KY YEU "CAC BE TAI NGHIEN CUU KHOA HOC CONG NGHE NGANH TAI NGUYEN VA MOI TRl/ONG GIAI SOAN 2002 2006" DETAI N G H I E N C U f U X A C D j N H M 0 C D O 6 N H I E M D I O X I N T R O N G D A T V U N G[.]
KY YEU "CAC BE TAI NGHIEN CUU KHOA HOC- CONG NGHE NGANH TAI NGUYEN VA MOI TRl/ONG GIAI SOAN 2002-20 DETAI: N G H I E N CUfU X A C D j N H M C D O N H I E M D I O X I N T R O N G DAT VUNG N H l l M CHAT DOC D A CAM/DIOXIN, C U THE T A IKHU V U C BIEN H O A , T l f N G B U O C X A Y D U N G V A D E X U A T N G U O N G PHUC V U CHO GIAI PHAP KHAC PHUC • • • Co quan chu tri: Van phdng Ban Chi dao Qudc gia khac phuc hau qua chat doc hod hoc My su dung chien tranh d Viet Nam (Vdn phdng Ban Chi dao 33) C h u n h i e m de t a i Nguyin Tien Dung, Phd Chanh Van phdng Ban Chi dao 33 Can bo t h a m gia nghien c u u : TS Le KeSon ThS Pham Hong Trudng ThS Pham Gia Khanh CN Cao Thi Thu Huong KS Pham Lan Anh Van phdng Van phdng Van phdng Van phdng Van phdng Ban Ban Ban Ban Ban Chi dao 33 Chi dao 33 Chi dao 33 Chi dao 33 Chi dao 33 Muc tieu cua de tai: - Xay dung ca sa khoa hoc de de xuat nguong n h i i m doc D i o x i n m o i truong dat phuc vu nghien cuu, phuc vu cong tac tay doc tai nhung vung nhiem nang d Viet Nam - Nghien cuu, xem xet va kien nghi Thu tudng Chinh phu ban hanh ve lieu luong tdi da cho phep ddi vdi D i o x i n m d i trudng dat d Viet N a m theo ket qua nghien cdu cua de tai - De xuat cac de tai nghien cuu tiep theo de xay dung lieu luong t d i da cho phep cua Dioxin ddi vdi cac m d i trudng khac nhu: • Nude (bao gdm nude an uong, nude sinh hoat, nude thai, nude t u nhien, ); • Khdng k h i ; • Luang thuc; • Thuc pham (la ngudn thdc an va sinh sdng hang cua ngudi dan) Noi dung nghien ciru: - Didu tra nghien cdu, khao sat, danh gia hidn trang ton luu D i o x i n d vung bi d nhidm nang d mien N a m Viet Nam - Nghien cdu, danh gia va so sanh cac so lieu ve ngudng D i o x i n dat tai cac nude tren the gidi va V i e t N a m - Nghien cdu xay dung cac giai phap khoa hoc, cdng nghd de xuat ngudng Dioxin dat Viet N a m - De trinh Thu tudng Chinh phu ban hanh tieu chuan ngudng Dioxin da't nham dap dng cac hoat ddng khac phuc hau qua cha't ddc hoa hoc M y su dung chien tranh d Viet N a m , dac biet la cdng tac tay ddc khac phuc d nhidm D i o x i n m d i trudng dat 568 KY YEU "CAC DE TAI NGHIEN CUU KHOA HOC- CONG NGHE NGANH TAl NGUYEN VA MOl TRUONG GIAI DOAN 2002-2006° Tom tat ket qua nghien curu: Bao cao ket qua nghien cuu de tai dupe trinh bay theo chuong khong ke phan m d dau, ket luan va kidn nghi, phu luc va 35 van lieu tham khao CHUONG I : MUG DO NHIEM DIOXIN TRONG DAT VUNG NHIEM CHAT DOC DA CAM/DIOXIN VIET NAM 1.1 D0 TON LUU CUA DIOXIN TRONG MOI TRUONG VIET NAM Trong cac chat doc da cam ma M y da su dung 6" Viet N a m dupe san xuat vao thap ky 60 cua The k y trudc co chua tap chat D i o x i n (2,3,7,8-TCDD) v o i ham lupng dao dpng tu co ppb den ppm (cac tac gia W E Holmes va J.W.Pinson cua M y dua so lieu 0,0254 ppm) San phdm 2,4,5-T vao nhung nam dau co the chtia tur 40 dd'n 50 ppm, tham chi dd'n 100 ppm va giam xudng dd'n 0,2 ppm 2,3,7,8-TCDD vao nhung nam cudi cua thap k y 60 cua The k y X X Nhieu nha khoa hoc dua so lidu ham lupng trung binh chat Da cam la 2-3 ppm Theo sd lieu cua A H W e s t i n g va cac nha khoa hoc H p i thao Qudc te tai Tp H d Chi M i n h nam 1983 udc tinh cd 170 k g D i o x i n dupe rai xudng mien Nam Viet Nam vdi mat dp trung binh vao khoang 25 pg/g da't N h i e u nha khoa hoc cua cac nude nhu M y , Canada, L i e n bang Nga, Thuy Didn, Ha Lan, dn D p , Viet N a m , M d n g Co, H d i nghi Qudc td vd hau qua lau dai cua cac chat diet co va lam rung la cdy chien tranh Viet N a m tai Tp H o C h i M i n h t d 13 dd'n 20 thang 01 nam 1983 da thd'ng nha't nhan dinh rang k h d i lupng D i o x i n chda cac chdt diet cdy da rai d Viet Nam khdng it hon 170 k g Cung cd nha khoa hoc cho la tren 500 k g , thdm chi tren 2000 kg Sau k h i phun rai chat ddc, quan dpi M y tha bom Napalm lam chay trui rdng, dudi tac ddng cua nhiet dp cao, cha't ddc diet cay tao D i o x i n t h d ca'p va do lam tang khdi lupng D i o x i n d nhidm m d i trudng Tuong dng v d i k h d i lupng va phan bd theo vung cua cha't ddc diet cay da neu, lupng Dioxin dupe rai xudng cac tinh quanh Sai Gon vao khoang 90,1 k g ; Cac tinh N a m Trung Bp va Tay Nguydn la: 35,7 k g ; Cac tinh giap v i tuyd'n 17 la: 28,9 k g va cdc tinh ddng bang sdng Cuu L o n g la: 15,3 k g K h d i lupng rai dupe tap trung vao cac nam 1966 - 1969 Nhidu nha khoa hoc va nhidu phdng t h i nghiem cd uy t i n cua The gidi nhu phdng t h i nghiem Lien bang vd thuc pham va m d i trudng cua Cdng hoa L i e n bang Ddc; Phdng t h i nghidm Dai hoc Bach khoa Palaiseau Phap; Phong t h i nghidm cua trudng D a i hoc Ehime Nhat Ban; Phong t h i nghidm hod m d i trudng va