlamvana ungase uphumele ophuzweni. Ngokufanayo, izitsha zobumba ezingazange zishiswe esilinganisweni esiphakeme ngokwanele sokushisa zingase zixebulele izilongoshana zomthofu ezisezitsheni zizifake ekudleni. Ngokwesibonelo, omunye umbhangqwana wathenga izinkomishi zekhofi lapho uhamba kwelinye izwe. Kwatholakala ukuthi lezinkomishi zazikhipha umthofu ophindwe izikhathi ezingu-300 ngaphezu kwalokho okuvunyelwa izindinganiso zezempilo ezweni lawo siqu. Lombhangqwana wagula kakhulu ngemva kokusebenzisa lezinkomishi okwesikhashana. Ngaphezu kwalokhu, umthofu osemathinini okudla, osasetshenziswa kwamanye amazwe, ubangela isilinganiso esiphansi sikashevu womthofu.
Abashisekela ukudubula nabo futhi basengozini yokungenwa ushevu womthofu. Ngani? Phela, ukuhlola kwamuva kuye kwabonisa ukuthi labo abaya njalo ezindaweni zokuqeqeshela ukudubula ezakhelwe ngaphakathi banamazinga aphakeme omthofu abawuthola ngokuhogela uthuli olunomthofu. Ukuqhuma nokudleka okungabonakali kwezinhlamvu zomthofu njengoba ziphuma emibhojeni yesibhamu kuthumela izinhlayiyana zomthofu emoyeni, futhi umdubuli uzidonsela emaphashini akhe, kubika umagazini iScience News. Ezinye zezimpawu ezibaliwe ukunambitheka kokusansimbi okungapheli kanye nokuba nedumbe lesandla elibangelwa ukuphazamiseka kwesimiso sezinzwa. Okunye ukuhlola kwabonisa ukuthi amalungu omkhaya angase futhi abe sengozini enkulu yokubhekana nengozi yomthofu ovela kwabasebenzisa izibhamu abaletha ekhaya uthuli lomthofu ezingutsheni zabo.
Njengoba ushevu womthofu uvame kakhulu futhi uyingozi kangaka ezinganeni nakubantu abadala ngokufanayo, umbuzo olandelayo usobala: Yini engenziwa ukuze uvinjelwe?
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Umzimba Ungabekezelela Umthofu Ongakanani?
ONGAKANANI umthofu omningi kakhulu? Ongakanani umzimba ongakwazi ukuwumunca ngokulondekile? Nakuba izazi zesayensi zisadingida imibuzo enjalo, amazwe amaningi aye amisa imithetho ukuze avimbele ushevu wothofu, okungenani kupende womthofu. IAustralia yashicilela umthetho onjalo ezincwadini ezingokomthetho emuva ekuqaleni kwawo-1920. IGreat Britain, iGrisi, iPoland, neSweden zamisa imithetho efanayo kamuva kuleloshumi leminyaka. IUnited States ayizange iwumise owayo Umthetho Wokuvinjelwa Kukapende Womthofu kwaze kwaba ngo-1971.
Nokho, kusukela ngalesosikhathi iUnited States iye yamisa imithetho eqine ngokuqhubekayo kulomkhakha. Ngo-1985 iCDC (Centers for Disease Control yaseU.S.) yehlisela isilinganiso somthofu esamukelekayo egazini kumamicrogram angu-25 (izingxenye ezingu-25 kweziyisigidi zegremu) omthofu ngedeciliter elilodwa legazi. Lokho kwakuyingxenye yesilinganiso somthofu udokotela omkhulu wokuhlinza ayebhekisele kuso emuva ngo-1970, okwakungamamicrogram angu-60 ngedeciliter elilodwa. Kodwa njengoba iminyaka yayidlula, ukuhlola okwengeziwe kwasikisela ukuthi izingane zingase zilinyazwe ngisho nangamazinga aphansi omthofu. Ngakho ngo-1991 iCDC yaphinda futhi yehlisa izinga elamukelekayo laba ngaphansi kwengxenye, ilehlisela kumamicrogram ayishumi ngedeciliter elilodwa.
Nakuba kunempikiswano evuthayo maqondana nokunye kokuhlola okuyisihluthulelo okwabangela lolushintsho, okunye ukuhlola kuye kwaveza imiphumela efanayo. Ngokwesibonelo, ukuhlola okubili okwenziwa eScotland kwahlanganisa amazinga omthofu egazini aphansi ngamamicrogram angu-11 ngedeciliter nokuhlakanipha okunciphile nezinkinga zokuziphatha ezinganeni. Futhi njengoba iBangkok Post yaphawula ekuqaleni ngo-1992, imithetho enjengalowo waseThailand ovikela abantu abadala emthofini ingase ingabavikeli abantwana—ikakhulukazi abangakazalwa.
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Ushevu Womthofu—Inkinga Yasendulo
UMTHOFU kungenzeka wawusetshenziswa ngasekuqaleni kwawo-3000 B.C.E. Abantu baseGibithe lasendulo babewusebenzisela ukubaza izithombe nokwenza izitsha zobumba, abasePhoenicia namaKaledi babehwebelana ngawo, futhi amaGreki aseAthene ayewumba ezimayini iminyaka engaba amakhulu ayisikhombisa. Kodwa kwakungamaRoma, phakathi nokubusa koKesari, aqala ukuthola amandla angokwezimboni omthofu—futhi ahlupheka kakhulu ngenxa yakho.
