For many people, discussing toilets may not be an appealing conversation over a cup of tea.But for experts from more than 40 countries, that is what they are doing at the World Toilet Summit in the Indian capital, Delhi.The 170 delegates are spending four days examining new ways to provide a basic need to nearly half the world's population.It's an issue that also affects the 700 million Indians without access to toilets, and the hundreds of thousands of Indians who collect their waste.Worldwide, an estimated 2.6 billion people have no access to safe and hygienic toilets, a number the UN hopes to halve by 2015 as part of its Millennium Development Goals."Sanitation is an important and urgent issue," says Bindeshwar Pathak of Sulabh International, an Indian NGO that promotes usage of inexpensive toilets and is joint organiser of this year's seventh annual summit."To achieve the Millennium Goals, it's essential for us to adopt low-cost technology which is easy to use and simple to implement."Open drainsIn India, many localities are dependent on what is known as manual scavenging.Scavengers, who are invariably from the lower-caste, "untouchable" (Dalit) community, clear rubbish and human waste from the streets and open drains outside homes.Mr Pathak remembers being reprimanded by his grandmother for touching a low-caste woman in his village in the state of Uttar Pradesh."She forced me to swallow cow dung, cow urine, sand and Ganges water to purify myself," recalls Mr Pathak.He later lived in a scavenger community for over three months, where he was shocked to come across the case of a newly-married woman forced by her in-laws and husband to clean toilets.For the past three decades, Mr Pathak has worked in the hope that his organisation can liberate scavengers. He has helped develop a range of cheap, squat-type toilets."In India we have half a million scavengers who still manually clean about 10 million toilets daily," says Mr Pathak."If they have done good things for the society by cleaning toilets, what has the society done for them?"Society has kept them at the lowest level of the social hierarchy - the untouchables, the lowest among the low."'Untouchables'Most of these scavengers are Dalits - the lowest rung of Hindu society who continue to face discrimination and prejudice.And an overwhelming 80% of them are women."I've grown old doing this dirty work," says Sharadah, a manual scavenger in Nand Nagri, a village on the outskirts of Delhi."For the past 20 years I've been cleaning toilets because this is the only way I can feed my children. Everyone considers us dirty and stays away from us. If I was able to find another job, why would I do this?"With a broken cycle-rickshaw, Sharadah and her husband head out every morning to clear away waste.Visiting about 40 houses and working for more than 12 hours a day, they earn just $15 a month - barely enough to support their seven children."When I first went to do this job I was 21 years old. I was so overwhelmed by the stench and smell that I felt sick and fainted, falling in the gutter," says Sharadah."No one came to pick me up because I was covered with filth. I sat there crying until one of my family members came. I felt so disgusted that I could not eat the whole day!"Sharadah's daughter, Meena, started working as a scavenger after failing to find other work. "My husband was unemployed and often drank alcohol or took drugs. We had no income and I had to find a way out," she says."Initially, I tried looking for a job in a school or nursing home, but no one would take me. The first question they always ask is your caste-system."EradicationMeena is currently working as a volunteer with Safai Karamchari Andolan (SKA), a nationwide movement aimed at eradicating manual scavenging in India by 2010."Manual scavenging is most prevalent in the Indian states of Uttar Pradesh, Rajasthan, Madhya Pradesh and Gujarat," says Bezwada Wilson, the national convener of SKA."This is an issue of dignity. But working in such nasty conditions, scavengers are also suffering from health problems," he says.According to Mr Wilson, the stench forces scavengers to hold their breath for long periods of time, causing respiratory problems.The Indian government banned manual scavenging in 1993, but the law is not widely implemented."There has not been a single prosecution for violating this law in India, so who will obey or implement this act? Most districts are not even aware [of the law]," Mr Wilson says."Because of the practice of the caste system in India, people have been forced to do such menial jobs. Focus should now be given on how to liberate scavengers from this.""We already have flush toilets - what is needed is rehabilitation."