ddc hoc D a i hoc Tdng hop Amsterdam Ha Lan; Phdng t h i nghidm cua trudng D a i hoc Remea Thuy Dien; Phong t h i nghiem A X Y S Canada; Phdng phan tich ddc hoc sinh thai V i d n han lam khoa hoc Nga d mdc dp khac nhung deu da tham gia phan tich D i o x i n t d cac mdu lay d vung da b i rai chdt dpc d mien N a m Viet N a m d Vidt N a m cung cd mdt so phdng t h i nghidm da phan tich dupe D i o x i n cac mdu tren nhu: phdng phdn tich Trung tdm Nhiet ddi Viet Nga; Phong phdn tich V H D a i hoc Qudc gia Ha N d i ; Trung tdm dich vu phan tich hoa l y Tp H d C h i M i n h ; Phdng phan tich U B 10-80 bang cac phuong phap sdc k y va sdc k y k h d i phd lien hop phan giai tha'p va phan giai cao (GC-ECD; GC-MS) 1.2 DIOXIN TRONG DAT VIET NAM D i o x i n la cha't rat dpc, rat bdn vung dieu kidn m d i trudng va tich tu chudi thdc an D i o x i n rat i t hoa tan nude va k h i xam nhap vao dat t h i no ket hop v d i 569 ^ KY YEU "CAC DE TAl NGHIEN CUU KHOA HOC- CONG NGHE NGANH TAl NGUYEN VA MOI TRUONG GIAI DOAN 2002-2 cac chat huu co bien cac phuc chat khong hoa tan nude va rai it bi rua trdi Dioxin di chuyen m o i trucmg da't rat kho khan K h i D i o x i n xam nhap vao ddt, se gay tac dpng dpc cdp tinh true tid'p ldn m i trucmg ddt va dong thoi no cung b i m o i trucmg ddt hap thu, phan ung va bidn nhung hop chdt dang keo tu l a m cho tdng ddt be mat b i chai hoa D u d i tac dpng cua anh sang, nhiet, mua, v i sinh vdt da l a m cho D i o x i n m i truong ddt b i phan huy dan theo thoi gian D i o x i n co mat m o i trudng ddt da gay tdc dpng t d i cac sinh vat cd ich, lam cho chung bi chet hoac gay nen nhung ton hai khac nhu dot bien gen d i dang cac sinh vat co l p i khong hoat dpng dupe nua da gay anh hudng rat xd'u t d i m d i trudng da't Dioxin hoan toan khdng b i phan huy sinh hoc, cac chung v i sinh thdng thudng cd mdi trudng t u nhien H i d n nay, cac nha khoa hoc dang tiep tuc nghien cuu cdc chung v i sinh dac hidu dd phan huy cac loai chat dpc k h d phan huy dd cd D i o x i n D i o x i n lam cho thuc vdt chet ddn dd'n cac loai ddng vdt cung b i chet theo khdng cd thdc an va noi cu tru Ddng thdi, D i o x i n cung tac ddng true tiep ldn dpng thuc vat ndu vdi ndng dp du ldn D i o x i n ton luu da't phu thudc vao lidu lupng, lidu lupng phun rai cang cao thi lupng D i o x i n da't lai cang nhieu va ngupc lai D i o x i n ton l u u ddt phu thudc vao cac didu kien m d i trudng nhu gid, mua, l u lut, x d i m d n mdc dp tiep xuc va su chuydn hoa cac v i sinh vat m d i trudng ddt Ham lupng D i o x i n tdc ddng manh dd'n m d i trudng dat, dac biet la k h u vuc san bay Bien Hoa - Dong N a i va vung A L u d i thupc tinh Thda Thien Hue Theo kd't qua nghien cuu cua GS L d Cao D a i vd cac cpng su, ta they dupe su thay d d i phdn cua ddt khu vuc bi nhidm cha't ddc D i o x i n dac biet la tren vung ddt nhidm Feralit K h i bi nhidm D i o x i n t h i phdn m u n cua dat bi giam xudng nhu: N i t o tdng sd chi dat gia t r i trung binh va Photspho tdng so b i giam manh, dac biet la ham lupng K a l i ngheo, ddt trd nen ngheo Photspho dd tidu D d n g thdi qua trinh trao ddi Cation k i d m thdp nhu cac Cation Ca2+, M g + trao ddi thap nhung ham lupng H + va A13+ lai tang len l a m cho m d i trudng da't trd nen chua hon N h u vay, tac ddng phun rai chat ddc hoa hoc chien tranh, D i o x i n da lam tang cudng qua trinh thodi hoa ddt, lam giam dp p h i nhidu cua ddt Kd't qua phdn tich D i o x i n mdu dat va trdm tich d mdt sd vung dac trung cua Viet N a m dupe the hidn bidu 1.3 Theo kd't qua cua Bidu 1.3 cho they ham lupng Dioxin da't cao nhat chi ton tai d k h u vuc san bay Bien Hoa, n o i trudc day da dupe quan dpi M y sd dung lam kho chda chdt ddc hoa hoc va cung la bai rua may bay sau m d i phi vu phun rai chat ddc hod hoc, vay lupng D i o x i n tich tu cac tang ddt thudng rat cao, gay ddc cho m d i trudng xung quanh Trong qua trinh nghien cdu anh hudng cua chat dpc hoa hoc M y sd dung chien tranh ldn m d i trudng dd't d Viet N a m , da cd nhidu nha khoa hoc va ngoai nude tie'n hanh t d rat sdm Nhung mdu phan tich sdm nhat vao nam 1981 cua K O l i e (Ha Lan) da phat hidn thdy ddt Rung Sat Tp H o C h i M i n h d dp sau t d 1-150 c m cd chda t d 1-31 ppt Dioxin Sau dd, vao nhung nam t d 1984 dd'n 1990 cac nha khoa hoc Nhat Ban M.Matsuda va cdng su trudng D a i hoc Ehime va A.Schecter, H Y T o n g cua M y cdng tac v d i cac nha 570 KY YEU "CAC DE TAl NGHIEN CUU KHOA HOC- C6NG NGHE NGANH TAl NGUYEN VA MOl TRUONG GIAI DOAN 2002-2006" khoa hoc cua U y ban 10-80 ( U B 10-80) da lay va phan tich 121 m l u dat va bun song cua dia phuong va song khac cua midn N a m Viet N a m , co 25 mau den nam 1990 v i n phat hien D i o x i n v d i ham luong 30-40 ppt, cao nhat la 59 ppt, ca biet co m i u bun l i n g rach T h i Nghe cao den 120 ppt T u nam 1995 