A/HRC/10/6 page 9 24. In addition, improved access to sanitation would increase school attendance, especially for girls, and help schoolchildren to learn better. It is estimated that lack of access to water and sanitation results in 443 million lost school days each year because of water-related illnesses.22 In addition, girls can be prevented from attending school because of a lack of toilets (or of girls-only toilets).23 25. Addressing issues related to water and sanitation could also have a major effect on the economies of many countries. Treating diarrhoea-related diseases costs an estimated 12 per cent of national health budgets in sub-Saharan Africa.24 There is also compelling evidence that sanitation, as a public health intervention, brings a significant return on investment.25 Unsurprisingly, it is the poorest and most marginalized groups who suffer from the worst sanitation conditions. With widespread disease and illness, worker productivity is drastically reduced. Likewise health risks and epidemics from waterborne diseases can greatly reduce tourism and agricultural exports, with the associated economic costs much greater than the cost of investments in water supply and sanitation to address the problems.26 In total, the potential economic benefits of investing in water and sanitation are estimated at around US$ 38 billion per year.27 26. Despite the benefits of ensuring access to sanitation, it remains the most neglected and most off-track of the Millennium Development Goal (MDG) targets. According to estimates 22 United Nations Development Programme (UNDP), Beyond Scarcity: Power, Poverty and the Global Water Crisis, Human Development Report 2006, p. 45, available at http://hdr.undp.org/en/media/HDR06-complete.pdf. 23 According to UNICEF “Many girls drop out of school at the onset of menstruation, which makes them particularly vulnerable when there are no separate toilets.” See The State of the World’s Children, 1999, Education, p. 52, available at http://www.unicef.org/sowc99/sowc99e.pdf. 24 UN-Water, Factsheet: Sanitation generates economic benefits, available at: http://esa.un.org/iys/docs/2%20fact-sheet_economic%20benefits.pdf. 25 For example according to a study published by WHO, “The cost-benefit ratio of water and sanitation interventions is high when all benefits are included, standing at around between US$ 5 and US$ 11 economic benefit per US$ 1 invested for most developing world sub-regions and for most interventions.” See G. Hutton and L. Haller, Evaluation of the Costs and Benefits of Water and Sanitation Improvements at the Global Level, World Health Organization, Geneva, 2004, available at www.who.int/water_sanitation_health/wsh0404.pdf. 26 WHO, “Looking back: looking ahead - five decades of challenges and achievements in environmental sanitation and health”, 2003. 27 WHO, “Economic and health effects of increasing coverage of low cost water and sanitation interventions”, background document to the Human Development Report 2006, p. 22, available at http://hdr.undp.org/en/reports/global/hdr2006/papers/who.pdf.