AmaRoma ayewubiza ngokuthi iplumbum. Izisebenzi ezichwepheshile zagoqa amaqeqeba amakhulu omthofu aba amapayipi anezilinganiso zobude obungu-15 ukuze ziwasebenzise ezimisweni zawo ezisabalele zokuthunyelwa kwamanzi. Kokubili amaRoma namaGreki abekela izisebenzi zamapayipi zosuku lwanamuhla isibonelo ngokuxhuma amapayipi omthofu elinye kwelinye. Kanjalo amapayipi angamakhilomitha amaningi ayengaxhunywa ukuze athwale amanzi amabanga amade. AmaRoma enza futhi izitsha zokuphuzela, izitsha zewayini, namabhodwe okupheka ngomthofu. Uphahla olwalwenziwe ngamaqeqeba omthofu lwenzelwa ukufulela.
Kodwa njengoba ukusetshenziswa komthofu kungekusha, neqiniso lokuthi ugulisa abantu aliyona into etholwe muva nje. Umagazini iScience News uyabhala: “Okungenani iminyaka engu-2 000, abantu baye baqaphela umthofu njengoshevu onamandla kakhulu kuyilapho bengayiqondi indlela owushevu ngayo.” Nokho, izikhathi eziningi amaRoma asendulo abonakala engaziqondi izingozi zangempela zomthofu. NgokukaJerome Nriagu weCanadian National Water Research Institute, ngokuvamile ayenezela ewayinini lawo uju lwamagilebhisi olwalubiliswe ezitsheni ezenziwe ngomthofu. Umagazini iNewsweek ucaphuna uNriagu ethi: “Isipuni esincane esisodwa soju lwamagilebhisi olunjalo sasiyoba esingaphezu kokwanele ukubangela ukuxhwala okuwumphumela kashevu womthofu.” Futhi abaholi bamaRoma babeliphuza kakhulu iwayini. UNriagu ulinganisela ukuthi izigwili ezingamaRoma zaziphuza ilitha elilodwa kuya kwamahlanu ewayini nsuku zonke!
“Kucatshangelwa ukuthi esinye sezizathu eziyimbangela yokuwa kombuso wamaRoma kwakuwukuthanda kwawo ukunandisa iwayini lawo ngomthofu,” kubika iMedical Post yaseCanada. Omunye umbiko uthi: “Ukuthola ushevu ekusebenziseni kakhulu izitsha zomthofu, izikhali, izimonyo, izitsha zewayini, namapayipi amanzi kungenzeka kwakube yimbangela yokuhlanya kwababusi [baseRoma] namazinga obunyumba nokuphuphuma kwezisu okwagcina izigaba ezibusayo zishiyela ukubusa kwabangebona abozalo.”
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Umthofu Ezilwaneni Zasendle
UMA uzithanda izilwane zasendle, kungase kukuphazamise ukwazi ukuthi izinyoni zasemanzini ezilinganiselwa ezigidini ezintathu ziyafa unyaka ngamunye ngenxa yoshevu womthofu. Nalapha, futhi, ushevu womthofu ubizwa ngokuthi “isifo esingabonakali” njengoba ngokuvamile sivela singaqashelwe. Umnyango Wezangaphakathi waseU.S. ubika ukuthi ngenyoni ngayinye abazingeli abaphumelelayo ukuyibulala, ingxenye yesine yekhilogremu lezinhlwayi zomthofu eziphuma ezibhamwini liphelela endaweni ezungezile. Izazi zesayensi yezinto eziphilayo ezazihlola ungwengwesi lomhlabathi amasentimitha ambalwa ngaphansi ezihlanjeni, ezizibeni nasemachibini ziye zathola kwezinye izindawo izinhlwayi zomthofu ezingaphezu kuka-250 000 ngehekthare elilodwa! Izinsimbi zomthofu zokudoba ezilahlekile zingcolisa ngaphansi.
Ngemva kokudlula kwenkathi yokuzingela, amadada nezinye izinyoni zamanzi ezifuna ukudla zigwinya lezinhlwayi. Ezinsukwini ezintathu kuya kweziyishumi kamuva, ushevu ufinyelela emithanjeni yegazi futhi udluliselwa ezithweni eziyinhloko—inhliziyo, isibindi, nezinso. Ezinsukwini ezingu-17 kuya kwezingu-21, inyoni iyaquleka bese iyafa. Izinkozi ezingenazinsiba zingathola ushevu womthofu ngokugwinya izinhlwayi zomthofu ezishutheke emizimbeni yezinyoni zamanzi ezizidlayo. Kusukela ngo-1966, ezingaphezu kuka-120 zalezinyoni eziyivelakancane ezidla inyama ziye zatholakala zifile ngenxa yokungcoliswa umthofu—ezingaphezu kwengxenye kusukela ngo-1980. Eqinisweni, lelinani limelela kuphela lezozinkozi izidumbu zazo ezahlolwa futhi kwatholwa imbangela yokufa; mhlawumbe kuyiqhezwana lengqikithi yangempela.