Campaigners are urging governments and businesses to invest more to improve sanitation in poor countries facing a dangerous shortage of toilets.
The toilet crisis is severe in parts of Africa and Asia battling extreme poverty.
To mark World Toilet Day Monday, the group WaterAid said that one in five primary schools and one in eight secondary schools globally do not have any toilets.
According to the report, an estimated 344 million children in sub-Saharan Africa do not have a decent toilet at home, leaving them vulnerable to diarrhoea and other water-borne infections.
Cheryl Hicks, chief executive of the Geneva-based Toilet Board Coalition, told The Associated Press that sanitation entrepreneurs can help reduce the toilet shortage in countries where such infrastructure is too expensive for governments.
(With inputs from agencies.)