den nam 2000 mot sd co quan Viet N a m nhu Trung tam Nhiet ddi Viet - Nga, U y ban 10-80, phong t h i nghiem H V - Dai hoc Qudc gia Ha N o i , co su hop tac v d i Cdng ty t u van H a t f i e l d , Canada (Hatfield Consultants Ltd.) va V i e n Han lam Khoa hoc Nga da phan tich 255 m i u dat d cac tinh D o n g N a i , Binh Duong, Tay Ninh, Thda Thien Hue, (Bang 4) Trong dat d cac sau t d 10cm den 30cm da phat hien t h i y D i o x i n vdi nong trung binh la 17,16 ppt d cac phdng t h i nghiem tren cung da phat hien t h i y ham luong D i o x i n bun l i n g d cac song D o n g N a i (khu vuc Bien Hoa), song Cai (Nha Trang), vinh Nha Trang, ho Bien H u n g (Bien Hoa), ho Go V i p (Tp.Ho Chi M i n h ) cd ham luong D i o x i n trung binh la 10 ppt C i n luu y la d cac khu vuc lan can cac didm nong nhu san bay Bien Hoa, Trung tam Nhiet ddi Viet - Nga da la'y va phan tich 13 m i u vao nam 1998 va da phat hien t h i y ham lupng D i o x i n trung binh la: 62,4 ppt Dioxin da't la nguon true tiep va thudng xuyen lam nhidm dpc m o i trudng va ngudi, doi hoi phai danh gia mpt each t i my dd co thd tra l d i cau hdi dp tdn luu cua Dioxin d Viet Nam sau hon 30 nam t d k h i kd't thuc chien tranh la bao nhidu ? Theo so lidu ma chiing tdi cd dupe, dd'n cac co quan cua Viet Nam da phan tich tren 1000 m i u d i t , bun l i n g (trong dd rieng Trung tam Nhiet ddi Viet - Nga la 700 m i u ) va da khao sat h i u nhu tat ca cac tinh bi rai va cung phan tich mpt so m i u cua midn Bac dd ddi chdng Nhin chung, ham lupng D i o x i n d i t d mien N a m Vidt N a m da giam ra't nhieu so vdi luc mdi rai ban dau, nha't la nhung viing bi phun rai nhe lai cd dieu kidn rda trdi va phan huy tu nhien cao t h i ham lupng D i o x i n khdng l o ngai Cac nha khoa hoc Matsuda, Hoang D i n h Cau va cdng su cdng trinh ciia m i n h da gop phan cho su danh gia nay; Cu thd, cac tac gia da phan tich 54 m i u d Tay N i n h chi phat hien 14 m i u cd 2,3,7,8-TCDD (14/54), tuong tu d Phu Ldc - Thda Thien Hue la 3/6, ddng bang sdng Cuu Long la 0/26, Sdng Be la 1/1, Tp H d C h i M i n h la 2/9 H a m lupng 2,3,7,8-TCDD 14 m i u d Tay N i n h dao ddng tu 1,2 dd'n 38,5 ppt, trung binh la 14,0 ppt; 04 m i u d Phu Ldc cd ham lupng 2,3,7,8-TCDD t d 4,4 - 17,0 va trung binh la 8,6 ppt; 01 m i u d Sdng Be cd ham lupng 2,3,7,8-TCDD la 6,0 ppt; 02 m i u d Tp H d C h i M i n h cd ham lupng 2,3,7,8-TCDD la 36 va 59 ppt N h u vay, chi cd khoang 19% so m i u phan tich cd phat hien dupe 2,3,7,8-TCDD va cac m i u da phat hien ndi chung deu d mdc cho phep so vdi tieu c h u i n cua M y , chi t r u vai ba m i u ca biet Tuy nhien, d nhung vung da b i phun rai nhidu l i n ca biet v i n cdn cd m i u cd ham lupng D i o x i n cao hon mdc cho phep va nhat la d nhung vung tang t r u cha't dpc hoa hoc cu cua M y v i n cdn tdn l u u v d i ham lupng cao va rat cao can dupe x d ly M d t dieu cung can quan tam la lupng D i o x i n thd cap tdn luu d mien N a m Viet Nam Nha hoa hoc Buu H d i da khang dinh bao cao ciia m i n h vao nam 1971 la d nhiet dp cao 2,4,5-T tao 2,3,7,8-TCDD Cu the hon, nam 1977 A h l i n g va ddng nghidp cho r i n g d nhiet dp 500 - 580oC, cac ester cua 2,4,5-T tao 2,3,7,8-TCDD v d i ham iupng 0,2 0,3 mg/kg, nhu vay 24.000 tan 2,4,5-T da phun rai d mien N a m Viet N a m cd thd tao 4,8 - 72 kg 2.3.7,8-TCDD Trong thuc te, sau k h i rai cha't ddc lam cay k h d heo, quan dpi M y da tha bom Napalm de dot trui day la dieu kien de tao ndn D i o x i n thd ca'p X a D d n 571 KY YEU "CAC OE TAI NGHIEN CUU KHOA HOC- CONG NGHE NGANH TAI NGUYEN VA Mni TRUONG GIAI BOAN 2002-20 Thuan, huyen Trang Bang, tinh Tay N i n h la mot t h i du didn hinh ve van dd Ket qua xet nghiem 38 m i u dat a vung cho gia t r i T E Q thap nhat la 1,37 ppt, cao n h i t la 27,78 ppt, trung b i n h la 6,8 ppt, d t i t ca cac m i u deu phat hien PCDD va PCDF (17 dong phan doc), co 18 m i u phat hien dupe 2,3,7,8-TCDD va 1,2,3,7,8-PeCDD (cac dong phan doc n h i t ) va t i t ca cac m i u deu phat hien t h i y O C D D v o i ham luotig cao t u 453 - 14.216 ppt, day la dau hieu dac trung cho D i o x i n thu c i p Cung khong rieng g i D o n Thuan, ma O C D D phat hien tha'y o h i u het cac m i u phan tich a cac vung rung nui da tirng bi rai c h i t doc hoa hoc va sau la c h i t chay, nhidu cong trinh da xac dinh ham luong OCDD va H p C D D cao la dac trung cua cac san pham cua su chay bao g o m chay cac c h i t ton du cua cac cha't diet cay V i n de ben vung cua D i o x i n - chu k y ban phan huy da duoc nhieu nha nghien cuu chii y va neu nhung phat hien cua m i n h nhidu cong trinh khoa hoc Nhidu nha khoa hoc tren the gidi cho r i n g chu ky ban phan huy cua D i o x i n chi d mdc dp nha't dinh Theo Hpi nghi khoa hoc Qudc te nam 1983 tai Tp H d C h i M i n h , chu k y ban phan huy dat la 10 nam T u y vay, cung cd