Tap chi Khoa hpc DHQGHN: Cac Khoa hoc Trai dit va Moi truong Tap 30 Sfi I (2014) 50-57 I Danh gia rui ro sue khoe doi vai van de nhiem Asen (As) nuac ngam a ph6 H6 Chi Minh Nguyen Hao Quang* Viin Ky thugt Biin 658 Vo Vdn Kiet Qudn 5, Thdnh phd Hd Chi Minh Nhan 03 thang nam 2014 Chinh sira 17 thang nam 2014; Chip nhan d ^ g 31 thang nam 2014 Tom tat: Nudc ngam tgi Thanh phfi Ho Chi Minh Uong nhung nam viia qua bi syt giam nghiem trpng tinh trang khai thac qua mtic Sy suy giam lugng nudc nglm k6o theo cac he luy khdc nhu sut liin dat, nhiem nguon nudc ngam, giam trir lugng sii dyng Trong do, d nhiem Asen gay cdc anh hudng 1cm den ngudi sir dung nguon nudc ngam tai day Dya tren ket qua quan trac danh gia chat lugng nudc ngam ciia Chi cyc Mfii trudng Thanh Ho Chi Minh nam 2011, tien hanh danh gia nii ro stic khoe dfii vdi vdn de nhiem Asen nudc ngam tren ba doi tugng la tre em, ngudi tnrcmg va ngudi gia Phirong phap, quy Uinh vd cac thong sfi tifiu chudn de tiln hanh danh gia dya tren cac tdi lieu nghien ciiu cfing bo cua cue mdi trudng Hoa Ky (EPA) Kit qua danh gia cho thay chi s6 nii ro gay ung thu cho ba ddi tugng tren Id khd thdp, ndm ngirfing gioi han chap nhan dirge, va chua gay rui ro doi vdi siic khoe ngudi sii dung Tir khoa: Nuac ngam, danh gid nii ro sue khoe, cue mfii mrong Hoa Ky, nii ro ung thu Dgt v a n de dung nudc ngdm tai TP Hd Chi Minh hien da vugt muc 600.000 m'/ngay, lugng N u d c ngdm la ngudn cung cdp nudc sinh hogt chii yeu d nhifiu qudc gia va vimg dan cu trfin the gidi Do vdy, d nhiem nudc ngdm cd anh hudng rat ldn dfin chat lugng radi trudng sdng cua ngudi Nhirng ndm gan day, chdt lugng nudc sdng va nudc ngam d khu vyc Thanh phd Hd Chi Minh (TPHCM) dang difin bien theo chifiu hudng xau hdm lugng mgt sd chat d nhiem Uong ngudn n u a c tang cao hogt dgng sinh hogt vd san xuat ciia ngudi cung nhu dnh hudng ciia cac logi nudc thai thj va cdng nghifip [1] Tinh hinh khai thdc su nudc bd cap dudi 200.000 mVngay dan den tmh trang m y e nudc dudi ddt ciia cac tdng chiia nudc cang bj thdp Sy gidm m y e nudc d cdc tang khai thdc, cimg vdi sy phat uifin nhanh cac cdng trinh xay dyng trfin mat ddt, dd gdy nen bifin dgng b l mdt dja hinh (liin ddt) xdy tgi nhifiu noi Uong khu vyc TP.HCM [2] Theo bao cao ciia Cue Y l l D y phdng - Bd Y t l (2008), hifin tai Vifit Nara sd ngudi cd nguy CO radc benh tiep xuc vdi Asen d a len tdi 17 trieu ngudi (chiira , % dan sd Viet Nam) Hien tugng nudc ngdm nhilm Asen dd cd tir lau nhung khdng d u g c difiu tra v a khuyfin ' DT: 84-933566290 E-mail:ri.nguycnri'S,gmailcom cao kjp thdi nen ngudi ddn van s u dyng cho an .