Environmental Arsenic Exposure and Human Health in the Mekong River Basin of Cambodia

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4 th International Forum on Sustainable Future in Asia 4 th NIES International Forum, 23-24 January 2019, Hanoi, Vietnam Environmental Arsenic Exposure and Human Health in the Mekong River Basin of

1 4 th International Forum on Sustainable Future in Asia 4 th NIES International Forum, January 2019, Hanoi, Vietnam Environmental Arsenic Exposure and Human Health in the Mekong River Basin of Cambodia Kongkea Phan Faculty of Science and Technology, International University, Phnom Penh, Cambodia International Environmental Research Institute, Gwangju Institute of Science and Technology, Gwangju , Republic of Korea 3 Cambodian Chemical Society, Phnom Penh, Cambodia

2 Content 1) Groundwater drinking pathway 2) Daily food consumption (foodstuffs) 3) Groundwater and rice

Introduction Land area: 181,035 km 2 Total population (2015): 15,578,000 GDP per Capita: 1,218$ (2015) Boundary: Thailand and Lao PDR on the West and the North Viet Nam on the East and the

3 Introduction Land area: 181,035 km 2 Total population (2015): 15,578,000 GDP per Capita: 1,218$ (2015) Boundary: Thailand and Lao PDR on the West and the North Viet Nam on the East and the Southeast. The Gulf of Thailand on the Southeast 80% of Cambodian populations live in rural areas (NISC, 2012) 28.5% of populations are living under the national poverty line in 2010 (WFP, 2012)

4 Introduction 1) Abundance and Hazard of arsenic Oxidation state: -3, 0, +3 and +5 (WHO, 2004) Well-known mineral: Realga (As 4 S 4 ), orpiment (As 2 S 3 ), arsenolite (As 2 O 3 ), loelingite (FeAs 2 ) and arsenopyrite (FeAsS) Abundant in shale, coal and ore deposits Contamination: Natural processes and anthropogenic activities Acute toxicity: Gastrointestinal discomfort, abdominal pain, vomiting, diarrhea, bloody urine, shock, Coma and death ( mg, 1-3 mgaskg -1 ) Chronic exposure: Dermatological manifestation (pigmentation, melanosis and hyperkeratosis), skin cancer, lung cancer and cancer of urinary bladder.

main source for drinking although many people live

5 40% of the total populations CANNOT access to improved drinking water sources (UNICEF, 2012) Groundwater is the main source for drinking although many people live alongside surface waters Groundwater arsenic-affected area (RDI, 2012)

6 (Polizzotto et al., 2008) (Polizzotto et al., 2007) Source of arsenic release to ground water in Asia

7 This study aims to provide a comprehensive investigation and the magnitude of arsenic exposure pathways in the Mekong River basin of Cambodia. 1) Assess health risk of arsenic from groundwater drinking pathway 2) Assess health risk of arsenic intake from local food consumption

8 Figure 1 Map of sampling sites

10 HEALTH RISK ASSESSMENT MODEL As w IR EF ED AT BW ADD = (1) ADD: Average daily dose from ingestion (mg kg -1 d -1 ) As w : Arsenic concentration in water (mg L -1 ) IR: Water ingestion rate (L d -1 ) EF: Exposure Frequency (d yr -1 ) ED: Exposure Duration (yr) AT: Average time/life expectancy (d) BW: Body weight (kg) ADD RfD HQ = (2) HQ: Hazard Quotient (Risk is considered occurring if HQ > 1.00) RfD: Oral reference dose of total inorganic As (RfD = mg kg -1 d -1 ) R = 1- exp (-SF ADD) (3) Where SF = 1.5 (mg kg -1 d -1 ) -1 is a slope factor of As for carcinogen USEPA (Integrated Risk Information System (IRIS): arsenic, inorganic, CASRN , 1998)

released to groundwater in reducing conditions As (III) Parti_As As(V) Kg

12 Groundwater chemistry Base Arsenic is released from solid phase to pore water through desorption process enhanced by alkaline condition Acid Arsenic is released to groundwater in reducing conditions As (III) Parti_As As(V) Kg Cham Reducing Kratie Oxidizing Kandal 0% 20% 40% 60% 80% 100% Arsenic Concentration

