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

SEGH Events

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

  • Distribution pattern and health risk assessment of polycyclic aromatic hydrocarbons in the water and sediment of Algoa Bay, South Africa 2018-11-11

    Abstract

    Polycyclic aromatic hydrocarbons are amongst the pollutants of major concern in the terrestrial and aquatic habitats. They are mostly characterised by carcinogenic and non-carcinogenic effects. Distribution and potential health risks of sixteen priority PAHs in the water and sediment samples collected between December 2015 and June 2016 from Algoa Bay, South Africa, were evaluated. Water and sediment samples collected were extracted with liquid–liquid and soxhlet extraction methods, respectively, and then cleaned up using glass column loaded with silica gel. Final concentrations of the target PAHs were determined by gas chromatography interfaced with flame ionization detector. Results indicated that individual PAH concentrations in surface water, bottom water and sediment samples ranged from not detected (ND) to 24.66 µg/L, ND to 22.81 µg/L and ND to 5.23 mg/kg correspondingly. Total PAHs concentrations varied as 12.78–78.94 µg/L, 1.20–90.51 µg/L and 1.17–10.47 mg/kg in the three environmental matrices in that order. The non-carcinogenic risk was generally below 1, whereas risk indices (dermal contact) were above the acceptable limit of 1 × 10−4 in the water column, suggesting possible carcinogenic effects to humans, with adults being the most vulnerable. Similarly, highest contributions to TEQs and MEQs in the sediments were made by benzo(a)pyrene and dibenzo(a,h)anthracene, the two most toxic congeners, signifying the possibility of carcinogenicity and mutagenicity in humans. Diagnostic ratios of PAHs reflect a prevailing pyrogenic input all through. The pollution was albeit moderate, yet regular check is recommended to ensure safe and healthy environment for human and aquatic lives.

  • Potential exposure to metals and health risks of metal intake from Tieguanyin tea production in Anxi, China 2018-11-10

    Abstract

    The metal content of Tieguanyin tea from Anxi, Southeast China, was studied. Leaching experiments were designed based on the local tea-drinking habits, and tea infusions were prepared using three types of water and two methods of soaking tea. Twelve metals (Cd, As, Cr, Pb, Se, Sb, Ag, Tl, Cu, Zn, Be, and Ba) were measured by inductively coupled plasma mass spectrometry (ICP-MS), and a human health risk assessment was performed. The results showed that the quality of water used for steeping tea has a direct effect on the leaching concentrations of metals in the tea infusion and this effect can be reduced by using pure water or commercially available drinking water. Further, the two tea-soaking methods used by local residents can reduce the metal intake. The health risk assessment determined that the carcinogenic risk values of Cr, As, and Pb (Cr > Pb > As) were within an acceptable range (10−7–10−4); therefore, the concentrations of these metals in tea infusions do not pose substantial carcinogenic risk to tea drinkers. The results also indicate that the high concentrations of Tl in the tea infusions pose a substantial noncarcinogenic risk and may result from the dissolution characteristics of Tl and the water quality.

  • Health risk assessment and source apportionment of polycyclic aromatic hydrocarbons associated with PM 10 and road deposited dust in Ahvaz metropolis of Iran 2018-11-09

    Abstract

    The objective of this study was to compare the characteristics of polycyclic aromatic hydrocarbons (PAHs) in PM10 and road dust samples, as well as to identify and quantify the contributions of each source profile using the positive matrix factorization (PMF) receptor model. Health risk assessment was carried out using toxic equivalency factors and incremental lifetime cancer risk (ILCR), which quantitatively estimate the exposure risk for age-specific groups. PM10 samples were collected on PTFE filters in the metropolitan area of Ahvaz. Road dust samples were also collected from all over the urban areas with different land uses. Total PAH concentrations in PM10 and road dust samples were 0.5–25.5 ng/m3 and 49.3–16,645 µg/kg, respectively. Pyrene was the highest PAH in the PM10 profile, whereas fluoranthene became the highest PAH in the road dust. Abundance of benzo[ghi]perylene at PM10 and road dust samples suggested a source indicator for traffic emissions. The results demonstrate that in 36.5% of samples, PM10 concentrations exceed the maximum concentration level recommended by EPA. A multiple linear regression model was used to estimate the influence of meteorological parameters (temperature, wind speed, and relative humidity) on buildup of PAHs. All of PAH species show higher concentrations during the cold and typical days rather than the dust event days and warm periods. PMF analysis showed that vehicular emissions (50.6%) and industrial activities (especially steel industries) (30.4%) were first two sources of PAHs bounded with PM10, followed by diesel emissions (11.6%) and air–soil exchange (7.4%). For road dust samples, three common sources were also identified: vehicular traffic (48%), industrial activities (42.3%), and petrogenic sources (9.7%), in line with that of diagnostic molecular ratios results. According to the results of health risk assessment model, the ILCR of exposure to PAHs associated with PM10 and road-deposited dust was higher than the guidelines of USEPA, indicating high carcinogenic risk.