Environmental Pollution 157 (2009) 396–403 Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol Relationship of urinary arsenic metabolites to intake estimates in residents of the Red River Delta, Vietnam Tetsuro Agusa a, b, Takashi Kunito c, Tu Binh Minh a, d, Pham Thi Kim Trang e, Hisato Iwata a, Pham Hung Viet e, Shinsuke Tanabe a, * a Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan Department of Legal Medicine, Shimane University Faculty of Medicine, Enya 89-1, Izumo 693-8501, Japan Department of Environmental Sciences, Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621, Japan d Department of Biology and Chemistry (BCH), City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, China e Center for Environmental Technology and Sustainable Development (CETASD), Hanoi National University, 334 Nguyen Trai Street, Thanh Xuan, Hanoi, Viet Nam b c Positive correlations between estimated arsenic intake and urinary inorganic arsenic and its metabolites were observed in human from the Red River Delta, Vietnam a r t i c l e i n f o a b s t r a c t Article history: Received 15 May 2008 Received in revised form 24 September 2008 Accepted 25 September 2008 This study investigated the status of arsenic (As) exposure from groundwater and rice, and its methylation capacity in residents from the Red River Delta, Vietnam Arsenic levels in groundwater ranged from 15 years and 15 years are considered as ‘‘adults’’ and ‘‘children’’, respectively Mean age, body height and weight, BMI, and residential years are shown in Table About 41% of all subjects were local farmers (n ¼ 40), and 32% were students (n ¼ 31) Other occupations included medical doctor (n ¼ 4), nurse (n ¼ 2), teacher (n ¼ 3), manual worker (n ¼ 5), retired worker (n ¼ 5), babysitter (n ¼ 1), public office worker (n ¼ 1), and salesclerk (n ¼ 1) All children (n ¼ 21) were students 16% and 30% of the donors have smoking and alcohol habits, respectively After collection, all samples were kept at À15 C in the freezer at the Center for Environmental Technology and Sustainable Development (CETASD), Hanoi National University After freezing at the CETASD for 2–5 days, they were transported to Japan within 24 h and were kept at À25 C in the Environmental Specimen Bank for global monitoring (es-BANK) at the Center for Marine Environmental Studies (CMES), Ehime University (Tanabe, 2006) We conducted chemical analyses within three months after the sample collection 397 (2003), arsenicals in powdered rice were extracted by Milli-Q water and methanol (1:1 v/v) Concentrations of arsenobetaine (AB), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), arsenite (AsIII), and arsenate (AsV) in urine and rice were quantified by a high performance liquid chromatograph (LC10A Series, Shimadzu, Kyoto, Japan) coupled with ICP-MS using an anion exchange column (Shodex Asahipak ES-502N 7C, 100 Â 7.6 mm i.d., Showa Denko, Tokyo, Japan) (Mandal et al., 2001) The column was equilibrated with the mobile phase (15 mM citric acid, pH 2.0 with nitric acid) at a flow rate of 1.0 mL/min at 30 C before analysis Rubidium was added to the mobile phase as an internal standard to monitor interference during analysis The injection volume was 20 mL Total As concentrations in urine and rice were represented as the sum of As compounds detected in these procedures Concentrations of total As in groundwater and As compounds in human urine have been reported in our previous studies (Agusa et al., 2005) Iron concentration in groundwater was determined by atomic absorption spectrometry (AAS) (Shimadzu AA680, Shimadzu, Kyoto, Japan) A certified reference sample NIES No 18 human urine provided by the National Institute for Environmental Studies (NIES), Japan was analyzed for confirmation of the methodological accuracy Analyzed concentrations of AB and DMA were in good agreement with the certified values with the recoveries being 90–106% (n ¼ 12) Coefficient of variance in concentrations for each arsenical was less than 2% (n ¼ 12) For quality assurance and control, we have also participated in an intercalibration exercise organized by the Swiss Federal Institute of Aquatic Science and Technology (Eawag) in the frame of the ongoing cooperation of Vietnam and