Wednesday, January 19, 2011

Arsenic sinks to new depths

Groundwater overuse can push poisonous element deeper — a serious risk for countries in Southern Asia.

Gayathri Vaidyanathan

More than a century of groundwater over-exploitation in Vietnam has drawn the water table down and, with it, arsenic. It may only be a matter of time before the toxic element also permeates deep aquifers in other Asian countries that follow the same practice, such as those around the Bengal Basin.

These conclusions, published today in the Proceedings of the National Academy of Sciences[1], point to high future costs in terms of both health and water-purification processes. Some 100 million people throughout Asia are currently at risk from unsafe levels of arsenic in their water supplies. The element can trigger conditions ranging from anaemia to skin cancer. With deeper aquifers so far thought to be arsenic-free, some municipal authorities in Bangladesh, and many in Vietnam, are drilling into lower sediments.