Why Food and Environmental securities were left our of the Declaration of Human Rights

After reading about Food and Water security on the United Nation's official website, I believe that it was left out of the basic Human Rights because it is simply to hard to fulfill. UN Secretary General Ban Ki-moon stresses how critical our "finite" water supply is. Later the web page points towards more efficient food production with the use of less water. I believe that with this said, there may be a simple shortage of supply available in those regions of hungry due to the current agricultural practices until we change those practices it is simply impossible to grant Food and Environment as a right.