SEGH Articles

Arsenic hazard in rice from Kandal Province, Cambodia

08 September 2014
Peter Gilbert won the student prize at SEGH 2014 for best oral presentation.

After a somewhat uneventful 14 hr flight from Manchester, England I had landed in the capital of Cambodia, had my bags ruthlessly checked in front of two armed guards, had drivers practically fighting to give me a lift to my hotel, and travelled on the back of a moped though Phnom Penh’s rush hour traffic, a journey which at the time seemed like the most dangerous ride of my life. The reason we were here; to investigate arsenic concentrations within Cambodian rice, something which at the time of research initiation, had not previously been conducted.

We were to work closely with an NGO called RDIC (Resource Development International Cambodia) who use education and community based projects to implement safe drinking water in areas of high arsenic risk. With their help this study focused on Kandal Province, a region in the south of Cambodia where tube well As concentrations exceeded 3000 µg As/L. Use of contaminated waters for irrigation of rice paddies results in rice with elevated levels of As and given that rice forms 75% of the daily calorific intake in Cambodia it is likely a major source of exposure.

So we set to the task of collecting rice samples for As analysis. Clinging to the back of my translator’s moped and laden with samples of rice we travelled between four large markets in Kandal Province, collecting rice intended for direct human consumption. The origin and variety of rice was recorded totalling 19 different varieties sourcing from 7 provinces as well as Chinese, Vietnamese and Thai imports. After navigating customs with 15 kg of rice, samples were returned to Northumbria University where total As was determined by digestion with nitric acid followed by analysis by Inductively Coupled Mass Spectrometry (ICP-MS). Cambodian grown rice was found to be elevated in As with levels comparable to other As contaminated areas such as India and Bangladesh.

To gain a better understanding of the risk this posed to the local population the second key aspect of this study consisted of a food consumption survey in the village of Preak Russey, with the aim of determining rice and water consumption rates in order to assess absolute and relative contributions to the intake of As. Located four hours south of Phnom Penh and only reachable by ferry crossing Preak Russey is an extremely poor village with agricultural based livelihoods. When As was first identified in Cambodian tube well As concentrations in Preak Russey reached up to 3000 µg As/L with 13% of the population having documented arsenicosis. Two weeks were spent in the village conducting food and water consumption surveys for 20 households through interviews with a translator. Rice was typically eaten three times a day, typically with vegetables or fish with only wealthier households affording a more varied diet containing noodles or meat.

Due to the high consumption of rice and their elevated levels of As it was found that the daily exposure to As through rice would be greater than drinking 2 L of water at the WHO recommended limit of 10 µg As/L. Equally when As ingestion is calculated from both water and rice combined the daily consumption of As breaches the limits beyond which genotoxic effects occur. This study highlights As in rice as a significant environmental hazard in Cambodia and provides a base for further research.

Peter Gilbert (p.gilbert@northumbria.ac.uk) Department of Geography, Northumbria University, England

Keep up to date

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Improving arsenopyrite oxidation rate laws: implications for arsenic mobilization during aquifer storage and recovery (ASR) 2018-04-25

    Abstract

    Aquifer storage and recovery (ASR) and aquifer recharge (AR) provide technical solutions to address water supply deficits and growing future water demands. Unfortunately, the mobilization of naturally present arsenic due to ASR/AR operations has undermined its application on a larger scale. Predicting arsenic mobility in the subsurface during ASR/AR is further complicated by site-specific factors, including the arsenic mobilization mechanisms, groundwater flow conditions, and multi-phase geochemical interactions. In order to ensure safe and sustainable ASR/AR operation, a better understanding of these factors is needed. The current study thus aims to better characterize and model arsenic remobilization at ASR/AR sites by compiling and analyzing available kinetic data on arsenic mobilization from arsenopyrite under different aqueous conditions. More robust and widely applicable rate laws are developed for geochemical conditions relevant to ASR/AR. Sensitivity analysis of these new rate laws gives further insight into the controlling geochemical factors for arsenic mobilization. When improved rate laws are incorporated as the inputs for reactive transport modeling, arsenic mobilization in ASR/AR operations can be predicted with an improved accuracy. The outcomes will be used to guide groundwater monitoring and specify ASR/AR operational parameters, including water pretreatment requirements prior to injection.

  • Heavy metal exposure has adverse effects on the growth and development of preschool children 2018-04-25

    Abstract

    The purpose of this study was to investigate the associations between levels of lead (Pb), cadmium (Cd), chromium (Cr), and manganese (Mn) in the PM2.5 and blood and physical growth, and development parameters including birth length and weight, height, weight, body mass index (BMI), head circumference, and chest circumference in preschool children from Guiyu (e-waste exposure area) and Haojiang (the reference area). A total of 470 preschool children from Guiyu and Haojiang located in southeast coast of China were recruited and required to undergo physical examination and blood tests during the study period. Birth length and weight were obtained by birth records and questionnaire. Pb and Cd in both PM2.5 and blood were significantly higher in Guiyu than Haojiang. Remarkably, the children of Guiyu had significantly lower birth weight and length, BMI, and chest circumference when compare to their peers from the reference area (all p value < 0.05). Spearman correlation analyses showed that blood Pb was negatively correlated with height (r = −0.130, p < 0.001), weight (r = −0.169, p < 0.001), BMI (r = −0.100, p < 0.05), head circumference (r = −0.095, p < 0.05), and chest circumference (r = −0.112, p < 0.05). After adjustment for the potential confounders in further linear regression analyses, blood Pb was negatively associated with height (β = −0.066, p < 0.05), weight (β = −0.119, p < 0.001), head circumference (β = −0.123, p < 0.01), and chest circumference (β = −0.104, p < 0.05), respectively. No significant association between blood Cd, Cr, or Mn was found with any of our developmental outcomes. Taken together, lead exposure limits or delays the growth and development of preschool children.

  • Contamination characteristics of trace metals in dust from different levels of roads of a heavily air-polluted city in north China 2018-04-24

    Abstract

    Concentrations of eight trace metals (TMs) in road dust (RD) (particles < 25 μm) from urban areas of Xinxiang, China, were determined by inductively coupled plasma mass spectrometry. The geometric mean concentrations of Zn, Mn, Pb, As, Cu, Cr, Ni and Cd were 489, 350, 114, 101, 60.0, 39.7, 31.6, and 5.1 mg kg−1, respectively. When compared with TM levels in background soil, the samples generally display elevated TM concentrations, except for Cr and Mn, and for Cd the enrichment value was 69.6. Spatial variations indicated TMs in RD from park path would have similar sources with main roads, collector streets and bypasses. Average daily exposure doses of the studied TMs were about three orders of magnitude higher for hand-to-mouth ingestion than dermal contact, and the exposure doses for children were 9.33 times higher than that for adults. The decreasing trend of calculated hazard indexes (HI) for the eight elements was As > Pb > Cr > Mn > Cd > Zn > Ni > Cu for both children and adults.