\.H Quang'Tgp chi Khoa hgc DHQGHN: Cdc Khoa hpc Trdi ddt vd Mdi tnrdng Tgp 30 Sd (2014) 50-57 udng hdng ngdy ma khdng y thirc linh nguy hai tilm tang din siic khde [3] Cac mdu nudc cd dugc tir cac tning lara phan phdi nudc Uong TPHCM vd cdc gjeng d nhiing vimg phu can Nhin chung miic d nhiem Asen d TPHCM khong ddng ke Tuy nhien d nhiing khu cdng nghe del va hda chat nhu Tan Binh va Phu Nhudn, cac khu ndng nghiep tap trung nhu Gd Vdp, Hdc Mdn, Xdm Mdi, Ong Ta, Birdi Chdnh, muc nhiem Mn, sdt (Fe) tuong ddi nghifim trgng [4] Qua trinh cdng nghifip hda gia tdng, kfit hgp vdi viec mgc them nhifiu cac nha may, khu cong nghiep la nguy ca ddn din d nhilra Asen tuang lai d TPHCM nhilra nudc ngdm gdy dnh hudng dfin sue khde ngudi, va cdc ddi tugng sir dung nudc ngam Ddc bifit d nhiem Asen la nguyen nhan gay cac benh ddy siing, tang sac td, giam sdc td, ung thu da Ngoai ra, Asen khien ngudi sir dung bj rung tdc, te tay chan, rdi logn tifiu hod, xa gan, tdng huyet dp, huyet tan, thieu mau, tifiu duong, rdi logn vfi thai sdn ung thu Do dd vdn de ddnh gia nhiem, ddnh gid riii ro cda nudc ngdm ddi vdi siic khde sinh thai, sire khde ngudi Id cdn thiet de hudng ldi muc lieu phdt trien bfin vung tuong lai Phirong phap va v^t li$u nghien cuu Theo EPA quy trinh ddnh gid riii ro siic khde can lien hanh theo budc sau: Budc I: Nhdn dgng mdi nguy hai (Hazard Identification): Khao sat, ddnh gid lat ca cdc mdi nguy hgi cd kha ndng lam dnh hudng tac dOng x^u dfin ngudi hay he sinh thai, nfiu cd thi xera xet nd Uong trudng hgp nao Budc 2: Ddnh gid lieu tuang iing (DoseRespond Assessment): Khao sat ddnh gia mdi tircmg tdc giQa phoi nhiem va cac anh hudng Budc 3: Ddnh gid phoi nhilm (Exposure Assessment): Xem xet, ddnh gid nhiing hifiu biet ve mure tiep xiic vdi cdc tac nhan iing xuat tan xudt vd thdi diem Budc 4: Md ta nii ro (Risk Characterization): Xem xet ddnh gid cdch sii dung cdc thdr^ tin dii lieu de dua cac kfit ludn ve tu nhifin va phgm vi quy rad cac riii ro lir sy phai nhiem den cdc tdc nhdn iing xudt mdi Irudng [5-10] Bai vifit ndy trinh bay ket qua danh gia phcri nhiem Areenic tiep xiic vdi nudc ngam qua dudng an udng cho nhdm ddi tugng Id tre em ngudi trudng thdnh vd ngudi gid Theo td chiic bdo ve mdi trudng Hoa Ky (EPA), phan nhom doi tugng phai nhifim tren dua vao sd tudi nhu sau: i) Tre em dudi tudi; ii) Ngudi Idn khoang 30 tudi; va iii) Ngudi gia Uen 65 tuoi Ddnh gid liiu vd ddnh gid phai nhiem Tmh Tdng lilu (Total Dose) Total dose = (concentration in envir medium) * (intake rate)* (absorptionfactor) Trong dd: Concentration Id ndng dg dugc tai difim mdu, cd thfi cd cdc dan vj nhu (ppm) hay parts per billion (ppb) Thdng sd intake rate dugc ldy tir vific tinh thdi gian phai nhifim (how many years), sd lugng hdp thy (for fcmd/ingestion: bao nhifiu grams/ngay; cho nudc Id bao nhifiu lil/ngay; cho khdng la bao nhieu m^ /ngdy) vd tdn xudt la bao nhieu duration/frequency (bao nhifiu ngdy/nam; bao nhifiu gid/ngdy), phy thugc