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 ( 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

  • Geochemistry of uranium and thorium in phosphate deposits at the Syrian coastal area (Al-Haffah and Al-Qaradaha) and their environmental impacts 2019-03-16


    The aim of this research was to study the geochemistry of uranium and thorium in phosphate deposits in the upper Cretaceous phosphate deposits in the Syrian coastal area. The study covered three sites, namely Ain Al-Tenah, Ain Laylon, and Al-Mhalbeh. Petrographical study showed that phosphate deposits are of nodular type with micrit to microspaite cement, containing siliceous bone residues, and green grains of glauconite, which are increasing in abundance and volume in the south toward Al-Mhalbeh, reflecting the formation of phosphate in a shallow marine environment. In addition, uranium concentration varied between 3 and 112 ppm in Ain Laylon, 4.2–17 ppm in Ain Al-Tenah and 5–61 ppm in Al-Mhalbeh. Thorium concentration varied between 0.2 and 7.5 ppm in Ain Laylon, 0.3–1.4 ppm in Ain Al-Tenah and 0.3–4.4 ppm in Al-Mhalbeh. The average Th/U ratio in the collected samples was within the range 0.04–0.08 except for five samples which exceeded the value 0.1. Moreover, the 226Ra/238U ratios are lower than unity in all samples, while the 210Pb/238U ratios ranged between 0.4 and 1.2 and the 210Pb/226Ra ratios were found to be higher than unity. On the other hand, the impact of leaching and mobility of uranium and thorium from deposits to the surrounding agriculture fields in the area has been studied using the Radium Equivalent Activity Index (Raeq). The equivalent radium activity was 102 Bq kg−1 in Ain Al-Tenah, 403 Bq kg−1 in Ain Laylon, 407 Bq kg−1 in Al-Mhalbeh and 749 Bq kg−1 in agricultural soil samples. However, the data reported in this study can be considered as a baseline data for the phosphate deposits at the coastal area.

  • Measurement of radon, thoron and their daughters in the air of marble factories and resulting alpha-radiation doses to the lung of workers 2019-03-15


    Concentrations of radon (222Rn) and thoron (220Rn) were measured in the air of different marble factories by using a nuclear track technique. The influence of the marble dust nature and ventilation on radon and thoron concentrations was investigated. It was observed that measured radon and thoron concentration ranged from 310 to 903 Bq m−3 and 6 to 48 Bq m−3, respectively. In addition, alpha-activities due to the unattached and attached fractions of 218Po and 214Po radon short-lived progeny were evaluated in the marble factories studied. Committed equivalent doses due to the attached and unattached fractions of 218Po and 214Po nuclei were evaluated in the lung tissues of marble factory workers. The dependence of the resulting committed equivalent dose on the concentration of the attached and unattached fractions of the 218Po and 214Po radionuclides and mass of the tissue was investigated. The resulting annual committed effective doses to the lung of marble factory workers due to the attached and unattached fractions of the 218Po and 214Po radionuclides were calculated. The obtained results show that about 80% of the global committed effective doses received by workers in the studied marble factories are due to the attached fraction of the 218Po and 214Po radon short-lived daughters from the inhalation of polluted air. Male workers spending 8 h per day (2080 h per year) in a marble factory receive a maximum dose of 34.46 mSv y−1 which is higher than the (3–10 mSv y−1) dose limit interval given by the ICRP. Good agreement was found between data obtained for the average effective dose gotten by using this method and the UNSCEAR and ICRP conversion dose coefficients.

  • Quantitative health risk assessment of inhalation exposure to automobile foundry dust 2019-03-14


    With a growing awareness of environmental protection, the dust pollution caused by automobile foundry work has become a serious and urgent problem. This study aimed to explore contamination levels and health effects of automobile foundry dust. A total of 276 dust samples from six types of work in an automobile foundry factory were collected and analysed using the filter membrane method. Probabilistic risk assessment model was developed for evaluating the health risk of foundry dust on workers. The health risk and its influencing factors among workers were then assessed by applying the Monte Carlo method to identify the most significant parameters. Health damage assessment was conducted to translate health risk into disability-adjusted life year (DALY). The results revealed that the mean concentration of dust on six types of work ranged from 1.67 to 5.40 mg/m3. The highest health risks to be come from melting, cast shakeout and finishing, followed by pouring, sand preparation, moulding and core-making. The probability of the risk exceeding 10−6 was approximately 85%, 90%, 90%, 75%, 70% and 45%, respectively. The sensitivity analysis indicated that average time, exposure duration, inhalation rate and dust concentration (C) made great contribution to dust health risk. Workers exposed to cast shakeout and finishing had the largest DALY of 48.64a. These results can further help managers to fully understand the dust risks on various types of work in the automobile foundry factories and provide scientific basis for the management and decision-making related to health damage assessment.