Switzerland in Asrelated surveys and research Urinary creatinine level was measured by enzymatic assay consisting of consecutive enzymatic steps via creatine amidinohydrolase, sarcosine oxidase and peroxidase at SRL Inc (Tokyo, Japan) Concentrations of As compounds in urine are expressed on a creatinine basis 2.3 Statistical analyses All statistical analyses were performed with Stat View (version 5.0, SASÒ Institute, Cary, NC, USA) and SPSS (version 12.0 for Windows, SPSS Japan, Tokyo, Japan) One-half of concentration of the respective limit of detection was substituted for those values below the limit of detection and used in statistical analysis All data were tested for goodness of fit to a normal distribution with Kolmogorov–Smirnov’s one sample test Concentrations of urinary As compounds were not normally distributed, so data were log-transformed Multivariate analysis of variance (MANOVA) was used to test the effect of age, sex, and estimated As intake on the levels and compositions of urinary As species Result of MANOVA was evaluated by Wilks’ Lambda Effect of sex, age, residential year, occupation, and alcohol and smoking habits on As methylation were examined using multi-way analysis of variance (multi-way ANOVA) Tukey–Kramer post hoc test was conducted when results of multi-way ANOVA were significant A linear regression analysis was used to measure the strength of the association between estimated As intake and concentrations of urinary As compounds in human A p value of less than 0.05 was considered to indicate statistical significance 2.2 Analytical method The groundwater sample acidified with nitric acid was used for total As analysis The measurement of total As was performed with an inductively coupled plasma mass spectrometer (ICP-MS) (HP-4500, Hewlett–Packard, Avondale, PA, USA) The urine sample from subject was filtered (DISMIC-25AS-045AN, 0.45 mm, ADVANTEC, Tokyo, Japan) and diluted five times by Milli-Q water with no chemical treatment The rice was freeze-dried and then homogenized As followed by Pizarro et al Table Details of donors from Cat Que Commune, Ha Tay Province and Vinh Tru Commune, Ha Nam Province in Vietnam Location n Ageb (y) Residential periodb (y) Heightb (cm) Weightb (kg) BMIb, Cat Que Adult Female Male Childa Female 22 24 35 (16–58) 31 (16–50) 34 (3–58) 30 (2–50) 154 (143–166) 163 (153–173) 46 (37–65) 54 (44–66) 19 (16–24) 20 (17–24) 10 13 (10–15) 13 (10–15) 144 (130–160) 34 (23–44) 16 (13–17) 18 12 35 (16–63) 39 (18–60) 33 (16–63) 31 (10–58) 153 (141–163) 166 (148–179) 43 (35–50) 54 (45–62) 18 (16–22) 20 (17–23) 15 (14–15) 11 (10–13) 15 (14–15) 11 (10–13) 152 (142–168) 132 (126–142) 38 (31–48) 26 (20–34) 16 (14–18) 15 (13–20) Vinh Tru Adult Female Male Childa Female Male a b c c Resident aged 0.05) About 86% of the analyzed groundwater samples had over the guideline value (10 mg/L) established by WHO (WHO, 2004) for drinking, suggesting the possible risk of As toxicity for residents in these regions On the contrary, concentrations of As in pond water (1.5–7.2 mg/L) were quite low compared with those in groundwater Among the studies on As in groundwater from north and south Vietnam (Table 3), maximum concentration was 3050 mg/L from Gia Lam in the Red River Delta (Berg et al., 2001) Concentrations of As in groundwater from CQ and VT were much lower than those found by Berg et al (2001), but were relatively high compared with those in other studies in Vietnam (Table 3) Concentrations of As in groundwater from wells for which the depth was >15 m (mean, 240 mg/L) in VT were higher than those from shallow wells ( 15 m well depth; mean, 10.7 mg/L) A weak but significant positive correlation between As concentrations in groundwater and well depth was observed in VT (r ¼ 0.579, p < 0.05 by Spearman’s rank correlation test), implying that As 398 T Agusa et al / Environmental Pollution 157 (2009) 396–403 Table Concentrations of total As in groundwater (mg/L) and As compounds in human urine (mg/g creatinine) from Cat Que Commune, Ha Tay Province and Vinh Tru Commune, Ha Nam Province in Vietnam Location Groundwater Human urine Total As AB DMA MMA AsIII AsV SAs Cat Que na Mean S.D Min Max Median GM 13/13 209 65.5 132 344 194 200 55/56 10.1 (14.8) 12.8 (13.5)