13 Table 2.8 Percentage of residents exposed to toxic and carcinogenic effects in each of the study areas (%) Cancer Risk Probability (R) Study area HQ > 1.00 > 1 in 10 2 > 1 in 10 3 > 1 in 10 4 > 1 in 10 6 Kandal (n = 297) Kratie (n = 89) Kampong Cham (n = 184) HQ: Hazard Quotient; R: Carcinogenic risk probability 1 in 10,000 is the highest safe standard for carcinogenic risk 1 in 1,000,000 is the safe standard for carcinogenic risk

1) Residents in the Kandal province study area might be exposed to more toxic and carcinogenic risks than those of the Kratie and Kampong Cham province study areas.

14 1) Residents in the Kandal province study area might be exposed to more toxic and carcinogenic risks than those of the Kratie and Kampong Cham province study areas. 2) Positive significant correlations between arsenic content in hair (As h ), arsenic levels in groundwater (As w ), and individual average daily doses (ADD) of arsenic was found

rice 10 10 10 30 Cooked rice 10 10 10 30 Vegetable 15 9 15 39 Fish 10 10 10 30

15 2) Study areas & fieldwork (Foodstuffs) Table 3.1 Number of foodstuff samples Sample Kandal Kratie Kampong Cham total Uncooked rice Cooked rice Vegetable Fish Total All foodstuffs were washed with deionized water and dried at 50 o C over night before digestion

16 Correlation of arsenic in paddy soil and rice 0.7 Total As in paddy rice (µg g -1 ) Kandal Kampong Cham Maximum level for As in raw rice 0.3 µg g -1 (FAO, 2012) r s (14) = 0.826, p < 0.01 There is a significant positive correlation between arsenic in paddy soil and paddy rice Total As in paddy soils (mg kg -1 ) Table 3.2 A comparison of the total arsenic concentrations in paddy soil (mg kg -1 ) and paddy rice (µg g -1 ) in Kandal (n = 8) and Kampong Cham (n = 8) Variables Mean ± SD Median Range t df p Paddy soil Kandal ± Kampong Cham ± Paddy rice Kandal ± Kampong Cham ± The t and df were adjusted because variances were not equal, SD: Standard deviation

17 5 [As]tot in rice (µg g -1 ) Uncooked rice Cooked rice [As] tot in fish (µg g -1 ) Kandal Kratie Kampong Cham Study area Snakehead Catfish [As] tot in vegetable (µg g -1 ) Kandal Kratie Kampong Cham Study area Cucumber Gourd Papaya Pumpkin Tomato Kandal Kratie Kampong Cham Study area Table 3.4 One-Way Analysis of Variance comparing regional groups on the total arsenic concentrations in uncooked rice, cooked rice, fish and vegetable Sources df SS MS F p Uncooked rice Between Groups Within Groups Total Cooked rice Between Groups Within Groups Total Fish Between Groups Within Groups Total Vegetable Between Groups Within Groups Total df: degree of freedom; SS: sum of squares; MS: mean square

18 Table 3.5 Summary of [As] tot (µg g -1 ), [As] i (µg g -1 ), daily intake (µg d -1 ) and daily dose (µg kg -1 d -1 )of inorganic arsenic concentration in each of the study areas Kandal Kratie Kampong Cham Foodstuffs Mean ± SD Median Range Mean ± SD Median Range Mean ± SD Median Range Rice [As] tot ± ± ± [As] i ± ± ± Daily intake ± ± ± Daily dose ± ± ± Fish [As] tot ± ± ± [As] i ± ± ± Daily intake ± ± ± Daily dose ± ± ± Vegetable [As] tot ± ± ± [As] i ± ± ± Daily intake ± ± ± Daily dose ± ± ± All (Foods) Daily intake ± ± ± Daily dose ± ± ± Inorganic arsenic was assumed to be 10% in fish, 80% in rice and 70% in vegetable. The daily consumption rates of fish, rice and fruit vegetable were g d -1, 450 g d -1 and g d -1 respectively. The average body weight of Cambodia residents was 52 kg. BMDL 0.5 = 3.0 µg kg -1 d -1

3) Study area (Groundwater & rice) Map of the sampling site Table 4.1 Summary of arsenic concentrations in groundwater (µg L -1 ), rice (µg g -1 ) and fingernail (µg g -1 ).

