TAP CHl HOA HOC T. 51(1)87-90 THANG 2 NAM 2013
DANH GIA HAM LlfONG NITRAT, CADIMI VA CHI TRONG RAU XANH d THANH PHd H 6 CHi MINH
Nguyen Thj Kim Phirgng'*, Nguyen Thj Minh Trang', Nguyen Thi Minh IIiV, Pham Dinh Lan^
Vien Cdng ngh? Hda hgc, Vi?n Hdn Idm Khoa hgc vd Cdng ngh? Vi?t Nam
^Khoa Cdng ngh? Hda hgc vd Thgc pham, Tnrovg Dai hoc Suphgm vd Ky thugt Tp. HCM Den Tda soan 4-12-2012
Abstract
The present study was undertaken to evaluate the concentration of nitrate (NO]'), cadium (Cd^*) and lead (Pb *) in vegetables and Ihe relationship between their conccniialion with tlie communily's health. Vegetables were random sampled from 5 various places in Linh Trung market, Thu Due district. Ho Chi Minli city. The concentration of nitrate in vegetables ranged from 205.49 to 1533 63 mg/kg of wet weight, higher than acccplcable limits of Vietnam. Average nitrate daily intake from these vegetables was quite high, however, still beyond the reference dose prescribed by the USEPA. The concentration of Cd and Pb ranged from 0 05-0.28 mg/kg wet weight and 0 03-0.15 mg/kg wet weight, respectively. Cd and Pb concenlration was lower Ihan safety limits for heavy metals in vegetables prescribed by Vietnam and FAO/WHO except Cd in bok choy and carrot Average Cd, Pb daily intake from these vegetables was much lower than the reference dose prescribed by the USEPA. Therefore, people might not have the risk of exposure to nitrate, Cd and Pb from these vegetables.
Keywords: Nitrate, cadium, lead, vegetables.
1. MO DAU
Rau xanh, cung cap cac chat dinh dudng thiet yeu cho ca the nhu: cac vitamin A, B, C cac nguyen to da, vi lugng, chat xa,... la ngudn thuc pham khong the thieu trong bira an hang ngay ciia ngudi Viet Nam.Tuy nhien, sy phat trien khdng ben virng, lam dung cac Ihudc bao ve thuc vat, chat kich thich va phan bdn hda hgc trong qua trinh canh tac da lam gia tang tich luy cac chat dgc hai Ien cac san phain ndng nghiep. Da cd cdng trinh nghien ciru chi ra rang cd sy tich luy kim loai nang va nitrat Irong san pham ndng nghiep [1, 2]. Dgc tinh cua nitrat duac hinh thanh phan ldn sinh ra tir cac phan ung sinh hoa, nitrat la nguyen nhan gay ra hgi chirng mclhemoglobin d tre em hoac sinh ra hgp chat N- nilrosoamines gay ung thu [3]. Cadimi va chi la 2 trong sd 8 kim loai gay dgc hang dSu cho sire khoe con ngudi [3]. Cadimi la nguyen to cd kha nang gay dpc ngay khi d ndng do th^p, gay rdi logn chirc nang than, tdn Ihuong xuang va rdi loan chirc nang sinh san. Chi di vao co ihk qua da, dudng tieu hoa, dudng ho h§p gay cham phat trien nh$n thirc, giam nhan thitc d fre, tang huySt ap va benh tim mgch d ngudi trirdng thanh [1]. Vi vay, tliudng xuyen giam sat h^m lugng nitrat va kim loai n^ng trong rau xanh
nham dam bao nhu cau vc thyc pham sach va an loan cho ngudi tieu diing la VIQC lam rat can thiet
Trong nghien ciru nay, chiing toi tap trung danh gia ham lugng nitrat, Cd va Pb trong mot so loai rau xanh quen thugc, udc tinh lugng nitrat, Cd va Pb an vao hang ngay nham canh bao nguy ca phoi nhiem cac chat nay lir rau xanh.
2. THUC NGHIEM 2.1. Ddi luong nghien ciiu
Cac loai rau quen thudc hang ngay
- Rau an la: cai xanh, den dd, rau lang, bd xoi, cai thia.
- Rau an cii: ca rdi, cii cai trang.
- Rau an qua; ca chua, niudp ding va dau co ve.
2.2. Dinh luong nitral, Cd va Pb trong rau xanh 2 2.1. Xir ly mdu so bg
Mdu rau xanh mdi Ihu hoach, cdn tuai dugc chgn mua ngau nhien tai 5 dja diem ciia chg Linh Trung, quan Thii Diic, Thanh phd 1 Id Chi Minh. Cac mlu dugc danh ma sd, dan nhan, v^n chuyen nhanh
TCHH, T.51(I), 2013 den phdng thi nghiem.
