Thirty four million Nigerians – more than the size of any of the nation’s six geopolitical zones – are without toilets, and still practice “open defecation”,  a World Health Organization ’s report has shown.

The practice represents one of the most potentially toxic form of human waste discharge capable of triggering devastating health crisis such as cholera.

According to WHO’s latest update on global progress on drinking water and sanitation released this week, Nigeria is home to one of the world’s 14 largest populations continuing with the practice which is a key indicator of the seventh Millennium Development Goal covering safe water and sanitation.

Nigeria holds the fifth position behind India, Indonesia, Pakistan, and Ethiopia.

In several categories evaluated by the study with last updates in 2010, Nigeria falls amongst the worst performing nations with millions of its population without access to basic sanitation and drinking water.

With 66 million without good drinking water (the worst even in Africa), Nigeria contributes to two-thirds of the world’s population in that category, and 109 million of its population have no access to improved sanitation, the report says.

The 66-page document published on Thursday by the global body appears an indictment of the Nigerian government’s effort at attaining the MDGs – which receives billions of naira annually- as well as the government’s national health policy.

“Ultimately, this report is about optimizing the instruments we have to ensure primary prevention of a major global killer, diarrheal diseases, across all sectors contributing to water and sanitation progress,” said Dr. Maria Neira, WHO Director for Public Health and Environment.

Nigeria has been hit by multiple cholera outbreaks for years resulting in thousands of deaths, and poor sanitation has been blamed for the upsurge in the epidemic.

The scourge claimed 742 lives last year after many states were hit by a wave of water poisoning, health officials had said. This week, the federal ministry of health said the first 12 weeks of 2012, ending March, recorded 175 cases and four deaths.

The MDG drinking water target, which calls for halving the proportion of world’s population without sustainable access to safe drinking water between 1990 and 2015, was met in 2010, five years ahead of schedule.

But the global sanitation achievement has remained dismal, and Nigeria’s performances either way were on lowest rungs, the report shows.

Thirty one per cent of Nigerians had improved sanitation, 25 percent had shared sanitation, 22 per cent had unimproved sanitation while another 22 per cent discharged waste in open locations.

Globally, 60 per cent of the world’s total 1.1 billion who practice open defecation live in India.