vdo dii lieu dua dfi danh gid phoi nhifim Thdng sd absorption dugc mac dinh la 10% cho cac hgp chdt hiiu ca (oral) = % for cdc hgp chdt vd ca (oral) A H Quang Tap chi Khoa hoc DHQGHN: Cdc Khoa hoc Trdi ddt vd Mdt tnrdng Tap 30 So I (2014) 50-5 Neu Id ddi vdi viec hii thd thi dugc tinh theo retention factor YIU td luu trii (Retention factor) = 50% cho sy hit thd Tdng lifiu dugc trinh bay dudi dem vi ug, hogc rag Ifdc tinh ADD - average daily dose chuyen sang dan vi Id rag per kg ciia trgng lugng ca thfi (BW) ufin a Vai riii ro ung thu Chiing ta ttnh lieu trung binh ca ddi hdng hay LADD bdng cdch tinh trung binh tdng lugng phai nhiem cd ddi Ufin mdi ngudi khodng tning bmh la 70 ndm Tuy nhien, nghien ciiu ndy, chiing ta chia Id nhdm tudi, gom tre em la tudi, ngudi trudng ihardi Id 30 tudi va ngudi gia tren 65 tudi Do do, tinh loan se chia theo nhdm doi tugng ndy dfi tinh LADD = Tdng lilu / (Sd tudi*365d/y*kgBW) b Doi vdi rui ro khdng ung thu, Chiing ta udc tinh ADD bang trung binh long lifiu cho dg dai phai nhiem: Trong trudng hgp nghien ciiu nay, tinh sd ndm phoi nhiem diing bdng sd tudi ciia tirag nhdm ADD Tdng lifiu/(sd ndm phoi nhiem*365d/y*kgBW) = mg/kg/d(or mg/kg-d) Ghi chii: ca "kg of B W vd "day" deu la cdc mdu sd vd "tdng lieu - total dose" la tit so cua cdc cong thuc trfin So sdnh kit qud vai quy chudn a Ddi vai cdc chdt gdy ung thu, Chung ta udc tmh riii ro cd ddi Risk (cdc chdt gdy ung thu) = khd ndng * lieu lugng Dfi udc tinh riii ro ung thu tir lieu hang ngdy trung binh ca ddi vdi chat ung thu nhu sau: Trong do, q la ylu td ddc nil ro (dn udng, tifip xiic) hay la dan vi yeu td riii ro (khdng khi, nudc) va cd the truy van de ddng Uen cdc ngudn online (vi du nhu IRIS) Cdn ghi nhd rang neu nhu q dugc trinh bay vdi dan vj (mg/kg/df' cho (dn), chiing ta nen chuyen nd ve dan vj (ug/l)'', de linh todn cho tilp xiic phai nhiem vcji nudc, dan vj la (ug/m3)'' cho tifip xiic khdng Tuy nhifin, cac sy chuyfin ddi chi mang tinh tuang ddi vi cac dieu kifin khdng the so sdnh dugc hay anh hudng khdng gidng vdi cac dudng ddn tniyfin phoi nhiem khdc Trong thyc tfi, khong cd mgt "quy chudn" ddi vdi riii ro Chiing ta chi udc ttnh cac tdc dgng ma dugc ludng trudc, hay cd the bi ung thu cd ddi ngudi va dugc Uinh bdy dudi dang la cdc trudng hgp trfin 10,000 hay 1,000,000 (or mg/kg-d) Vgt liiu nghien cuu Do Vifit Nam chua cd cac nghien ciiu chinh thtic vl riii ro mdi trudng, cung nhu vfi ddc hgc mdi tnrdng Do dd, cac thdng sd tieu chuan va he sd phii hgp vdi ngudi Viet Nam vdn chua cd Trfin ca sd dd, tdc gia sii dung cac thdng sd chuan de so sanh vd ddnh gia riii ro siic khde dua Uen ket qua nghifin cdu da cdng bo cua ca quan mdi trudng Hoa Ky fhttp://vmw.epa.gov/IRISA Cac sd lieu nghifin ciiu dugc liy tir sd li^u bdo cdo quan trdc chdt lugng mdi