(ORDO NEWS) — Between 94 and 220 million people, 85–90 percent of whom live in South Asia, are at risk of getting arsenic into their bodies due to their water supply: they use deep-seated groundwater to produce drinking water and irrigate crops.
Scientists compiled a world map of the distribution of arsenic in groundwater and assessed the risks of its consumption by people, the results of the study are published in the journal Science.
Arsenic is an extremely toxic chemical element, the ingress of which into the human body can lead to diseases of the skin, cardiovascular and nervous systems, as well as contribute to the development of cancer.
The World Health Organization has established the recommended concentration of arsenic in drinking water at a level of no more than 10 milligrams per liter. The main threat is the use of groundwater: arsenic accumulates in aquifers, where reducing conditions contribute to its release from iron-containing minerals.
In many arid regions of the world, the subterranean stratum is the main source of fresh water for drinking and watering crops, and the local population is at risk of arsenic poisoning through rice and drinking water.
A global assessment of the risk of arsenic poisoning from groundwater has not yet been carried out due to difficulties in obtaining data on water use and agriculture by developing countries, as well as insufficient environmental monitoring of the chemical composition of groundwater in such regions.
Scientists led by Joel Podgorski and Michael Berg of the Swiss Federal Institute for Water Sciences and Technology have created the first world map of the distribution of arsenic in groundwater (with a depth below 100 meters from the surface).
To develop it, they summarized data from nearly 80 studies of arsenic in aquifers, which included 200 thousand water analyzes and about 55 thousand sampling points in the territories of Burkina Faso, Argentina, Mexico, China, South and Southeast Asia, the USA and Delta The Red River in Vietnam, as well as sedimentary basins around the world.
To determine previously unknown areas of arsenic pollution, the authors of the study carried out mathematical modeling using 52 predictor variables: soil properties (particle size distribution, organic matter, pH), geological and climatic (precipitation, actual and potential total evaporation, and air temperature) indicators as well as a topographic moisture index.
However, the pollution of deep-seated groundwater with arsenic does not yet mean increased risks to human health – because they may not use this water on the farm.
Therefore, the authors of the study conducted an assessment of the risks of poisoning people with arsenic, using the information presented in the UN AQUASTAT database on food and agriculture.
The final arsenic risk assessment indicated that between 94 and 220 million people worldwide (of which 85 to 90 percent live in South Asia) are at risk of arsenic entering the body due to the organization of water supply.
Scientists also noted that with the intensification of agriculture in developing countries and the use of groundwater for irrigation, the number of such people will continue to grow.
A major step towards food security could be the modernization of irrigation systems: a recent study showed that it can feed an additional 800 million people
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