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n Christine Moe’s first trip to El Salvador, she was six months pregnant with her second son and on a mission. She traveled extensively throughout the rural countryside, photographing latrines in preparation for a research study on sanitation. In a neighborhood at the center of San Salvador, she found houses tightly packed together with rudimentary toilets either attached to the house or sometimes located inside. In other parts of the country, she observed a range of sanitary conditions from toilets housed in solid constructions with brick walls, metal roofs, and doors to others patched together using plastic bags and palm leaves, partially roofed and lacking a door.
       These eight years later, the health educator who carefully guided her across the rutted roads on that first trip is now working on the research project that Moe helped establish at the Ministry of Health in El Salvador. And Moe herself is still actively involved in sanitation research there. As associate professor of International Health at the Rollins School of Public Health (RSPH) and co-director of the Center for Global Safe Water, she continues her mission—in her own words, “to build a better latrine.”
       Although sanitation is a vital ingredient in the success and sustainability of safe water initiatives, it is “the poor stepchild in the picture of water,” Moe says. Providing safe water is an easier sell to donors and foundations whereas sanitation funding is harder to come by, according to Moe. “People will donate money to dig a well,” she says. “They can have their name engraved on a plaque on the well and have their photograph made with the local politician standing by the well. But no one wants to have his name on a latrine. Sanitation is the ignored part of the equation.”
     It’s too big a part to ignore in Moe’s opinion. Almost half of humanity, some 2.4 billion people, lack safe sanitation today. Of those, between 2 million and 3 million people die each year as a result of inadequate sanitation, insufficient hygiene, and contaminated food and water. Some 6,000 children die every day of diseases associated with lack of access to safe drinking water, inadequate sanitation, and poor hygiene—the equivalent to 20 jumbo jets crashing every day.

n the developed world, sanitation practices rely on a flush-and-discharge technology, using water to transport and dispose of human waste. Yet in many parts of the world, where water is a scarce resource or sewage treatment is unaffordable, that approach doesn’t make sense. Instead, people in developing countries often use a drop-and-store method of waste disposal. While this can work in the countryside, in urban and peri-urban areas, people lack space to dig new latrines when old ones fill up and may face difficult soil and groundwater conditions. As a result, their shallow pits can contaminate groundwater and surface water.
     An alternative solution of which Moe is an advocate is called “ecological sanitation,” or “eco-san” for short. Pioneered in Scandinavia and China, instead of viewing human excreta as waste, the eco-san approach sees human waste as a resource. Nutrients contained in excreta are sanitized, then recycled for use in agriculture. Recycling sanitized urine and feces restores a natural cycle, preventing water pollution and returning nutrients to the soil to promote better agriculture.
     The approach mimics nature itself. In nature, there is little waste. The products of one living thing are the raw materials for others.
     “The eco-san approach used to be considered by some as on the lunatic fringe,” says Moe, “but now people realize that it embodies simple, sustainable, and fundamental concepts.”

n the sanitation field, Moe finds many nongovernmental organizations want to do an intervention but rarely are there evaluations to see if the interventions work. “We emphasize doing and not evaluating,” says Moe. “Yet if an intervention is not working safely, it is not helping the cause of public health and is a waste of limited resources.”
     A longitudinal study in El Salvador run by Moe is evaluating one sanitation program. In the 1990s, the El Salvador Ministry of Health (with funding from UNICEF) installed thousands of double-vault, urine-diverting (DVUD) toilets and fewer numbers of solar toilets throughout the country. The toilets use an eco-san approach in storing fecal waste under conditions that promote the destruction of pathogens. The treated solids are used as soil conditioner in agriculture.
     At the request of UNICEF, with support from the Thrasher Research Fund and the Pan American Health Organization, Moe assembled an international team—headed by Ricardo Izurieta—to evaluate this approach. They began with a baseline survey of 396 households with DVUD and solar toilets in one urban and six rural communities in El Salvador. The majority of toilets had been in operation for an average of more than six years.
     The investigators collected information on household demographics, water supply and treatment, toilet use and maintenance behaviors, problems with toilet use, and household knowledge and attitudes about toilets and disease transmission. They also conducted a sanitary inspection of the toilet, and they opened the vault not currently in use and collected samples from the top, center, and bottom.
     To facilitate the microbial analysis of the samples, Moe set up a local laboratory that now serves as a reference environmental microbiology laboratory for Central America. Her team determined the presence of specific indicators (such as fecal coliforms) as well as Ascaris eggs to see how well microbial pathogens had survived. They measured pH in the samples as well as moisture content. Lana Cohen Corrales, 03MPH, a graduate student at the time of the project, studied specific infections in families using the latrines, finding clear differences in enteric infections in families and villages, depending in part on the type of sanitation facilities they had.
     In the first analysis, as well as in an additional follow-up study, the researchers pinpointed the most important factors for pathogen die-offs: latrine temperature and pH. One solar design—supplemented with the addition of ash—worked best of all, reaching the highest temperature and pH levels. Their ideal latrine was a solar model with a shallow but adequate vault size to allow longer storage and good solar orientation to promote higher temperatures. In another important finding, they discovered that biosolids from some eco-san systems were still hazardous even after months of storage. They recommended reusing these biosolids with caution and only after longer storage times.
     Another student, Tierney Murphy, 03MPH, completed an analysis of the sanitation behaviors of the people using the latrines. She examined how the behaviors and household factors, such as number of people using the latrine and maternal education, influenced pH and temperature. Based on her analysis, the researchers emphasized the importance of health education, including simple health messages on how to safely use and maintain eco-san latrines. These initial instructions, they recommended, needed frequent follow-up and reinforcement.
     In fall 2003, Murphy and Corrales joined Moe and others to present their findings to the Vice-Minister of Health in El Salvador and the UNICEF representative. They also have presented their data at four international conferences—in Sweden, China, Germany, and El Salvador. Moe is now part of a panel of experts drafting WHO guidelines for safe use of biosolids from latrines.
     By getting the findings to the appropriate policymakers, Moe hopes to generate an interest in funding of further sanitation research. She sees a need for studies in different climates with different use and maintenance conditions as well as more studies on the health impacts of different eco-san systems. She is still searching for ways to improve eco-san design, or as she says, “My mission is to make the best latrine possible.”

For more information on eco-san, go to


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