What is Acetone?
Acetone is a liquid at room temperature. It is colorless, evaporates quickly, and has a mint-like odor. Acetone mixes readily with water and can dissolve many other chemicals. Small quantities of acetone occur in each of us as a natural byproduct of our metabolism. Other sources of acetone in nature include plants, animals, volcanoes, and forest fires. Businesses produce very large quantities of acetone for use in various products and manufacturing processes. 
Structural diagram: National Institutes of Health
Uses of Acetone
Examples of products that may contain acetone, or whose manufacture may involve the use of acetone include: paints, plastics, nail polish removers, paint removers, detergents, liquid waxes, particle board, and some polishes. 
Acetone in the Environment
Because it evaporates so quickly, much of the acetone released to the environment ends up in the air, where it reacts - generally within a few weeks - with sunlight and other chemicals in the air. Acetone released to surface water tends to evaporate quickly. Acetone released to the soil does not usually bind tightly to the soil, but instead may evaporate or move down through the soil into groundwater. Microbes living in the soil or groundwater may use acetone as a food source, and in the process transform it into other chemicals. Acetone does not typically bioaccumulate in plants and animals. 
Health Effects of Acetone
The NIOSH Pocket Guide to Chemical Hazards  lists the following symptoms related to acetone exposure:
Central nervous system depression
When last checked on 25 August 2015, U.S. EPA's Integrated Risk Information System  stated that "data are inadequate for an assessment of the human carcinogenic potential of acetone". As of 7 April 2015, the International Agency for Research on Cancer  had not published an evaluation of the carcinogenic potential of acetone.
 NIOSH Pocket Guide to Chemical Hazards, published by the National Institute for Occupational Safety and Health