Tai phdng thi nghiem: Cac mau rau tuai dugc rua sach, nhe vdi nudc de loai bd bun dat va tgp chat, trang qua nudc cat 3 lan, de rao, cSt nhd, trgn deu, chia lam 2 phan:
- Phan 1: giir tuoi de dinh lugng nitrat, mdi lan phan lich 10 gam mau luai, phan tich 3 lan dgc Igp ( n - 3 ) .
- Phan 2: say khd d 60''C tir 48-72 gid, nghien min, bao quan Irong tui PE de phan tich Cd, Pb, mdi
\kn phan tich 5 gam mau khd, phan tich 3 lan dgc Igp ( n - 3 ) .
2.2.2. Djnh lirgng nitrat
- Trich li nitrat bang nudc cat ndng (65*'C), thdi gian 10 phut tren bep khuSy tir, lam ngugi, Igc.
- Djnh lugng nitrat trong djch Irt'ch ly bang phuang phap Salicylat [4], do d budc sdng 420 nm tren thiSt bi DR/2000 (HACH, My).
2.2.3. Dinh hrgngCdPb
- Vo ca hda mau theo phuang phap TCVN 4622:1994 [5].
- Djnh lugng Cd, Pb djnh lugng bang phuang phap quang phd hap thu nguyen tii tren thiet bj GBC Avanta (Uc). Gidi han phat hien cua thiet bi (LOD) khoang 0,035 ppm ddi vdi Cd va 0,200 ppm ddi vdi Pb. Gidi ban dinh lugng (LOQ) khoang 0,117 ppm doi vdi Cd va 0,667 ppm ddi vdi Pb). Do thu hdi khoang 90,25% ddi vdi Cd va 90,24% ddi vdi Pb.
2.3. U'dc tinh Iugng nitrat, Cd va Pb do con ngudi an phai hang ngay (ADD)
Theo USEPA [3], cong thirc chung de tinh W'iu lugng ddc chat dua vao ca the trung binh hang ngay ADD (Average Daily Dose) (microgam >• kg' the trgng *: ngay"') nhu sau:
Nguyin Thi Kim Phugng vd cgng su -AT (Averaging Time): Thdi gian phai nhiem trung binh (ngay).
Vdi cac gia trj:
- ED = 30 nam;
-IR = 0,2kg/bOa[6];
- EF = 52 b&a an rau mdi loai/nSm;
- B W = 51 kg (ngudi trudng thanh) [6];
- Va doi vdi chat khdng gay ung thu tuc thdi thi AT=EDx365ngay[3].
2.4. Xirly so li^u
Sir dyng phan mem Microsoft '^^ Execell® 2010 de tinh todn va thong ke.
3. KET QUA VA T H A O LUAN
3.1. H^m lu-gng nitrat, Cd va Pb trong cac mau rau xanh
Ham lugng nitrat, Cd va Pb trong rau xanh dugc trinh bay trong bang 1. Ket qua phan tich cho thay Iugng nitrat, Cd va Pb trong cac loai rau xanh khac nhau dang ke. Dieu nay cd the do dac diem sinh thai va nhu cau dinh dudng khac nhau ciia tirng loai rau.
Bdng 1 Gia trj chinh ham lugng nitrat, Cd va Pb trong rau xanh (n = 3)
ADD CxIRxEFxED
BWxAT (1)
Trong dd:
- C (Chemical Concentration): Ndng dg nitrat, Cd va Pb trong rau xanh (|ig xg"').
- IR (Ingestion Rate): Lugng rau an trong mgt ngay (g x ngay"').
- EF (Exposure Frequency): Tan suSt "phai nhiem" ngudn rau xanh (ngay x nam'').
- ED (Exposure Duration): Khoang thdi gian phai nhiem (nam).
- BW (Body Weight): Trgng lugng ca th£ (kg).
STT 1 2 3 4 5 6 7 8 9 10
Rau nghien
CLTU
Cai xanh Den do Rau lan^
Bo xoi Cai thia Ca rot Cii cai trang Ca chua Mircrp dang Dau CO ve TCVN [7]
FAO/WHO [8]
mf Nitrat 1531,66 1517,88 642,02 1454,33 1533,63 642,08 1465,42 753,11 205,49 432,84 150-500
-
A g rau tuoi Cd 0,05 0,16 0,17 0,19 0,24 0,28 0,08 0,15 0,18 0,09 0,05-0,2
0,2 Pb 0,02 0,07 0,06 0,05 0,10 0,15 0,07 0,05 0,03 0,06 0,1-0,3
0,2 Tat ca cac lo^i rau xanh nghien cuu d6u chira nitrat, Iugng nitrat trong nhdm rau an la khoang tir 642,02-1533,63 mg/kg rau tuai, cao han gidi h ^ cho phep cua Vigt Nam tir 3-10 ISn. Lugmg nitrat trong nhdm rau an la theo thii ty sau: cai thia = cai xanh = rau den dd = bd xdi > rau lang. Nitrat chiia trong cii cai trang khoang 1465,42 mg/kg rau tuai va chiia trong cu ca rot la 642,08 mg/kg rau tuai.