trudng cua Chi cue mdi trudng phd Hd Chi Minh ndm 2011 Dia ban ddnh gid Uen toan thdnh thdng qua 15 diem mdu nudc dudi ddt Ban dd vi Ui cdc difim mau dugc cho theo hinh I vd bdng I sau: V H Quang ,Tgp chi Khoa hpc DHQGHN: Cdc Khoa hgc Trdi ddt vd Moi truang, Tgp 30, Sd I (2014) 50-57 53 Hinh Vi tri cac tram quan trdc nuo'c diroi dat tai TP.HCM [11] Chi tiet cac dia diem quan trdc hdng ndm chdt lugng nudc ngam theo bdng sau Bang Cac diem quan trdc chat lugng nuoc ngdm hang nSm 2011 [I I] Thil Due Q.2 10 11 12 13 14 Cli Chi Phu Nhuan Hoc Mon Q.12 Binh Chanh Q.ll GdVap Tan Binh Binh Tan Q.9 Linh Xuan Thgnh MJ Lgi Thdi Tam Thfin CT Dong Thgnh Tan Phu Trung Tan Son Nhdt Tan Chanh Hiep Dfing Himg Thuan Binh Hung Phii Thg Go Vdp CV Bdu Cat Tan Tgo GdCat Long Thanh My Ky hieu LX TML TTT CTDT TPT TSN TCH DHT BH PT GV CVBC TaT GC LTM Ghi chu: Cac trgm tr6n dui?c thi^t lap d^ quan trie thudng nien ii I I S.H.lSfrmg/Tap chi Khoa hoc DHQGHN: Cdc Khoa hoc Trdi ddt vd Moi trudng Tgp30.Sd I (2014)% 6nhiem\ * \ Khdngatp Linihfona X W ^ ^ Kh6nglh|fchi»ii TtMcm^X bidg.a&o \BI«g* V \ '\ / nhiem JlEbnhii f 'Ngudn ^^ Biijvc ngSm CN.kllmlra^ tem Hinh So dfi xuong ca cho nguyen nhan gay nhiem nguon nudc ngam Ket qua nghifin cihi nguon nudc ngdm dugc xay dyng trfin bifiu dd xuang ca CED hinh 2: Xdc dinh cdc nguyen nhdn Kit qud ddnh gid riii ro De xdc dinh nguyen nhan gay nhiem nudc ngdm tgi Tp H6 Chi Minh, tac gia tien hdnh thu thap sd lieu, khao sdt thyc te vd xdy dyng bifiu xucmg cd CED Dya trfin ket qua khao sat va bilu cd thfi thay dugc cac nguyen nhan gay d nhiera, tir dd co the dua cdc hudng khac phuc cy thi Dya trfin kfit qua khao sat phdn tich dugc tai cdc trgm thu mau, thdng qua xit ly sd lieu ta cd cac bang ket qua ve hien trang Asen phd Hd Chi Minh Tra bdng tii cdc bao cao ciia EPA de tira cac thdng sd tinh todn cdn thilt rdi dua vdo cdng thiic tinh phdn mfim Excel, ta dugc cac bdng kit qud ddnh gid nii ro gdy ung thu (Bang 2) Tong quan cac nguyen nhan gay d nhiem Bang Kit qua danh gia nii ro gay ung thu ciia As ddi vdi tre em Danh gia cho Asen Dia diem CTDT LX DHT GV TSN CVBC PT TaT BH TPT TTT TCH TML LTM OCNTM As 0.003 0.002 0.003 0.008 0.002 0.008 0.008 0.009 0.01 0.004 0.006 006 0.006 0.012 0.05 Inta](e rate 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 0.61 Absorption factor 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Total dose BW 0.000183 0.000122 0.000183 0.000488 0.000122 0.000488 0.000488 0.000549 0.00061 0.000244 0.000366 0.000366 0.000366 0.000732 15.3 15.3 15.3 15.3 15.3 15.3 15.3 15.3 15.3 15.3 15.3 15.3 15.3 15.3 LADD J^ im'f^^^ 7.28206E-09 ' 1.09231E-08 2.912S2E-08 7.28206E-09 2.91282E-08 2.91282E-08 3.27693E-08 3.64103E-08 1.45641E-08 2.18462E-08 2.18462E-08 2.18462E-08 4.36924E-08 Risk slope factor ^ t.RQ J ^?nWn* 