Also, organic matter rots and emits methane. Methane is a greenhouse gas that traps heat in the atmosphere at twenty times the rate of carbon dioxide. New York City's Fresh Kills Dump emits over five tons of methane. This is probably why we don't think of it as problematic to the environment. However, human excrement disposal is increasingly becoming problematic.
Many cultures do return their human waste to the soil.
But more and more, excrement is buried, incinerated, or flushed into rivers, bays and oceans. Even human life is threatened by improper disposal of human waste. Some 2 million children die each year. Also, billions of people become sick because of poor water and sanitation facilities. One might continue to believe that sewers and treatment plants are the feasible solution.