nhung tac gia cho r i n g - 3,5 nam va nhu vay thi dd'n nam 1990 chi k g D i o x i n d Viet N a m , dieu la khdng phu hop vdi thuc te Qua nhidu nghien cuu vao nhung nam 90 cua the k y X X , nhieu nha khoa hoc cho la chu ky ban phan huy cua D i o x i n d i t cd thd la tren 20 nam, Theo Paustenbach D.J (1992) va Puri R K (1989, 1990) thi chu ky ban phan huy cua 2,3,7,8-TCDD d i t d ldp be mat la 0,1 cm thi dao dpng t d den 25 nam va d cac ldp da't sau hon cd thd dat tdi 25 den 100 nam Chu ky ban phan huy ciia D i o x i n co thd ddng vat la n g i n va thay ddi theo loai Theo so lieu H p i thao Qudc te tai Tp H d C h i M i n h nam 1983 t h i thdi gian ban phin huy ddng vat ndi chung khoang nam, nhung d ddng vat gam nha'm nho cdn nhanh hon Cd tai lieu cho r i n g d chupt nhat la 16 - 37 (Rose, 1996), v d i ca t d m khoang t h i n g , vdi ngudi khoang - nam Chu ky ban phan huy cua D i o x i n dpng vat va ngudi v i n la va'n de chua thd'ng n h i t Can cd tren nhung so lieu phan tich tren 1000 m i u dat d V i d t N a m va mdt so khao sat d san bay Ta Bat A L u d i ciia U y Ban 10-80 phd'i hop v d i trudng Dai hoc Ehime Nhat Ban va A X Y S Canada da ndi len phan nao vd chu ky ban phan huy cua D i o x i n d i t khdng phai la nam dd'n nam rudi hoac 10 nam ma cdn lau hon nua Kd't qua phan tich cua cac tac gia tren d ciing mdt dia didm neu tren cho tha'y m i u l i y nam 1990 d dp sau cm cd gia tri 8,5 va 17 ppt (trung binh 12,75 ppt); Cdn m i u lay vao nam 1999 cd cac gia tri: 4,3; 5,9; 7,7; 8,4; 9,2; 9,4; 9,9; 11,0; 18,35 ppt (trung binh la 9,35 ppt), sau gan 10 nam ma gia t r i khdng thay ddi dang kd gi Chu chuyen ciia D i o x i n theo chieu sau va be rdng d i t la mdt va'n dd khd nghien cuu Su di chuydn cua D i o x i n tren mat dat, theo ddng nude, theo khdng k h i la dieu hidn nhien khdng cd g i phai ban cai nhieu Kd't qua k h i o sat d i t , bun l i n g d xa Chanh M y tai Thi xa Thu Dau M d t - tinh Binh Duong, sdng T h i Nghe - Tp H d C h i M i n h , vinh Nha Trang - tinh Khanh Hoa la cac noi khdng true tiep bi phun rai c h i t dpc hoa hoc nhung ddu phat hien thay 2,3,7,8-TCDD tuong dng la 5,1 - 14,5; 59,0; ppt vao nhung nam cua thap ky 90 cua t h e k y X X Su di chuydn cua D i o x i n theo chieu sau t h i phdc tap hon va can nghien cdu k y v i dang cd nhieu y kidn khac N h i d u nha khoa hoc tren the gidi cho r i n g D i o x i n chi 572 KY YEU "CAC BE TAI NGHIEN CUU KHOA HOC- CONG NGHE NGANH TAl NGUYEN VA MOl TRUONG GIAI BOAN 2002-2006" tham sau xudng da't den 30 cm va nong dp cua chiing thudng tap trung d dp sau - 10 cm va do cac m i u d i t duoc la'y de phan tich thudng d cac ldp dat t d den 30 cm Tuy vay, phan cua d i t , dac biet la p h i n huu co da't nhu axid H u m i c g i u vai tro quan trpng viec tham sau cua D i o x i n vao da't D d truyen lan cua D i o x i n giam k h i tang ham lupng huu co dat, tdc dp d i chuyen cua D i o x i n sau xudng dat trung binh gan cm/nam (10 cm/12 nam) Ket qua khao sat cua Trung tam Nhiet ddi Viet - Nga d dia didm cua nhung vung da bi nhidm dpc chien tranh d cac tinh Dong N a i , D a Nang, Binh Duong, Tay N i n h cho tha'y D i o x i n tinh chat cua d i t co the di chuydn theo chieu sau den 2,5 m Cac khao sat tren day cho tha'y D i o x i n (2,3,7,8-TCDD) cd kha nang d i chuydn theo chieu sau khong phai chi den 20 - 30 c m ma co thd den hang met, dieu phu thupc vao chat lupng cua da't, dac biet ia ham lupng m i m va set dat, ham lupng m u n va set tha'p dat se lam tang kha nang tham sau cua D i o x i n xudng dat Theo ket q u i nghien cdu thdi gian qua co thd dua mpt sd nhan dinh sau: - Mdc dp nhidm D i o x i n quan dpi M y su dung chien tranh d Viet N a m la mdc nhidm cao nha't the gidi, theo thdi gian va dieu kien k h i hau nhidt ddi i m Viet N a m thi nong dp Dioxin da g i i m nhieu nhung v i n cao hon mdc nen cua nhidu nude tren the gidi Tuy vay, d nhung dia didm ma trudc day la co sd kho tang cu cua quan dpi M y ma nha't la khu vuc san bay Bien Hoa va Da Nang, vin dang ton l u u D i o x i n v d i ndng dp rat cao va dd D i o x i n chien tranh v i n la mdt v i n dd c i n g i i i quyet - Dp bdn vung cua D i o x i n da't la rat lau, dd chu k y ban phan huy cua Dioxin da't se dai hon nhieu so v d i cac kd't luan trudc day cua nhieu nha khoa hoc, tham chi cd the dai hon 20 nam - Su di chuydn cua D i o x i n da't theo chidu sau d Viet N a m tai nhung vung b i nhidm ddc khdng phai chi dd'n ldp d i t sau 20 - 30 cm ma cdn sau hon nhieu, cd thd dd'n 2,5 m - Dioxin thd cap dupe tao nen dot chay bang Napalm sau k h i rdng cay bi chdt chat dpc hoa hoc diet cay la didu cd thd cha'p nhan dupe Vd lupng D i o x i n cd l i n chat ddc hoa hoc Quan dpi M y sd dung chien tranh Viet Nam, cd mdt so y kien khac Theo US Department o f Health and Human Services cd 170 k g ; theo J M Stellman cd 366 