Chapter 18 - Chemicals: Solvents

Abstract

The organic solvents are among the most common substances in industry and commerce. They are used for a wide variety of applications where dissolving organic compounds is of interest. Among the principal applications are metal cleaning and degreasing, painting, printing, dry cleaning, adhesives, and fuels and fuel additives. Organic solvents are also common in consumer products such as glues, cleaning products, and inert ingredients in pesticide formulations. When measured by volume, three of the top five hazardous air pollutants released into the air are the common organic solvents toluene, benzene, and xylene. These three substances together comprise approximately 40% of all hazardous air pollutants released into the U.S. air each year. There are some chemicals that are not typically used as chemical solvents, but are usually considered among the solvents due to their similar chemical structure, propensity to release hydrocarbon vapors, and toxic properties. These include styrene monomer, a base substance for production of polystyrenes, and many components of fuels and gasoline. The toxicity of organic solvents is linked in large part to two key aspects of their physical nature, first they are lipophilic and second many are volatile. Lipophilic substances distribute readily across most biological membranes including the common portals of entry (lung, gut, skin) and across biological membranes that may serve as penetration barriers to other substances, including the blood–brain barrier and the placenta.