Here’s What You’ll Find in 3 Teaspoons of Rio’s Water

By Nathaniel Scharping | August 3, 2016 3:48 pm

Trash in the waters of Guanabara Bay in Rio de Janeiro, Brazil. (Credit: Donatas Dabravolskas/Shutterstock)

A single gulp of ocean water, or roughly three teaspoons, is all it will take for athletes and tourists to contract potentially deadly diseases at the 2016 Rio Olympics.

That’s the consensus of a recent study commissioned by the Associated Press looking at levels of viruses, bacteria and other microbes in the water of Rio de Janeiro’s Guanabara Bay — home of historic Copacabana and Ipanema beaches.

The study, carried out by an unnamed researcher at Brazil’s Feevale University, reported initial results last year, and found viral loads up to 1.7 million times higher than what are considered safe concentrations in most countries. An AP article published this week reiterates those findings, and a biology professor at the University of South Florida offered some free advice: “Don’t put your head under the water.”

But what, exactly, is swimming in a mouthful of water from the bay?

Lots of Company

While the AP has not released the actual data from their study, the findings appear to agree with a different study also published last year from researchers in Brazil. That study focused on levels of bacteria and algae found in Guanabara Bay, home of the sailing events. Those researchers concluded: “The majority of the beaches within the bay are not appropriate for swimming.”

Here’s a taste of what’s in the water (at various concentration levels):

  • Coliforms: bacteria that are not necessarily harmful themselves, but which indicate that other, more deadly bacteria are likely present.
  • Clostridum: the microbe behind botulism, tetanus and colitis
  • Heightened levels of Gammaproteobacteria: a class of bacteria that includes species of Vibrio, known to cause intestinal infections.
  • Klebsiella: can cause pneumonia and urinary tract infections.
  • Pseudomonas: also a cause of pneumonia, and could also trigger blood infections.
  • Antibiotic-resistant superbugs: This includes Vibrio cholerae, which causes cholera, Klebsiella pneumonia, and Shigella bacteria, which leads to an intestinal infection. A few of these bacteria were even shown to be multi-resistant, meaning that they exhibit an immunity to more than one kind of antibiotic.
  • Bacillus: the menace behind food poisoning.
  • Adenoviruses: a broad class of viruses that causes common afflictions such as colds and diarrhea, but also more menacing diseases like pneumonia and bronchitis.
  • Rotaviruses: most often causes gastroenteritis, an inflammation of the intestinal tract that leads to stomach pain, vomiting and diarrhea.

Many of the bacteria were present at extraordinarily high levels, meaning the risk of infection is frighteningly large.


Relative abundance of phylogenetic groups to metagenomes (at class level) in three sites of Guanabara Bay. (modified from Gregoracci et al., 2012)

Along with the untreated waste, algae blooms are becoming more common, fed with an ample supply of phosphorus and nitrogen from the sewage and runoff. These blooms are known to produce harmful toxins, and suck up oxygen in the water, killing off the fish many residents depend on for their livelihoods. The unnaturally nutrient-rich conditions also favor particular types of bacteria over others, some of which can be harmful to humans.

The AP found that 90 percent of sites sampled had worrying levels of adenoviruses, which lead to a host of infections, and Ipanema beach, and likely others, saw levels of rotavirus exceeding 32 million per liter. You don’t even have to go in the water to be at risk — tests of the sand itself also found greater than average levels of viruses. Some species of bacteria break down in warm water and sunlight, both of which are ready commodities in Brazil. Viruses, on the other hand, don’t disappear so easily.


Vibro cholerae (Credit: Wikimedia Commons)

It’s a Sewer

Rio de Janeiro has for years been pumping large quantities of raw sewage into the bay, in addition to industrial waste from 16,000 sources and freshwater runoff, which also contains contaminants. It is estimated that as much as 18 cubic meters of raw sewage flows into the bay per second. However, plans to upgrade the water treatment system have repeatedly been put on hold.

The Rio Olympics were meant to provide the impetus for the city to clean up its act, but the time for that has come and gone. In just a few days, Olympic athletes will be sailing, rowing and swimming in waters that are constantly subject to an influx of raw sewage, and which consistently contain far above safe levels of potentially harmful microbes and viruses.

MORE ABOUT: pollution, water
  • crunchycon1

    You’d have to be insane to be anywhere near the water in Rio.

    • disqus_f23yWYhDc9

      But brazilians are hot!!

      • crunchycon1

        The “hotness” has nothing to do with the water. I don’t think the viruses are passed on by sexual transmission. I can guess what the STD rate is though.

    • Lorie Franceschi

      But, But the water in Rio is connected to all the water in the World AHAHAHAHAHAHAHAHAH!

      • crunchycon1

        I assume this is humor. You couldn’t get me near the water, no matter how hot the Brazilians are. I’d have to be about 10 miles off shore before I’d go near it.

        • Nicholas

          You’d be doing them a favor because I’m sure Brasil doesn’t want you even close to Rio or its beaches.

          • crunchycon1

            So I assume you would have no problem going in the water

          • Nicholas

            After reading the article I would attempt to keep my mouth above water but there are bacteria and virus everywhere in the world and few get sick, its better to focus on the beauty of the place rather than exaggerate things you can’t even see as in this case. I was in Rio not long ago and in my opinion its one of the coolest beach cities in the world, unfortunately contamination is part of almost every major costal metropolis

          • crunchycon1

            Nicholas, you’re a braver man than I am. Given the scientific analysis of the water, for me, it wouldn’t be worth the risk. I have no doubt that Rio is a beautiful place.

  • Uncle Al

    Silver and bronze medal winners also receive the metal medal ($675, $385, $5) plus emoluments ($25K , $15K , $10K) for gold, silver, bronze respectively. A gold medalist would be blessed with taxable $25,675 income. The IRS then confiscates $8986, and further subtract state tax.

    A whole bunch of athletes will sicken and perhaps die, bring home Zika and fetal microcephaly, then be jailed for tax evasion. My vicious idiot government rations life, liberty, and the pursuit of happiness.

  • John C

    Why did they pick Rio in the first place?

    • Mississauga_Dad

      It’s called ‘Polympitics’.

    • Ivar Ivarson

      Like Islamic terrorism, the motives of the IOC members will never be known.

    • GORT

      What makes the selection of Rio for the SUMMER Olympics so odd is that, oops, Brazil is technically in the middle of its WINTER. So much for technicalities, eh?


  • Mississauga_Dad

    A new team medal competition has been initiated for Rio 2016: The top three teams with the fewest fatal diseases contracted while competing.

  • hummingbird

    What would it take to clean the water? A few billionaires could easily get together and pay for the science and permanent cleaning of the water system. Instead they do nothing except enrich themselves further.

    • disqus_f23yWYhDc9

      They need to add chlorine to their beach water. My swimming pool has chorline, and it keeps the germs at bay!

  • crunchycon1

    It’s a damn shame, because their mayor talks a good game about cleaning up the water, but has come up small. There are plenty of statements and platitudes, but very little. action.

  • John Strickland

    Brasil is a dirty country…not surprised at all.



Briefing you on the must-know news and trending topics in science and technology today.

See More


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Collapse bottom bar