kg (Nature so 1442, 4/2003) va theo cac nha khoa hoc ciia Trung tam nhiet ddi Viet - Nga cd dd'n gan 1000 k g (bdi v i dioxin khdng chi cd cha't da cam ma cdn cd cac chat ddc hoa hoc khac da dupe sd dung chien tranh Vidt Nam) Dd xac dinh lupng dioxin dat ciia nhung vung b i rai, cac t i e g i i cua Trung t i m Nhiet ddi Viet - Nga da udc tinh ndng dp T C D D trung binh d cac vung bi r i i theo thdi gian v d i gia thidt thdi gian b i n huy cua 2,3,7,8- T C D D dat la 10 nam 1 Cac kd't q u i tinh t o i n tren kha phu hop v d i cac kd't qua phan tich ham lupng 2,3,7,8 T C D D d cac vung bi rai qua cac thdi gian 573 KY YEU "CAC Pg TAI NGHIEN CUU KHOA HOC- CONG NGHg NGANH TAI NGUYEN VA MOl TRUONG GIAI DOAN 2002-20 C H U O N G II : N H I E M DIOXIN T R O N G D A T K H U V U C S A N B A Y BIEN H O A II VAN DE NHIEM DIOXIN TRONG DAT KHU VUC SAN BAY BIEN HOA San bay Bien Hoa theo nhieu tai lieu nghien cuu da khdng d i n h khu vuc la mpt nhung "didm nong" n h i i m cha't dpc Da cam/Dioxin da dupe xac dinh d Viet Nam dua theo bao cao ket qua nghien cuu cua cac tac gia Viet N a m nhu: GS Tran Xuan Thu, TS N g u y i n V a n M i n h , TS N g u y i n Xuan Net, ciing nhu cac nha nghien ciru M y va nudc ngoai nhu: GS A n o l d Schecter, Theo ket qua cua cac nghien cuu t h i nong dp D i o x i n d viing "didm nong" Bien Hoa co thd len t d i 1.000 ldn so vdi nong dp tieu chuan cho phep da't va hang tram lan so vdi tieu chudn cho phep d co thd ngudi va cac dpng, thuc vat Do v^y, viec x u l y triet dd vung da't ton luu chdt dpc Da c a m / D i o x i n d sdn bay Bien Hoa la rat can thiet va mang tinh bde xiic cao IL2 CAC PHUONG PHAP X l T L Y HUU HIEU CHAT DOC D I O X I N TRONG M O I TRUONG DAT K H U VUC SAN B A Y BIEN HOA Cac nha khoa hoc the gidi da nghien cdu nhieu phuong phap x u l y D i o x i n nhu: phan huy nhiet bang cac 16 ddt cd nhiet dp ldn hon 1.200oC, su dung cdc tdc nhan hoa hoc dd phan huy, declo hod va oxy hod v d i su co mat cua cac cha't xuc tac, phan huy bang v i sinh vat, ch6n la'p co kidm soat, Trong thdi gian qua, nhieu nha khoa hoc Viet N a m da tap trung nghidn cuu mpt sd phuong phap chinh tdy dpc D i o x i n sau day: • Phuang phap quang hoa; • Phuang phap hoa hoc; • Phuang phap sinh hoc; • Phuong phap co lap; II.3 G I A I PHAP X U X Y TRIET DE VUNG DAT TON LUU D I O X I N S A N B A Y BIEN HOA Giai phap kha thi dd x u l y Dioxin d nhung khu vuc n h i i m nang cha't Da cam/Dioxin d san bay Bien Hoa: T d nhung phan tich da trinh bay d tren ddng thdi cung chu y den nhung didu kien kinh te va xa hpi cua Viet N a m noi chung va cua vung Bien Hoa - D o n g N a i noi rieng cho tha'y co giai phap kha thi nhat, la: - CO LAP TRIET DE: Phuang phap su dung vat lieu each ly HDPE va vat lieu lpc E N V I R O M A T dd co lap da't n h i i m D i o x i n Phuong phap cho phep each l y hoan toan chat dpc D i o x i n v d i m o i trudng - CO LAP TICH CI/C: Giai phap la su ket hop phuang phap co lap vdi phuong phap sinh hoc N h u vay, qua trinh chon lap, chat dpc vdn dupe phan huy bdi cac v i sinh vat Theo thdi gian, nong dp cha't dpc se giam ddn va co thd giam den nong dp ngudng cua D i o x i n cho phep dat Giai phap la kha thi nha't, chi p h i tha'p nhat dong th6i cung doi hoi cong nghe va cac thiet bi phdc tap nha't Tren day la mpt sd giai phap huu hieu nha't nham tay dpc D i o x i n m o i trudng da't, dac biet ddi v d i phuang phap x u l y triet dd cha't dpc D i o x i n noi chung va cu 574 KY YEU "CAC 0£ TAl NGHIEN CUU KHOA HpC- CONG NGHE NGANH TAl NGUYEN VA MOl TRLfONG GIAI BOAN 2002-2006' the ddi vdi vung dat ton luu chat ddc Da cam/Dioxin d san bay Bien Hoa cdn cd mdt nghien cdu t i m i hon de danh gia thuc trang va quy m d "didm ndng" tai san bay Bien Hoa nham dd phuong an tay ddc tdi uu D i o x i n tai day CHlfONG III: OE XUAT NGUCfNG DIOXIN TRONG DAT VIET NAM PHUC VU GlAl PHAP KHAC PHUC III GlQl H A N CHIU DUNG CUA CO THE CON NGUOI D O I V O l D I O X I N D i o x i n gdm cac nhom chat (kd ca nhom chat tuong t u D i o x i n ) bao gdm: Polychlorinated Dibenzofuran (PCDF), Polychlorinated Dibenzo-para-dioxin (PCDD) va nhom chat tuong t u D i o x i n , dong phan cua Polychlorinated Biphenyl (ddng phan cua PCB) cung la D i o x i n Con ngudi tiep nhan ddc chat D i o x i n vao co thd t d cac dudng an uong, tiep xdc qua da va hit thd Theo T d chdc Y te The gidi ( W H O ) , bao cao nghien cdu vao nam 1998, thi tren 90% lupng chat D i o x i n di vao co thd la qua dudng an uong nhu: rau qua, thuc phdm va ddt bdn nhidm D i o x i n Thdng sd dac trung thudng dupe su dung la T D I (Bieu thi lidu lupng cho phep ngudi cd thd tiep nhan vao hang ngay) tdc la tai gia t r i dd bdt ddu cd thd gay hai cho ngudi Thdng sd dupe xac dinh bang phuong phap danh gid rui ro, thiet lap m d i quan he giua lupng ddc chat vao co the va r u i ro (thdng