10/17/2007 - 22:00

The sewer: Guardian against disease

Laura H. Kahn

Laura H. Kahn

A general internist who began her career in health care as a registered nurse, Kahn works on the research staff of Princeton University's ...

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After recently crossing the Atlantic Ocean to spend a year abroad in Paris, I decided to visit the one museum that commemorates a human achievement that trumps Notre Dame, the Louvre, and Eiffel Tower combined in terms of its impact on quality of life--sewage systems. Paris is one of the few cities that celebrates its sewer with a museum. Hidden and generally taken for granted, underground sewers allow large megacities to grow and flourish. As the world population becomes increasingly urbanized--for example, Tokyo/Yokohama has more than 30 million people--sewage removal and treatment will become an increasingly critical factor in preventing epidemics.

Ancient civilizations, most notably Rome, possessed aqueducts and sewage systems that included public latrines. These "public goods" disappeared during the Middle Ages when sewage was dumped into open cesspools of human and animal waste. (See "Tracking Down the Roots of Our Sanitary Sewers.") People drank sewage-contaminated water and waded in streets filled with garbage, dead animals, and excrement. Cholera and plague (diseases of sewage and uncontrolled vermin) were epidemic; city life was deplorable.

Beginning in 1370, Paris began to build underground sewers, but they flowed into the Seine River--the same river that provided the city with its drinking water. It was during the French Enlightenment in the eighteenth century that Western civilization resurrected the concepts of hygiene and sanitation. Alexandre Parent-Duchatelet led the French hygienic movement and devoted most of his medical career to conducting public health investigations, including a review of Parisian sanitation.

After 1800, Paris's population exploded, as people entered the city in search of jobs. When they didn't find any, the city experienced its second bloody revolution in 1830. Two years later, a devastating cholera outbreak occurred in which more than 18,000 people died. These events eventually led to an improved sewer system. (See "Urban Metabolism and River Systems: An Historical Perspective--Paris and the Seine, 1790-1970".)

Paris Sewer Museum

The small kiosk located at the Pont de l'Alma, not far from the Eiffel Tower, belies the enormity of what lies beneath. Posted signs recommend not touching anything and washing one's hands after leaving the exhibits. The stench immediately hit me as I descended down the staircase into the initial hallway named the Hugues Aubriot Gallery after the Parisian merchant provost who introduced the first vaulted sewers at the end of the fourteenth century. During my self-guided tour, which I conducted as rapidly as possible, I passed by antique equipment such as a flushing machine and a flushing boat, which weighed approximately 5 metric tons. Both apparatuses were used to clean the main sewers.

I learned that Napoleon I commissioned Pierre-Emmanuel Bruneseau, the city's municipal works inspector, to survey Paris's sewer network, which took seven years to complete. Bruneseau was a friend of Victor Hugo, who featured the sewers in his classic tome Les Miserables. The museum shows a part of the sewer that Hugo likely used in the book.

The Belgrand Gallery, named after Eugene Belgrand, the engineer responsible for designing the modern sewer and water supply networks built between 1850 and 1894, is the main part of the museum. It has fascinating exhibits on the history of Parisian sewers, but unfortunately, it sits atop a long, metal grate suspended only a few feet above the rushing waters of untreated sewage. Between the noise and the stench, I couldn't stay more than a few minutes. Perhaps that's why the gallery seemed deserted--even though I had seen a large group of schoolchildren enter earlier.

According to the museum, Paris now has 2,100 kilometers of tunnels and has the capability of processing more than 2 million cubic meters of wastewater each day. I took long, deep breaths after I emerged from the depths, but the stench didn't leave my nose until about an hour afterward. I was happy that the odors remained belowground. Aboveground, Paris is a clean city. Garbage is picked up daily, and the streets are washed regularly. (Dog excrement on sidewalks is still a problem; although I've been told that it's getting better.) Sadly, not all governments are willing (or able) to provide such high levels of sanitation.

Cholera: A measure of government failure

When governments are unable to provide clean drinking water and adequate sewage removal, acute diarrheal illness, including cholera, will inevitably surface. The worsening conditions in Iraq over a four-year period exemplifies the nightmare than can develop when public health and sanitation fail. War, terrorism, and human displacement all contribute to these horrific conditions.

From April 28 to June 4, 2003, there were a total of 73 laboratory-confirmed cases of cholera in Iraq; there were no deaths. Around the same time, the four main hospitals of Basra reported 1,549 cases of acute watery diarrhea.

In 2007, almost 7,000 people developed acute watery diarrhea in northern Iraq. Between August 23 and September 6, 2007, 5 out of 11 districts of the Sulaymaniyah Governate had 3,182 cases of acute watery diarrhea with 9 deaths. Of these cases with diarrhea, there were 283 laboratory-confirmed stool specimens of cholera. From July 29 to September 2, 2007, the Kirkuk health authority reported 3,728 cases of acute diarrhea with 1 death. There have now been 6 laboratory-confirmed cases of cholera in that region.

The availability of a clean water supply remains a critical problem in the region. The regional governments are struggling to contain the outbreak by testing and chlorinating the water. Other organizations such as the International Committee of the Red Cross, the World Health Organization, the United Nations Children's Fund, and Medecins Sans Frontieres are also helping local health authorities. The disease appears to be spreading, and there are fears it will reach Baghdad. (See "Cholera Epidemic Infects 7,000 People in Iraq.")

Twenty-first century sewage challenges

According to the United Nations Population Fund, in 2008 more than half of the world's population (3.3 billion people) will live in urban areas. This trend toward urbanization will increase to almost 5 billion people by 2030 with much of the growth taking place in African and Asian megacities. Clean water supplies and effective sewage removal will be critical to the health and success of these urban areas. Government officials responsible for the health of their citizens will need to ensure that the rapid urban growth in their megacities are met with expanded, upgraded, and innovative sewage removal and treatment systems. The tragedies of the nineteenth century shouldn't be repeated in the twenty-first century. Disease outbreaks resulting from sewage and filth simply aren't acceptable.