Swimming in Sewage.

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This month, more than 10,000 athletes competed in the Summer Olympics in Rio de Janeiro. While the Zika epidemic was the chief health concern for athletes, attendees, and many public health experts, another health alarm sounded for the 1,400 participants who competed in the aquatic events. These world-class athletes were swimming in sh*t … literally.  According to a 2015 Associated Press report, they were exposed to water “so contaminated with human feces that they risk[ed] becoming violently ill and unable to compete in the games.” The AP report was based on a well-conducted water sampling study that found alarmingly high levels of disease-causing bacteria and viruses at many event locations, including the famed Copacabana Beach where the competitors entered the water for marathon and triathlon swimming events and thousands of tourists swam. The report also suggested that there was a 99 percent infection risk for athletes who ingested as little as a tablespoon of polluted water. And if that’s not enough, some of the aquatic venues were strewn with floating trash—objects as small as a toy teddy bear, as large as a mattress, and as disgusting as a dead animal.

How did this happen in a city of incredible mountaintop statues, brilliantly costumed Carnival dancers, and tall supermodels? The answer is a poorly functioning sanitation system, the consequence of a troubled economy and rapid population growth. Rio does have a sewage treatment system designed to “clean” its waste before it is discharged into the environment, but about one-third of homes are not connected to the sewer pipes. So a high volume of untreated sewage continually flows through open-air ditches into Rio de Janiero’s rivers and main harbor. And when it rains, the ditches often overflow, resulting in sewage-tinged water that runs down residential streets and contaminates nearby drinking water supplies.

Unfortunately, inadequate sanitation is not limited to Rio de Janeiro. Throughout the world, raw or minimally treated sewage is routinely discharged into rivers, lakes, and oceans. Even Boston’s wastewater management system has a large outfall pipe that discharges effluent into Massachusetts Bay. However, Boston’s sewage discharge is relatively clean thanks to the Massachusetts Water Resources Authority’s Deer Island Treatment Plant, where waste undergoes a multi-step process that includes disinfection, greatly reducing disease-causing microorganisms in the effluent.

The Olympians weren’t so fortunate. Even though Rio’s government was able to implement a few stop-gap measures to remove the obvious trash and lower the most egregious contaminant levels in time for the Olympics, lingering health risks to athletes remain. Measures such as rinsing with antibacterial mouthwash, taking preventive antibiotics, and getting vaccinated for hepatitis A undoubtedly helped, but it’s likely that some athletes will still become ill because of the pollution.

However, the risks to the athletes, while serious, was transient compared to the daily risks of residents. Even though it’s been nearly 170 years since John Snow demonstrated that cholera was spread through fecal contamination of drinking water, the lessons learned from Snow’s elegantly designed epidemiological research and sensible recommendations are still relevant today, since insufficient sanitation accounts for an estimated 1.5 million deaths annually from infectious and parasitic diseases.

So while we still have the attention of the press and the public in the weeks after the Olympics, let’s give voice to the importance of adequate sanitation and clean water for all people, all of the time. As the 2010 United Nations resolution states, “The right to safe and clean drinking water and sanitation [is] a human right that is essential for the full enjoyment of life.” The 2.4 billion people who still live without sanitation will need our help to achieve this right long after the Summer Olympic medals have been awarded.

Acknowledgement: I am grateful to David Ozonoff, professor of environmental health, for his insightful comments on this article.

Ann Aschengrau is a professor of epidemiology at SPH.