qua nguy co gay ung thu) III.2 GlQl THIEU VE TIEU CHUAN DIOXIN TRONG DAT MOT SO NUC-C TREN THE G l l Al NEW ZEALAND Tieu chudn hidn tai ciia New Zealand la 1500 (ng T E Q / k g trpng lupng khd) dupe rut td hudng ddn vd x u l y , che bien gd Bp Y te va Bp M o i trudng N e w Zealand cdng b d nam 1997, tieu chuan mang tinh tam thdi Gia tri 1500 (ng TEQ/kg) dupe xay dung thdng qua danh gia rui ro, lay vdi thdng sd T D I = 10 (pg T E Q / k g trpng lupng co the/ ngay) Tuy nhien, thdng sd se dupe thay the bdi lieu lupng hap thu ldn nhdt mdt thang la 30 (pg T E Q / k g trpng luang co the/ thdng) dupe Bp Y td cua New Zealand dua vao nam 2002, tuang duang vdi 1/10 gid t r i cua T D I hudng ddn ve che bien gd BI CONG HOA LIEN BANG Dl?C Phap ldnh cua L i d n bang Ddc (ban hanh nam 1999) ve bao vd dat va cac khu vuc d nhidm dua nhung "gid t r i hanh ddng" xua't phat t d muc tieu chinh la bao vd sdc khoe ngudi: • Da't khu vuc vui chai: 100 • Da't khu vuc dan cu: 1.000 • Dat cdng vien va khu v u i choi giai t r i : 1.000 • Da't su dung cho cdng nghiep va muc dich thuang m a i : 10.000 (don v i , ng I - T E Q / k g vat chat khd) 575 KY YEU "CAC BE TAI NGHIEN CUU KHOA HOC- CONG NGHE NGANH TAI NGUYEN VA MOl TRUONG GIAI BOAN 2002-20 Nhung "Gia t r i hanh dpng" dupe xay dung tren co so hap thu true tiep cua co thd doi v d i D i o x i n CI NHAT BAN Chinh phu Nhat Ban ban hanh tieu chuan D i o x i n m o i trudng da't la 1000 (ng T E Q / kg), tham sd nghien cuu la 250 (ng T E Q / kg) (Bp M d i trudng Nhat ban, 2001) Neu ndng dp D i o x i n dat vupt qua tham so nghien cdu t h i can tie'n hanh dieu tra Tieu chudn da cu the hoa Dieu cua Luat lien quan t d i cac bidn phap dac biet chdng lai D i o x i n (Luat ve D i o x i n ) , nam 1999 Gia t r i tidu chuan dupe xay dung xuat phat t d muc tieu bao ve sdc khoe ngudi va thuc ddy cac chinh sach cdn thidt, tinh toan tren co sd hap thu true tiep t d D i o x i n da't vao co the N o dupe ap dung vdi dat khu dan cu va ke ca v d i da't ndng nghiep, da't cong nghidp (Takabatake, pers com) K h i mdc dp nhidm D i o x i n da't vupt qua tidu chudn tren t h i theo quy dinh cua Luat ve Dioxin: Chinh quyen dia phuong budc phai cd cac bien phap khdc phuc gom ca vide x u ly, loai bd D i o x i n da't Dl CANADA Cac chinh sach ve D i o x i n cua Canada dupe xay dung trdn co sd su phan loai Dioxin theo cap dp dpc Cue Bao ve m d i trudng cua nude dua H d i ddng dieu hanh cac va'n de m d i trudng cua Canada ( C C M E ) ban hanh hudng ddn ve cha't lupng da't vdi da't d va ddt cdng viPn la (ng T E Q / k g ) ( C C M E , 2001) Gid t r i tren cung dupe dp dung vdi ddt ndng nghiep, cdng nghidp vd da't cho muc dich thuang mai, de thay the cho hudng ddn tam thdi vao nam 1991; Gia udng dat cho tha'y cam nhat v i the ma tri (ng T E Q / k g ) duoc coi la ndng dp nen trung binh cua D i o x i n m d i trtren toan lanh thd Canada V d i da't d va dat cdng vien, phan tich su phai nhidm gia tri lieu lupng hap thu hang udc tinh ( E D I ) v d i nhung ddi tupng nhay (theo C C M E ) cao hon lieu lupng hap thu hang cd thd gay hai ( T D I ) , chinh Chinh phu nude khdng cho phep lam ndng dp D i o x i n d mdc ndn tang them; Van ban hudng ddn trdn cung ghi nhan: tieu chuan D i o x i n dat duoc xem xet d cap dp quan l y chung hon la tiep can t d khia canh bao ve m d i trudng va sdc khoe cua ngudi, bdi v i tieu chudn khdng dupe xay dung td can cd la nhung anh hudng cua D i o x i n tdi m d i trudng va ngudi Nhung gia cua T D I va E D I m d i trudng t u nhien, mdc dp m d i trucmg xung quanh va nguy ca lien quan dupe xem la mdc dp nhd nha't El MY Cue quan ly chai luong moi trudng cua Bang Michigan Cue quan l y chat lupng m d i trudng Bang M i c h i g a n dat g i d i han cua cac cha't d nhidm ddt, bao gdm ca D i o x i n (DEQ, 1998) Nhung tieu chuan vd tiep xiic true tiep dupe xay dung dua vao ndng dp khdng gay anh hudng cd hai t d i sdc khoe cua ngudi Sd dung he so r u i ro gay ung thu la 1:100.000 t h i tieu chudn tiep xuc true tiep la 90 ng TEQ/kg cho tat ca cac TCDDs va PCDFs, ddi v d i dat d Cue Quan ly Chat dpc va Thd'ng ke Benh tat (A 576 TSDR) KY YEU "CAC OE TAl NGHIEN CUll KHOA HOC- CONG NGHE NGANH TAI NGUYEN VA MOl TRUONG GIAI DOAN 2002-2006° Muc dp ngan ngua can cu vao rui ro nho nhat (MRL) la pg/kg trpnglupng co thd/ ddi vdi 2,3,7,8- T C D D (theo tiep xiic true tiep) K h i nong dp vupt qua 50 ng T E Q / k g thi can phai co nhung danh gia cu thi "Nhung muc dp danh gia" co tinh toi he sd sinh hoc, mdc an uong, co che lan truyen, dp bao phu cua dat, cpng dong lien quan, mdc dp phai n h i i m nen K h i mdc dp n h i i m D i o x i n dat vupt qua 1.000 ng T E Q / k g t h i viec giam sat, nghien cuu, dieu tra ve sdc khoe can dupe thuc hien " M d c dp hanh dpng" la 1.000 ng TEQ/kg dupe xay dung dua vao nhung nghien cdu cua K i m b r o