About 2.4 billion people — or roughly one-third of the world’s population — still lack access to proper toilets, according to a report published Tuesday by the World Health Organization and UNICEF.

The study warns that progress on sanitation is falling short of the targets outlined in the U.N.’s Millennium Development Goals, even though significant improvements have been made in related areas including access to safe drinking water. Today, only 68% of the world’s population has access to proper sanitation facilities, a handful of percentage points short of the goal of 77%. Many of those who lack proper toilets and defecate in the open live in South Asia and sub-Saharan Africa, according to the report.

“Until everyone has access to adequate sanitation facilities, the quality of water supplies will be undermined and too many people will continue to die from waterborne and water-related diseases,” said WHO public-health director Dr. Maria Neira in a statement.

The U.N. is expected to outline new Sustainable Development Goals in September, with a goal of expanding sanitation facilities and eliminating open defecation by 2030.

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