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.
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.”
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
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
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.”
more information on eco-san, go to www.ecosanres.org.