Organic solvents are widely employed in industry and are used in large quantities across the world. A solvent can be defined as “a liquid that has the ability to dissolve, suspend or extract other materials, without chemical change to the material or solvent”.¹ Organic solvents are so widely used in the modern world as to be ubiquitous and are employed in paints, pharmaceuticals, degreasants, adhesives, printing inks, pesticides, cosmetics, and household cleaners. Commonly used solvents include, isopropanol, toluene, xylene, solvent mixtures such as white spirits and the chlorinated solvents, methylene chloride, trichloroethylene, and perchloroethylene. In Europe alone, approximately 300 000 metric tonnes of chlorinated solvents are sold each year. The United Kingdom’s Health and Safety Executive estimate that 8% of the working population regularly use organic solvents.¹ The largest end user is the coatings industry where solvents play an important role in the quality and durability of paints and varnishes. The volumes of organic solvents used in some industries, for example dry cleaning, are declining, largely due to equipment and process improvements. Increasingly solvents are recovered and recycled, partly in response to environmental controls on volatile organic compound (VOC) discharges.² In addition, environmental legislation has led to a growth in the use of water based paints both in North America and in Europe at the expense of more traditional, solvent based coatings.³ The Montreal Protocol of 1987 was a landmark in environmental regulation⁴ and led to the production of a number of ozone depleting solvents being restricted or phased out. The protocol arose from concerns about the adverse impact of some solvents, including chlorofluorocarbons, on tropospheric ozone. Recently, 1-bromopropane, a solvent introduced to replace ozone depleting agents such as 1,1,1-trichloroethane (methylchloroform), has been shown to be neurotoxic in humans.^5,6

Solvents are volatile agents …