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 r!l.879E-20' 7.31SE-20 1.952E-19 4.879E-20 1.952E-19 1.952E-19 2196E-19 2.439E-19 9.7S8E-20 1.464E-19 1.464E-19 2.927E-19 y.H Quang Tgp chi Khoa hgc DHQGHN: Cdc Khoa hpc Trdi ddt vd Moi trudng Tdp 30 So (2014) 50-57 Bang Ket qua danh gia nii ro gdy ung thu cua As doi vdi ngudi trudng Danh ^ia cho Asen Dia diem CTDT LX DHT GV TSN CVBC PT TaT BH TPT TTT TCH TML LTM QCVN As Intake rate 0.003 0.002 0.003 0.008 0.002 0.008 0.008 0.009 0.01 0.004 0.006 0.006 0.006 0.012 0.05 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 Absorption factor 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Total dose BW LADD 0.00039 0.00026 0.00039 0.00104 0.00026 0.00104 0.00104 0.00117 0.0013 0.00052 0.00078 0.00078 0.00078 0.00156 71.5 71.5 71.5 71.5 71.5 71.5 71.5 71.5 71.5 71.5 71.5 71.5 71.5 71.5 4.98132E-10 3.32088E-10 4.98132E-10 1.32835E-09 3.32088E-10 1.32835E-09 1.3283 5E-09 1.4944E-09 1.66044E-09 6.64176E-10 9.96264E-10 9.96264E-10 9.96264E-10 1.99253E-09 Risk slope factor 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 RQ 3.337E-21 2.225E-21 3.337E-21 8.9E-21 2.225E-21 8.9E-21 8.9E-21 l.OOlE-20 1.112E-20 4.45E-21 6.675E-21 6.675E-21 6.675E-21 1.335E-20 Bang Ket qua danh gia riii ro gSy ung; thu ciia As doi vdi nguoi gia Danh gia cho Asen Dia diem CTDT LX DHT GV TSN CVBC PT TaT BH TPT rrr TCH TML LTM OCVN As Intake rate 0.003 0.002 0.003 0.008 0.002 0.008 0.008 0.009 0.01 0.004 0.006 0.006 0.006 0.012 0.05 1.33 1.33 1.33 1.33 1.33 1.33 1.33 1.33 1.33 1.33 1.33 1.33 1.33 1.33 Absorption factor 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Total dose BW LADD 0.000399 0.000266 0.000399 0.001064 0.000266 0.001064 0.001064 0.001197 0.00133 0.000532 0.000798 0.000798 0.000798 0.001596 70 70.7 70.7 70.7 70.7 70.7 70.7 70.7 70.7 70.7 70.7 70.7 70.7 70.7 2.37874E-10 1.58583E-10 2.37874E-10 6.3433 IE-10 1.58583E-10 6.34331E-10 6.34331E-10 7.13622E-10 7.92914E-10 3.17166E-10 4.75748E-10 4.75748E-10 4.75748E-10 9.51497E-10 So sdnh vdi quy chudn Quy chuan 09:2008/BTNMT cua Bd Tdi nguyfin Mdi trudng la quy chuan ky thuat Qudc gia vfi chat lugng nudc ngam ddi vdi Viet Nam Risk slope factor 6.7E-12 6.7E-I2 6.7E-I2 6.7E-I2 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 6.7E-12 RQ I.594E-21 1.063E-21 1.594E-21 4.25E-21 1.063E-21 4.25E-21 4.25E-21 4.781E-21 5.313E-21 2.125E-21 3.188E-21 3.188E-21 3.188E-21 6.375E-21 S6 lifiu quan trdc d tdt cd cdc dilra dfiu ndm dudi ngudng cho phfip ciia quy chudn Theo EPA, phdn chia chi sd RQ theo cdc mirc theo bdng sau: S.H Quang, Tgp chi Khoa hgc DHQGHN: Cdc Khoo hoc Trdi ddt vd \l6i tnrdng Tgp 30 Sd I (2014) 50-57 Bang Bdng phSn cap cac ngu&ng nii ro mac benh ung thu theo RQ QCVN 09:2008/ BTNMT Nguy CO m3c ung thu Rui ro mac benh ung thu