Polyps are a common finding during recommended screening exams of the colon and rectum, occurring in approximately 20 to 30% of American adults. Polyps are abnormal growths arising from the inner lining of the colon or rectum. Some polyps are flat; others have a stalk. Polyps can occur throughout the large intestine, but are more commonly found in the left colon, sigmoid colon and rectum. The large majority of polyps will not become cancers; however, certain types of polyps are precursors to cancer development.
DEFINITION of 'Nonrenewable Resource'. A resource of economic value that cannot be readily replaced by natural means on a level equal to its consumption. Most fossil fuels, such as oil, natural gas and coal are considered nonrenewable resources in that their use is not sustainable because their formation takes billions of years.
Fossil fuel (such as oil, petroleum, natural gas and coal) and radioactive fuel (uranium) are the most common non-renewable energy sources. These resources are indeed renewable, but the fact that it takes thousands of years to grow or generate them, makes them non-sustainable and therefore non-renewable.