19 3) Study area (Groundwater & rice) Map of the sampling site Table 4.1 Summary of arsenic concentrations in groundwater (µg L -1 ), rice (µg g -1 ) and fingernail (µg g -1 ). Arsenic concentration Statistics Groundwater Rice Fingernail N Mean Median SD Min Max SD, standard deviation; Min, minimum; Max, maximum

20 Table 4.2 Summary of inorganic arsenic concentration, daily intake and daily dose of inorganic arsenic from groundwater and rice Groundwater Rice Mean ± SD Median Range Mean ± SD Median Range Inorg-As concentration ± ± Daily intake (µg d -1 ) ± ± Daily dose (µg kg -1 d -1 ) ± ± SD, standard deviation BMDL 0.5 = 3.0 µg kg -1 d -1

21 As concentration in fingernail (µg g -1 ) Arsenic toxicity As concentration in fingernail (µg g -1 ) Arsenic toxicity Daily dose of As from groundwater (µg kg -1 d -1 ) Daily dose of As from rice (µg kg -1 d -1 ) As concentration in fingernail (µg g -1 ) BMDL 0.5 (3.0 µg d -1 kg -1 body wt) Arsenic toxicity As concentration in fingernail is positive significant associated to daily dose of As from groundwater (Spearman s rho, p < 0.05) As concentration in fingernail is positively associated to daily dose of As from rice, but not statistically significant. There is positive significant correlation between the As concentration in fingernail and daily dose of total inorganic As (Spearman s rho, p < 0.05) Total daily dose of inorganic As (µg kg -1 d -1 )

22 Table 4.3 Inter-correlation between As concentrations in groundwater, rice, fingernail, daily dose of As from groundwater, rice and daily dose of total As Variables Rice Fingernail Groundwater intake Rice intake Total intake Groundwater ** * ** ** Rice ** ** ** Fingernail ** ** Groundwater intake ** Rice intake ** *p < 0.05; **p < ) The daily dose of inorganic As of Prey Veng residents was greater than the lower limits on the benchmark dose for a 0.5% increased incidence of lung cancer (BMDL 0.5 equals to 3.0 µg d -1 kg -1 body wt.). 2) Positive significant correlations between groundwater As concentration, daily dose of As from groundwater and daily dose of total inorganic As with As concentration in fingernail were found.

23 Arsenicosis patients in Kandal province, Cambodia

24 Conclusions 1) Residents in the highly contaminated study area of Kandal are exposed to more toxic and carcinogenic risks than those in the Kratie and Kampong Cham provinces. 2) The results indicate that arsenic accumulation in Cambodian residents bodies is mainly through groundwater drinking pathway 3) The daily dose of inorganic arsenic of the residents in Kandal province is higher than the lower limits on the benchmark dose for a 0.5% increased incidence of lung cancer (BMDL 0.5 equals to 3.0 µg kg -1 d -1 ) 4) Arsenic in rice is an additional source which is attributed to high arsenic accumulation in the residents bodies in the Mekong River basin of Cambodia

25 Publications

26 Ongoing work

31 Acknowledgement

32 Thank you for your attention! Q & Kongkea Phan, MSc, PhD Dean of Faculty of Science and Technology International University, Phnom Penh 12101, Cambodia Tel: phan.kongkea@iu.edu.kh A???

A review of environmental contaminations and health in Cambodia

Conference on Sustainable Agriculture in Cambodia 27-29 August 2018, Siem Reap, Cambodia A review of environmental contaminations and health in Cambodia Kongkea Phan 1, 2, 3 *, Kyoung-Woong Kim 4 1 Faculty