Maps, compasses, astrolabes, and calipers are among the early tools used by ocean navigators. In the modern era, these tools have been largely replaced by electronic and technological equivalents. Despite these early beginnings, it would take many centuries before global navigation at sea became possible.
Radon for Children. Harmful Effects of Radon. Radon is the second leading cause of lung cancer (diagram to the right) and a serious public health concern. The primary adverse health effect associated with chronic exposure to radon is lung cancer (typically bronchogenic): -squamous cell carcinoma. -small cell carcinoma.
It exists in both natural and man-made forms and has many beneficial uses, including x-rays and the generation of electrical power. Radon is a natural form of radiation that can cause serious health problems and is often found in igneous rock and soil. An odorless, colorless radioactive gas, radon is estimated to be the second leading cause of lung cancer in the United States, responsible for over 20,000 estimated lung cancer deaths each year.