University of Texas at El Paso student Leirad Carrasco tests a sewage runoff sample taken from Ciudad Juarez, Mexico. The water is used for irrigation in both Mexico and the United States.

Joe Raedle/­Getty Images

Can Wastewater Agriculture Kill You?

­Wastewater farming causes health problems to everyone involved in the process. It's not just the people who eat the food who are exposed to contaminated water. The farmers who use it to irrigate their land are even more at risk than the end consumers.

While bacteria are a serious health threat, the biggest health issue associated with wastewater irrigation is intestinal parasites [source: Ensink]. The World Health Organization (WHO) has determined that one intestinal-worm ovum per liter of water is fine for agricultural applications [source: Ensink]. Researchers found 28 ova per liter on average in minimally treated wastewater (using the pond-settling method, for instance), responsible mostly for roundworm infection. They also were able to identify up to 150 ova per liter in untreated water, leading to a high incidence of roundworm, hookworm and whipworm [source: Ensink]. In severe cases, these parasites can end up killing their host.

Another big problem associated with wastewater irrigation is land and water pollution. Bacteria in the food and water supply can become a permanent, widespread problem when the wastewater poured over cropland contaminates otherwise safe ground water and surface water used for drinking.

Despite these risks, both the International Water Management Institute and the WHO believe the benefits of wastewater farming far outweigh the drawbacks [source: Eichenseher]. Without it, more farmers in developing countries would have no income, and more people would have no food. But these world organizations do have recommendations for making the practice safer than it is right now.

First, it would help if more local farmers adopted indigenous water-treatment methods like pond-settling and composting. Another healthier practice would be limiting wastewater irrigation to use in crops that will ultimately be cooked by the consumer, like rice and other grains. A lot of this depends on education, which is ultimately the way wastewater health issues will have to be addressed, since in most cases, fully treating the water just isn't an option. While most of the farmers who have to use wastewater know it's unhealthy, they may not know about ways to affordably limit the risk. Widespread efforts to educate indigenous populations about simple treatment methods and safer crop choices may help decrease the dangers faced by the 10 percent of the world that relies on wastewater crops for sustenance.

And what about the other 90 percent of the world?

Since so much produce moves around the world, there is always the possibility of being exposed to produce irrigated with wastewater, even if you live in a developed country with high water standards. In the United States, for example, many vegetables are imported from Mexico, and many areas in Mexico don't treat wastewater before it floods into rivers -- rivers that will be used to irrigate crops [source: Bowen].

The best way, then, to avoid the dangers associated with wastewater agriculture is also one of the best ways to cut back on energy costs associated with food production: Eat local. It could end up saving you a lot more than money.

For more information on wastewater agriculture and related topics, take a look at the links on the next page.