4. Worldwide extent of arsenic problem

Groundwater contamination with arsenic is widespread across the world and should be considered a global issue. It has been reported in at least 36 countries in Asia, the Americas, Europe, Africa and the Pacific.

In the alluvial and deltaic aquifer of Bangladesh and West Bengal, some of those affected are exposed to arsenic concentrations in drinking water more than 300 times higher than the WHO guideline. Mexico, United States, Chile and Argentina are most affected by the arsenic problem in the Americas. It has been estimated that at least four million people are exposed to arsenic levels greater than 50 µg/L in Latin America alone.

In Europe, drinking water for almost 400 towns and villages in the Great Hungarian Plain has arsenic concentrations several times higher the WHO and EC guidelines. A large part of northern Serbia also contains unacceptably high arsenic concentration in drinking water.

The pattern of arsenic presence in different wells can be very irregular with large variations between nearby wells. Arsenic concentrations in a well can strongly increase within a few years of abstraction beginning.

As more countries test for arsenic and drinking water standards become more stringent, arsenic in drinking water will become a problem in an increasing number of countries.