Historical Use of Chlorinated Solvents and Their Stabilizing Compounds - Environmental Investigation and Remediation - page 3

equipment design, operator training, monitoring, regulation, and enforcement for continuing solvent
use. Substantial progress is being made toward environmentally safe uses of chlorinated solvents
under controlled conditions. Concurrently, new solvents that pose a somewhat lower threat to drinking
water, the atmosphere, and worker health and safety have been developed and introduced.
The enormous volume of chlorinated solvents used in the United States alone has left a monumental
legacy that will keep contaminant hydrogeologists and environmental engineers occupied for decades.
A compelling aspect of the historical use of chlorinated solvents is that most were ultimately released
to the environment, usually to the atmosphere, but also to soil and groundwater. Solvents that were not
emitted or discharged were incinerated or placed in a landi ll. When solvents were added to products
such as paints, inks, or cleaning agents, the fate of the solvent was often evaporation. Degreasing and
dry-cleaning solvents were discarded when they were no longer usable. In earlier decades, waste sol-
vents were often dumped to the ground or disposed in landi lls, which in the mid-twentieth century
were usually unlined or clay-lined landi lls. Since the enactment of the Resource Conservation and
Recovery Act in 1980, waste solvent has been subjected to “cradle-to-grave” management and hazard-
ous waste manifesting. Waste minimization has emerged as an economical and regulatory compliance-
driven solution to the challenge of safe solvent handling and disposal. Chlorinated solvent consumption
in 2006 was about 10% of the consumption in 1976. The reduction was due to regulatory bans on
ozone-depleting compounds (ODCs), more efi cient degreasing and dry-cleaning machinery, and
replacement of chlorinated solvents by new “designer solvents” and other alternatives.
The history of chlorinated solvent production, use, and regulation has been thoroughly addressed
in Richard E. Doherty's two landmark articles in the Journal of Environmental Forensics (Doherty,
2000a, 2000b). Doherty's articles proi le which solvents were favored for different applications and
how those preferences changed in response to the recognition of worker health and safety issues and
new regulatory restrictions adopted to protect the environment. The sequence of regulations controlling
solvent use, described further in Chapter 6, played a key role in the evolution of which solvents were
put to use for various purposes. Economic and other forces also helped in determining specii c sol-
vent usage. For example, during World War II, chlorinated solvent markets were controlled by the
government: the military received the i rst priority followed by essential uses such as grain fumiga-
tion and refrigeration; dry cleaning received the lowest priority (Doherty, 2000a). Figure 1.1 charts

1200

CTC
TCE
MC
PCE
DCM

1000

800

600

400

200

0
1920

1940 1960

Year

1980 2000

FIGURE 1.1 History of U.S. production of the major chlorinated solvents. (After Doherty, R.E., 2000a.
Journal of Environmental Forensics 1: 69-81. With permission.)