Lugng nitrat trong nhdm rau an trai khoang tii 205,49-753,11 mg/kg rau tuai, nhi^u nhat trong ca
TCHH, T. 51(1), 2013
chua (753,11 mg/kg rau tuai) va it nhat trong mudp dang (205,49 mg/kg rau tuai) (hinh 1).
Ham Iugng Cd trong cac mau rau xanh thay doi tir 0,05-0,28 mg/kg rau tuoi. Trong nhdm rau an la:
lugng Cd cao nhSt trong cai thia va thSp nhSt trong rau cai xanh. Lugng Cd trong ca rdt cao han cii cai trang 3,5 ISn. K6t qua trong bang 1 cho thay, Cd trong hau h6t cac mlu rau xanh chua vugt ngudng an toan quy dinh bdi Vi?t Nam va FAO/WHO ngoai trir lugng Cd trong rau cai thia va ca rot.
Ket qua d bang I va hinh 2 cho thay, lugng Pb trong cac mau rau xanh thay doi tir 0,02-0,15 mg/kg rau tuai, thap han gidi h^n cho phep ciia Vi?t Nam va FAO/WHO.
1800- 1600 1400 1200 ) 1000
Ddnh gid ham lugng nitrat, cadimi vd...
Reference Dose). Lieu lugng nen la lieu lugng dgc chat udc tinh con ngudi tiep xiic trong mgt ngay ma khdng xay ra mgt nguy ca nao doi vdi sire khde trong suot ca cugc ddi [3]. Ket qua udc tinh lugng nitrat, Cd va Pb dugc trinh bay trong bang 2.
Lugng nitrat do con ngudi an vao hang ngay tir nhirng loai rau xanh nay la rSt nhidu, tuy nhien, k6t qua trong bang 2 cho thay, lugng nitrat, Cd va Pb do con ngudi an vao hang ngay tir cac loai rau xanh nay thap han nhieu lan so vdi lieu lugng nen do USEPA quy djnh. Do dd, con ngudi chua cd nguy ca phai nhiem nitrat, Cd va Pb tir nhirng lo^i rau xanh nay.
Bdng 2: Lugng nitrat, Cd va do con ngudi an vao hang ngay
E 400
200
u
Hinh 1: Lugng nitrat trong rau xanh
Hmh 2: Lugng Cd va Pb trong rau xanh
3.2. Vdc tinh lirgng nitrat, Cd va Pb do con ngirdi an vao hang ngay
Sir dung cdng thiic neu d phan thuc nghi?m myc 3 dk udc tinh lugng nitrat, Cd va Pb do con ngudi an vao hang ngay rdi so sanh vdi lieu lugng nen (RfD:
STT 1 2 3 4 5 6 7 8 9 10
Rau nghien cuu Cai xanh Den do Rau lang Bo xoi Cai thia Carol Cu cai trang Ca chua Muop dang Dau CO ve
RfD (ig/kg/ngay
ADD ^g/kgBW/ngay Nitrat
855,72 848,02 358,69 812,52 856,82 358,72 818,71 420,75 114,81 241,82 7000'"'
Cd 0,01 0,04 0,03 0,03 0,06 0,08 0,04 0,03 0,02 0,03 3,5*'
Pb 0,03 0,09 0,09 0,11 0,13 0,16 0,04 0,08 0,10 0,05
,(.)
""USEPA [9]; ^'FAO/WHO [3].
4. K E T L U A N
Nitrat trong cac loai rau xanh thay ddi khoang tir 205,49-1533,63 mg/kg rau tuai, cao han gidi ban cho phep ciia Vi?t Nam tir 2,16-5,02 lan. Tuy nhien, lugng nitrat do con ngudi an vao hang ngay tir nhiing loai rau xanh nay thi tucrng ddi thap hem lieu lugng ngn do USEPA quy djnh. Kim loai nang trong cac loai rau xanh thay doi khoang tir 0,05-0,28 mg/kg rau tuoi doi vdi Cd va 0,03-0,15 mg/kg rau tuai doi vdi Pb, thap ban gidi han cho phep eiia Viet Nam va FAO/WHO ngoai trir lugng Cd trong cai thia va ca rdt. Lugng Cd va Pb do con ngudi an vao hang ngay tu nhun^ loai rau xanh nay thi kha thap so vdi li^u Iugng nen do USEPA quy djnh. Do dd, con ngudi chua cd nguy ca phai nhilm nitrat, Cd va Pb tir nhimg loai rau xanh ke tren.
TCHH, T.51(I), 2013 TA! Ll5U THAM K H A O
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hllp.//www.epa.gov/iris/subst/0141 .htm Cadmium (1994).
Lien h?: Nguyen Thi Kim Phirgng Vi?n Cdng ngh? Hda hgc,
Vi?n Han iam Khoa hgc va Cdng ngh^ Vi?t Nam So 1, Mac Dmh Chi, quan 1, Thanh phd Hd Chi Minh Email: [email protected].