u g h t (1984) III.3 DE XUAT TIEU CHUAN DIOXIN TRONG MOI TRUONG DAT VIET NAM Dua vao ket qua nghien cdu t d Nhat Ban, M y va nhung quy dinh hien hanh cua nhung nude (da dupe trinh bay cu the tai phan gidi thieu tieu chudn cua cac nude va can cd khoa hoc xay dung ngudng D i o x i n da't), dd dac biet dua tren mhurnh tong hop ket qua da nghien cuu ve dpc hoc va dich te hoc cd lien quan de'n T C D D va su phai nhiem tiem dn m d i trucmg ddt, de tdi dd de xudt tieu chudn tam thdi D i o x i n da't d Viet N a m va cac bien phap x d ly tuang ung nham ngan ngda anh hudng cua cha't dpc len sdc khoe cdng ddng D o n g thdi, de tai cung dua trdn cac ket qua nghien cuu tren ddng vat da the hien mdc dp anh hudng ldn cd lien quan dd'n su phoi nhidm D i o x i n bao gdm: t u vong, ung thu va hoai td, cung nhu cac benh ve gan, he m i d n dich than k i n h , sinh san va anh hudng den su phat tridn Dong thdi, dd tai cung dua tren mdt so kd't qua nghien cdu anh hudng phai nhidm D i o x i n len ngudi cua cdc tac gia va ngoai nude da cdng bd De xua't tidu chudn tam thdi D i o x i n dat d Viet N a m dupe gidi han pham v i vung d nhidm D i o x i n ndm khu dan cu, cu thd nhu sau: Mdc 1: Mdc gidi han cho phep ham luong Dioxin khu dan cu la < 50 (ng TEQ/kg) va mdc = 50 (ng TEQ/kg) la MlfC CAN NGAN NGlfA Tai budc cdn xem xet va danh gia lai mdt each dinh lupng cac mdu da't ddi v d i tdng vung cu thd va so sanh vdi gidi han cho phep cua ham lupng D i o x i n , ddng thdi cd su quan tam nhieu t d i sdc khoe cdng ddng cung nhu cac m d i lidn ket vdi cac dpc to khac cd vung ngoai D i o x i n Mdc 2: Mdc gidi han ham lupng Dioxin td >50 den 1.000 (ng TEQ/kg) Xlf LY, LOAI day dupe goi la BO VA DI Rdl DAN RA KHOI VUNG NHIEM NANG Trong budc nay, cac hoat dong y te can phai tien hanh ngay, cu t h i la giam sat, dieu tra, nghidn cuu sue khoe, giao due cong dong, dieu tra phoi n h i i m , dong thdi danh gia, khoanh viing khu vuc n h i i m d i t i m bien phap x u l y , tay doc hoac di rdi dan khoi k h u vuc n h i i m nang ("diem ndng") nham ngan ngda phoi n h i i m anh hudng den sdc khoe cdng ddng dan cu N h u vay, de xua't tam thdi gidi han tieu chudn cho phep D i o x i n da't khu vuc dan cu cd gia t r i ve bao vd sdc khoe cho cdng ddng va phd'i hop chat che v d i cac thdng tin khac ve nguy co phoi n h i i m t d da't cu tru va cac trudng hop phoi nhidm cu tru Chung ta ghi nhan gia t r i ( T E Q ) < 50 ppt (0,05 ppb) > 0,05 ppb nhung < ppb va > ppb d da't cu tru, la cac gia t r i hudng ddn nham bao vd sdc khoe cdng ddng dan cu, de nhung bien phap lam sach m d i trudng k h u d n h i i m D i o x i n ddt cu t r u tai nhdng khu vuc cu the nhu cac "diem ndng" d cdc san bay: Bien Hoa, Da Nang, Phu Cat, A So Vide udc tinh cac gia t r i ham lupng tieu chudn D i o x i n dat dan cu neu tren la dua vao nhung kd't qua nghien cdu chi tiet cua cac chuyen gia sdc khoe tai Co quan quan ly chdt ddc va thd'ng ke bdnh tdt (ATSDR) cua M y da ban hanh t d nam 1989, cung nhu dupe To chdc Y te The gidi ( W H O ) va Chuang trinh Qudc te ve ngudn an toan hod hoc (Ahlborg ciing cpng su 1994) va nhieu nhom nghien cdu khac xac dinh chat gay n h i i m va nguy co tiem an ddi v d i sdc khoe ngudi cd lidn quan tai cac k h u d n h i i m nghiem trpng Dioxin Trong dd, cd neu ve gidi han ham lupng 50 ppt (0,05 ppb) T C D D , tuang ddng v d i 50 ppt (0,05 ppb) T E Q phoi n h i i m t d ddt Lupng hod chdt duac coi la ngudng xay phoi n h i i m la ppb T C D D dat cu tru (do K i m b r o u g h va cdng su de xuat nam 1984) Kd't luan dupe rut t d vide xac dinh chat T C D D gay t i i m dn can benh ung thu T d dd ppb tdng lupng D i o x i n (TEQ) ddt da dupe sd dung nhu la gidi han tidu chudn D i o x i n cho phep phai hanh dpng cua Co quan quan l y dpc hoc va thd'ng ke bdnh tat cua M y ( A T S D R ) KET KUAN Kd't qua cua de tai "Nghien cuu xac dinh mdc dp d n h i i m D i o x i n ddt vung n h i i m chdt ddc Da cam/Dioxin, cu the tai khu vuc Bidn Hoa, tdng budc xay dung va ® xudt ngudng phuc vu cho giai phap khdc phuc" da xac dinh duoc ham lupng D i o x i n cao tai mdt so "didm ndng" nhu khu vuc xung quanh cdc san bay: Bien Hoa, Da Nang, Phil Cat, A So Dong thdi cung so sanh ham lupng D i o x i n tai nhung " d i d m ndng" vdi mdt so vung khac tren lanh thd midn N a m Viet N a m cd ham lupng D i o x i n khdng cao dd tha'y dupe su phan b d khdng ddng ddu ham lupng D i o x i n ddt d N a m V i e t N a m va khoanh dupe nhung khu vuc nhidm v d i ham lupng cao D i o x i n dupe g p i la " d i d m ndng" Dd tai cung da tdng hop dupe hau he't cac kd't qua phdn tich ham lupng Dioxin dat d midn N a m V i e t N a m cua cac tac gia va ngoai nude nghien cuu t d trudc dd'n (nam 2005) Tai mpt so "didm ndng" n h i i m D i o x i n , dd tai da thd'ng ke so sanh dd tha'y duoc su phan b d ham lupng D i o x i n da't