Despite improved sanitation worldwide last year, there are still about 2.6 billion people - or about 41 percent of the world population - lacking adequate toilet facilities.

The United Nations says the annual cost of meeting the water and sanitation targets in the Millennium Development Goals by 2015 is about $11.3 billion, of which $9.5 billion is for sanitation alone. The world body is currently assessing the successes and failures of the International Year of Sanitation 2008. Meanwhile, the Seoul-based World Toilet Association (WTA) - working in some of the world's poorest nations, including Cambodia, Cameroon, Ghana, Kenya, Laos and Mongolia - is calling for "a new toilet culture and a toilet revolution".

The MDGs call for a 50-percent reduction in the number of people living without adequate sanitation or toilets.