thap, cd thi chap nhan Rui ro mac benh ung thu trung buih, c6 the c6 hogc khfing c6 quyet djnh giam thieu rui ro va nhung quyet djnh phai dya Uen nghien curu bd sung Riiiromac bfinh ung thu cao Nhgn xet: Chi so RQ sau tinh todn Id kha nho, tit ca cac difim raau ddi vdi nhdm tre em, n g i ^ tnrdng thdnh va ngucri gia diu cd chi sd RQ < 10"*, dd ddng nghia vdi Riii ro mdc bfinh ung thu thdp, cd thfi chap nhan Tuy nhien chi so RQ thdp nhung van cd cdc nguy ca tifim tang gdy anh hudng den siic khde ngudi, va cdc hfi sinh Ihdi d nhiing miic dp khac Bdi vi cdc thdng sd tinh ngudng la dimg cho ngudi My, chii khdng phai cho ngudi Viet Nam cd the Ugng yeu ban Ngodi ra, nghifin ciiu ndy cung chua kfit hgp vdi mdt nghien ciru sau hon vfi cdc dudng din tniyfin chdt d nhilm, bifin ddi cac chat hda hgc ciing tac dgng tfin ca the [MO] he sd khong chdc chan Cac khdng chac chan ndy gdy cho ddnh gia riii ro trd nen de ddt Cdc so lieu dugc thu thdp tir Cue mdi tnrdng Hoa Ky (USEPA) Theo Cue radi tnrdng Hoa Ky, cac ddnh gid dugc udc tinh cho ngudi My, vdi thfi trgng cao han so vdi ngudi Viet Nam Va do, lifiu lugng tdi da md ca the cd the chdp nhan dugc cua ngudi Vifit Nam ciing khac vdi ngudi My Tuy nhien, nudc ta chua cd nhimg nghifin ciiru sau ndo vfi cac vdn &e ddc hgc mdi trudng, xac dinh cac chi sd ngudng cy the nen phai tham khao ngudn tai lieu nudc ngoai Do dd, rdt cdn cd cac nghien ciru ve dgc hgc chuyen sdu dfi dua dugc cac ndng dg ngudng cho dilu kifin, hdu va ngudi Vifit Nam Ket luSn Dya tren cdc kfit qua RQ cho thay nudc ngdm trfin dia bdn todn phd c6 mirc riii ro ddi vdi sire khde thdp Trong nhihig ndm tiep, c ^ cd cac nghien ciiu sdu ban, so lugng difim ralu nhifiu han dfi danh gid chinh xdc ban dnh hudng, nii ro nudc ngdm den mdi irudng va ngucri Tac gid khdng thfi thyc hien thi nghiem tryc tilp md chi cd the sii dung kfit qua phdn tich dgc hgc tren dgng vgt giap xac (Daphnia va Cerio) vd xay dyng quan he lieu - dap iing, tii suy difin lieu thara chifiu cho ngudi qua cac Tai lieu tham khao [1] Dang Vilt Hiing Le Thi Hfing TrSn, Tidn Tuan Khanh, De xuat ke hogch cdp nucfc an loan cho nha may nuoc Tan Hiep, 2009 [2] Le Van Trung Hfi Tfing Minh Djnh LTng dung ky thudt INSAR vi phan quan tr^c bien dang m$t dat tai khu vuc dianh phi Hfi Chi Minh 2008 [3] D ^ g N g g c Chanh NguySn TrSn Bao Thanh Nguyen Do Quoc Thong Mfi hinh xu ly Arseii uong nufic ngam dp dyng cho d p ntrdc tap trung 191 xa Tan U n g huyen Thanh Binh tinh Dong Thap "'«SS*2J3?'^^''°"^^^^*-««'™^ .\'.H- Quang Tap chi Khoa hgc DHQGHS- Cdc Khoa hoc Trdi ddi vd Mdi inrdng Tap 30 Sd (2014) 50-57 [5] Canada, Environmental RiskAssessment (ERA):An Approach for Assessing and Reporting Environmental Conditions 2000 [6] EPA Guidelines for Ev-posure Assessment 1992 [7] EPA Guidelines forEcol