Southeast Asia has a high rate of arsenic poisoning in the country

Groundwater arsenic contamination is posing a major risk to the health of millions of people, especially in densely populated river deltas of Southeast Asia. Up to now, there is no method to distinguish high-risk areas without having to undertake costly sampling campaigns.

Currently, Eawag has developed a model that allows vulnerable areas to be identified by using available data on geology and soil properties. This enables researchers to identify high-risk areas in areas where groundwater research has not been conducted before, for example in Myanmar and Sumatra.

Worldwide, more than 100 million people are exposed to too much arsenic in drinking water. Arsenic (also called arsenic) is a contaminant made up of natural sources, soluble in groundwater . In many areas, although arsenic contamination has been identified, surface water has been contaminated. Besides, people continue to dig new wells without checking whether water has arsenic.

Take advantage of available data

A Cambodian man showed the effects of arsenic poison on his hands.(Photo: Resource Development International-Cambodia)

In an article published in Nature Geoscience, Eawag researchers have recently described a method that allows relatively high risk areas to be identified without the need for expensive and time-consuming groundwater analyzes. time. For this purpose, the research team led by geologist Lenny Winkel and environmental chemist Michael Berg collected geological data from Bangladesh, Myanmar, Thailand, Cambodia, Vietnam and Sumatra ( Indonesia) to map similar classification.

The material mainly focuses on surface sediments as well as soil properties. Surprisingly, the collection of information can draw relatively accurate conclusions regarding the physical and chemical characteristics of groundwater.

Scientists then investigated the statistical relationship between 30 surface parameters (climate, hydrological and geological data) with arsenic concentrations, eventually combining 8 most relevant variables into a logical regression model. In particular, deposits of young rivers containing many organic components are indications of the situation of arsenic poisoning of groundwater. From the map, it is clear that the probability of high arsenic concentrations is shown in graphical form.

Support from organizations coordinating with the government

Examining the model over 1750 points of groundwater from the Bengal, Mekong, and Red River valleys shows that the predictions are relatively consistent with the actual situation. However, for the model areas that are predicted to be low risk, the risk should be considered to be zero. As Michael Berg points out: 'There is no place without risk' . The environmental chemist also added that basically even for purification models, including more data from deep rock strata, it is not possible to replace water sample analysis. 'But thanks to the map, the government and local officials or support agencies can quickly know where not to dig a well'.

Discover more high-risk areas on Sumatra and Myanmar

The latest discovery of a high-risk region in Southeast Asia is part of the Water Resource Quality (WRQ) project, an Eaway research program focusing on contaminants in groundwater resources worldwide. . Like arsenic, groundwater contains fluoride, selenium and uranium. People are also working on ways to help people overcome contaminated water by using appropriate techniques. Up to now, the project has only been implemented on a very modest scale, but thanks to the support of the project implemented in Southeast Asia, it has been improved relatively well. The new model is particularly suitable for areas where groundwater data are not yet available.

Therefore, the Swiss water research team applied the model to Sumatra, Indonesia, which has an area of ​​100,000 km2 on the east coast, with a high risk of arsenic contamination. The researchers used about 100 groundwater samples to determine the risk that the model predicts to the region at the boundary between high-risk and low-risk areas. Again, the results of the analysis match the prediction: 94% of wells in low-risk areas have arsenic concentrations below 10 µg / L. The map also indicates the risk of increasing arsenic concentrations in groundwater in the Irrawaddy Delta (Myanmar) and the area along the Chao Phraya River in northern Bangkok (Thailand). Both areas have never been found before.

Basic information about Arsenic

Arsenic is one of the dangerous inorganic substances found in drinking water. It is a non-metal and natural ingredient in reefs worldwide with small amounts dissolved in water due to the effects of rain and sun. Inorganic salts of arsenic are odorless and tasteless but have high toxicity to humans. If you eat arsenic on your body for a long time, even at low levels, it is dangerous to your health, including hyperpigmentation, liver and kidney dysfunction along with different types of cancer.

In fact, there are many problems. The first is the varying arsenic concentrations in each locality. Second, people are often not fully aware of the risk because their wells or the groundwater they use have never been tested for arsenic contamination. Arsenic concentrations below 10 µg / L are considered safe. WHO recommends the use of the above arsenic level as a standard for arsenic values ​​in drinking water.

In the Red River and Mekong Delta deltas, Eawag found arsenic concentrations in excess of 100 µg / L in one of the 5 analyzed water samples with a maximum value of 3000 µg / L. The Irrawaddy delta (Myanmar) has arsenic concentrations in excess of 50 µg / L in 2/3 of the well water samples analyzed (according to a study funded by Unicef).

Refer

Lenny Winkel, Michael Berg, Manouchehr Amini, Stephan J. Hug And C. Annette Johnson.Predict groundwater arsenic contamination in Southeast Asia from surface parameters.Nature Geoscience, 2008;DOI: 10.1038 / ngeo254 ((all: Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Du¨ bendorf, Switzerland): 10.1038 / ngeo254 http://dx.doi.org/10.1038/ngeo254