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The naturally occurring presence of arsenic in groundwater is an issue that affects millions of rural residents in countries throughout the world, most notably Bangladesh, Cambodia, India, China, Vietnam, Laos, Myanmar, Nepal, Chile, and Argentina. What many of these countries have in common are rivers that flow from major mountain ranges (i.e. Himalayas), and that carry with them large volumes of sediment. Arsenic is carried in these sediments which are eventually deposited in riverbanks and floodplains. These processes have taken place for tens of thousands of years, depositing huge amounts of arsenic contaminated sediments. In regions where the groundwater conditions are just right, the arsenic is released from the sediments and dissolved into groundwater aquifers. In populated areas, these contaminated waters are pumped to the surface by wells and ingested by individuals, families, and communities.

Arsenicosis is a chronic health condition arising from long-term (3 to 10 year) ingestion of arsenic. One of the most common signs of arsenicosis is the hardening and discoloration of skin on the hands and feet, known as keratosis or melanosis. These skin lesions are prone to infection and gangrene and in extreme cases amputation is necessary to relieve suffering. Beyond these external manifestations, arsenic consumption also increases the risk of developing various internal cancers, most commonly lung and skin cancer. In most situations, arsenic cannot be removed by water treatment techniques typical of developing countries, such as boiling or filtering. Most developed countries and the World Health Organization (WHO) have set drinking water quality standards for arsenic at 10 parts per billion (ppb). Many developing countries, including Cambodia, have set their standard at 50 ppb.


Arsenic in Cambodia

The presence of arsenic in Cambodian groundwater was first documented during a small groundwater quality survey conducted by the WHO and the Cambodian government in 2001. Since the initial discovery, several thorough surveys have been undertaken by organizations such as UNICEF, RDI, and Cambodian Ministry of Rural Development (MRD). Six provinces were found to have elevated arsenic risk: Kampong Cham, Kampong Chnang, Kampong Thom, Kandal, Kratie, and Prey Veng. The Royal Government of Cambodia responded to the crisis by forming the Arsenic Inter-Ministerial Subcommittee in 2001 to begin directing government policy on the issue. Additionally, the Ministry of Industry, Mines, and Energy approved Cambodian drinking water quality standards in 2004. MRD and UNICEF also developed an Arsenic testing database and conducted well testing along with RDI. A comprehensive national well database has recently been established and the results of the arsenic testing data are presented in the table below.


Groundwater arsenic contamination is most prevalent in parts of Kandal, Kampong Cham, and Prey Veng provinces. Recently released 2008 National Census data has revealed village level statistics for drinking water sources. Combining this data with village-level arsenic data, it is estimated that between 75,000 and 150,000 people are consuming arsenic contaminated drinking water for at least part of the year in Cambodia, as of 2008.

RDI has a continuing role in the documentation and mitigation of groundwater arsenic problems in Cambodia. Shallow hand-dug wells continue to be a preferable option for arsenic affected areas, and RDI provides an affordable payment program that spreads the cost of the wells over 2 years. The dug wells are fitted with a simple to use and easily-maintained rope-pump system to access the water. Additionally, rainwater tanks and collection systems have been installed at over 50 schools throughout the affected area. RDI is looking to implement new programs such as household rainwater harvesting and community water vendors in high risk communities.

Field teams from RDI and MRD are coordinating house-to-house check-ups in high risk areas to ensure that people are aware about the arsenic problem, to test wells that families are drinking from, and to assess the presence of arsenicosis patients in the area. Surveys are also administered to understand arsenic awareness, drinking water practices, and historical well usage and testing. Where arsenic awareness is low, village meetings are held and informational karaoke and documentary videos are presented to capture the interest of participants and share with them important information about arsenic.


Karaoke Truck

RDI is also working with leading researchers at Stanford, Columbia, and Manchester universities to study the chemical, biological, and physical processes that control arsenic release and spread throughout groundwater systems. These collaborative research projects are also investigating temporal changes in arsenic concentration and the impact of human disruptions to groundwater systems – such as irrigation.


Case Study of Preak Russey Village

Cases of advanced arsenicosis were not discovered in Cambodia until August 2006 when the Ministry of Rural Development’s survey team came across tell-tale signs of arsenic poisoning in Preak Russey village in Kandal province’s Koh Thom district. Experts were brought in to assess the situation, and the diagnosis was confirmed to be arsenic poisoning. Due to the extremely high levels of arsenic found in the tube wells used in the village and the number of people showing visible signs of arsenicosis, RDI worked with UNICEF and MRD and treated the situation with disaster-like urgency. Shallow dug wells were installed and ceramic water filters were supplied for treatment of arsenic-free shallow groundwater, surface, and rain water. In the following months, RDI constructed rainwater harvesting tanks in local schools and did extensive arsenic education using such creative means such as karaoke videos and puppetry. Additionally, funding was received to bring piped water to the community to establish convenient and reliable water sources.

Case Study of Preak Russey Village

Confirming whether well water is safe to drink depends on water quality testing. Several laboratories are operational in Cambodia, one of which is located at RDI. Simple arsenic test kits can be used to measure arsenic concentrations in the field and report results directly to households. However, these test kits report incremental values and rely on a color comparison to determine the concentration. More accurate and precise arsenic testing is often performed using more sophisticated instrumentation. RDI’s laboratory is now equipped with an atomic fluorescence spectrophotometer for professional quality arsenic analysis. From 2000 to early-2010, most arsenic testing in Cambodia was performed using field test kits.


Additional Information and Links

Cambodian Arsenic Center – http://www.arseniccenter.com/
Cambodia Wellmap – www.cambodiawellmap.com
WHO – Arsenic in Drinking Water – http://www.who.int/water_sanitation_health/dwq/arsenic/en/