Asbestos is a naturally occurring silicate mineral with long, thin fibrous crystals. It is known as the miracle mineral because of its soft and pliant properties, as well as its ability to withstand heat. Asbestos is known to be toxic and the inhalation of asbestos can be potentially lethal. Since the mid 1980s, many uses of asbestos have been banned in several countries. The Environmental Protection Agency also banned the use of asbestos and as a result, man-made fibers have been manufactured and used in many applications to replace asbestos. However, asbestos can still be found naturally in the air outdoors and in some drinkable water, including water from natural sources. As this book discusses, studies conducted in laboratory animals have shown that certain man-made fibers may have biological effects similar to those of asbestos. This book addresses this serious health concern caused by asbestos as well as potential fiber-related lung injury due to the inhalation of man-made fiber aerosols.