This is a map of the fecal concentration in world oceans. Notice anything? One country, and the ocean which shares its name, appears to be responsible for the vast majority of human feces in the environment. Is this a problem?
Human fecal matter can contain pathogens which spread disease to humans and wildlife alike. In 1998, an estimated 2.2 million deaths were associated with diarrhea, many of them due to fecal pollution of water. This problem is estimated to have gotten worse in the meantime, as population has continued to spiral out of control and little progress has been made to ameliorate problems associated with fecal pollution.
In the 19th century, contaminated water was shown to cause a typhoid outbreak in London, leading the scientific community to accept that sewage was a source of disease. Developed countries began using chlorine filtration to improve the quality of their drinking water, and what followed was a perceptible drop in the prevalence of typhoid. In 1908, there were approximately 30 cases of typhoid per 100,000 people in the US, while in 1990 there were only 400 for the entire population. Typhoid isn’t the only disease associated with human feces in the drinking water. Human poop can contain bacteria like salmonella and e. coli which are linked to a wide variety of major diseases, as well as viruses and protozoa which cause diseases from meningitis to dysentery – potentially deadly without access to adequate care (like in destitutely poor areas of India).
It’s not just the drinking water that we should be concerned about, though. Many foodborne outbreaks are associated with the use of polluted water during production and processing. Shellfish are one food source especially vulnerable to harmful pathogens in the world’s oceans. Fruit and vegetables are impacted by fecally-polluted irrigation water, which is of special concern for foods eaten uncooked. Water-related foodborne outbreaks have resulted in food shortages, which is concerning in a portion of the world as hungry as India where most food is produced locally.
The nutrients and pathogens contained in feces introduces a threat to heath of ocean ecosystems, as well. For example, they can lead to an increased level of blue-green algae, which produces toxins and eventually rots, reducing the amount of oxygen in water, leading to the death of aquatic organisms. Human fecal concentration in the ocean has also been linked to a reduction in costal coral, and pathogens in human feces can easily reach marine mammals, reducing their numbers, also.
Besides the fact that the Indian Ocean is probably gross to swim in, these are the reasons why you should care that it is increasingly becoming laden with poop. Next week, I will cover more about what is being done to combat this oceanic contamination.