urine

Urine testing to diagnose illness or to detect the presence of drugs is generally routine. But a woman who gave her doctor a urine sample months after back surgery got socked with a huge bill. SPL/Science Source hide caption

The chlorine that kills germs in water can interact with sunscreen, sweat and urine to create irritating chemicals. Gregor Schuster/Getty Images hide caption

The average backyard swimming pool could have about two gallons of urine in it. LexyLovesArt/Getty Images/iStockphoto hide caption

Mango trees would be grateful for the nutrients in human poop. Noah Seelam/AFP/Getty Images hide caption