theo chieu sau tai mdt so "didm 578 KY YEU "CAC DE TAl NGHIEN CUU KHOA HOC- CONG NGHE NGANH TAI NGUYEN VA MOl TRUONG GIAI DOAN 2002-2006" nong" T h i du dien hinh nghien cuu tai khu vuc "diem nong" san bay Da Nang cua Bo Qudc phdng nam 2004 cho tha'y: • Ham luong D i o x i n trung binh trdn ldp da't 30 cm rat l d n , gap hang tram lan ndng dp cho phep D i o x i n khdng chi cd tren be mat ma lan toa xudng sau; Cu the d dp sau 150 cm ham lupng D i o x i n trung binh cua diem lay m i u v i n cao (951 ppt) • Ham lupng trung binh cua 2,4-D va 2,4,5-T d k h u vuc san bay Da N i n g la r i t cao, vupt gidi han cho phep t d 64 dd'n 1368 l i n • Ham lupng D i o x i n va c h i t Da cam cd su phan b d khdng ddng deu tai k h u vuc san bay D i NSng, nhung chiing deu giam theo chieu sau Dieu n d i len m d i quan he huu co giua ham lupng c h i t ddc Da cam va ham lupng D i o x i n dat Kd't qua nghidn cuu ve su phan b d c h i t ddc Da cam va 2,3,7,8-TCDD theo chieu sau tai c i c "didm ndng" d cac khu vuc san bay Bien Hoa va Da N i n g dupe bidu didn tren Hinh 4.1 (dua tren kd't qua cua TS Nguydn Xuan Net, Trung tam Nhiet ddi Viet - Nga, 12-2001 trong: "Tdng quan ve dp ton luu cua D i o x i n tai cac k h u vuc da nghien cuu d midn Nam Viet Nam") Dd t i i da dua vao kd't qua nghien cuu cua cac nude tren the g i d i , dd dac biet td Nhat Ban, M y va nhung quy dinh hidn h i n h cua nhung nude (da dupe trinh bay cu the tai p h i n gidi thieu tidu chuan cua cac nude va can c d khoa hoc xay dung ngudng Dioxin d i t ) dd xua't ngudng D i o x i n d i t d Viet N a m va cac bien phap tay ddc tuong dng nhu sau: Mdc 1: Mdc gidi han cho phep ham luong Dioxin khu dan cu la < 50 TEQ/kg) va mdc = 50 (ng TEQ/kg) la mdc can ngan ngita Mdc 2: Mdc gidi han ham luong Dioxin tir >50 den 1.000 (ng TEQ/kg) diy dugc goi la va la Ml?C CAN CO BIEN PHAP Xlf LY, LOAI BO VA DI Rdl KHOI VUNG NHl£M DAN RA NANG De t i i cung da dac biet quan tam dd'n "didm ndng" d nhidm v d i ham lupng cao Dioxin tai khu vuc san bay Bien Hoa, da he thd'ng h o i c i c kd't qua nghien cuu ham lupng Dioxin d i t tai k h u vuc san bay Bien Hoa cua cac t i c gia va ngoai nude; Ddng thdi dd mdt so bidn phap tay ddc cho khu vuc va c i n thidt phai cd phuong i n d i r d i d i n khoi vung nhidm dpc nang D i o x i n d khu vuc s i n bay Bidn Hoa va cac vung phu can KIEN NGHI Qua kd't qua nghidn cdu cua Dd tai "Nghien cdu xac dinh mdc dp d nhidm D i o x i n da't vung nhidm cha't dpc Da cam/Dioxin, cu thd tai k h u vuc Bidn Hoa, tdng budc xay dung va de xua't ngudng phuc vu cho giai phap khac phuc" x i n cd m i y kidn nghi sau: Chinh phu can ban hanh "Tidu chuan tam thdi cua D i o x i n cac loai d i t d Viet N a m " nham lam can cd d i n h gia hidu qua vide x d l y 579 KY YgU "CACflgTAI NGHIEN CUU KHOA HOC- CONG NGHg NGANH TAI NGUYEN VA MOl TRUONG GIAI BOAN 2002-20 D i o x i n cac k h u vuc n h i i m doc nang Trong giai doan hien tai, x i n de nghi chap nhan muc tieu chuan tam thoi ma De tai da de xudt lam tieu chuan D i o x i n d i t cu tru d Viet Nam va cac bien phap x u l y tuong dng nhu sau: Mdc 1: Muc gidi han cho phep ham luong Dioxin khu TEQ/kg) va mdc = 50 (ng TEQ/kg) la mdc can ngan ngtia dan cu la < 50 (ng Mdc 2: Mdc gidi han ham luong Dioxin tir >50 den 1.000 (ng TEQ/kg) day dupe gpi la CAN CO BIEN PHAP X l f L Y , LOAI BO VA DI Rdl DAN RA NANG Tai mpt sd khu vuc ma De tai da xac dinh la "diem n o n g " cd mdc dp n h i i m D i o x i n cao dat nhu cac "diem nong" tai cac san bay Bien Hoa, D a Nang, Phu Cat, A So Chinh phu cdn sdm phe duyet D u an x u ly tay dpc D i o x i n tai day va to chdc di rdi dan khoi khu nhiem dpc nang D i o x i n Trudc het, tai cac "diem nong" can co mpt sd bien phap han che, chdng lan toa chat dpc m o i trudng xung quanh nham bao dam an toan cho ngudi va m d i trudng khu vuc Kien nghi Chinh phu phe duyet nam 2006 hai D u an: • " X u ly khu nhidm chdt ddc hoa hoc chda Dioxin ("didm ndng" ) d san bay Bien Hoa" • " X u ly khu nhidm chat ddc hoa hoc chda Dioxin ("diem ndng") d san bay Da Nang" Kien nghi Thu tudng Chinh phu cho phep lap: Co quan quan ly dpc hoc thupc Bp Y te nham quan ly cac chat dpc phat sinh va dd cac bidn phap bao dam sdc khoe cho cpng ddng dan cu 580 ... ke phan m d dau, ket luan va kidn nghi, phu luc va 35 van lieu tham khao CHUONG I : MUG DO NHIEM DIOXIN TRONG DAT VUNG NHIEM CHAT DOC DA CAM /DIOXIN VIET NAM 1.1 D0 TON LUU CUA DIOXIN TRONG MOI... ve bao vd dat va cac khu vuc d nhidm dua nhung "gid t r i hanh ddng" xua''t phat t d muc tieu chinh la bao vd sdc khoe ngudi: • Da'' t khu vuc vui chai: 100 • Da'' t khu vuc dan cu: 1.000 • Dat cdng... ddc Da cam /Dioxin, cu the tai khu vuc Bidn Hoa, tdng budc xay dung va ® xudt ngudng phuc vu cho giai phap khdc phuc" da xac dinh duoc ham lupng D i o x i n cao tai mdt so "didm ndng" nhu khu