Perchloroethylene (PERC) is the most common solvent used for dry cleaning in the United States. PERC is a reproductive toxicant, neurotoxicant, potential human carcinogen, and a persistent environmental pollutant. The Environmental Protection Agency is evaluating PERC under the Frank R. Lautenberg Chemical Safety for the 21st Century Act, which amended the Toxic Substances Control Act (amended TSCA), and has mandated that PERC dry cleaning machines be removed from residential buildings. Some local and state programs are also requiring or facilitating transitions to alternative cleaning technologies. However, the potential for these alternatives to harm human health and the environment is not well-understood. This review describes the issues surrounding the use of PERC and alternative solvents for dry cleaning while highlighting the lessons learned from a local government program that transitioned PERC dry cleaners to the safest current alternative: professional wet cleaning. Implications for future public health research and policy are discussed: (1) we must move away from PERC, (2) any transition must account for the economic instability and cultural aspects of the people who work in the industry, (3) legacy contamination must be addressed even after safer alternatives are adopted, and (4) evaluations of PERC alternatives are needed to determine their implications for the long-term health and sustainability of the people who work in the industry.
Introduction
Dry Cleaning and the Use of Perchloroethylene
Dry cleaning uses non-aqueous solvents to clean fabrics (1). The first dry cleaning operations in the United States (US) date back to the 1800s when people washed fabrics in open tubs with solvents such as gasoline, kerosene, benzene, turpentine, and petroleum and then hung to dry. In the 1900s, the US started using specialized machines for the dry cleaning process. However, the use of highly flammable petroleum solvents caused many fires and explosions, highlighting the need to find a safer alternative. The dry cleaning industry first introduced Stoddard solvent (less flammable than gasoline) followed by several nonflammable halogenated solvents, such as carbon tetrachloride, trichloroethylene (TCE), trichlorotrifluoroethane, and perchloroethylene (PERC). Beginning in the 1940s, PERC—also known as tetrachloroethylene or PCE—became the most frequently used dry cleaning solvent (1, 2) and continues to be the primary solvent used to dry clean fabrics both in the US (3) and the European Union (EU) (4).
To comply with environmental regulations, dry cleaning machines have evolved through several “generations” to minimize PERC release. The 1st generation machines were “transfer machines,” where cleaned fabrics were manually transferred from the washer to a dryer. Since then, various pollution prevention controls have been implemented through the subsequent generations, culminating in the latest 5th generation machines, which are closed-loop and equipped with refrigerated condensers, carbon absorbers, inductive fans, and sensor-actuated lockout devices (1, 4–6). As the newer generations of machines were introduced, the amount of PERC used was reduced from 300 to 500 g-PERC/kilogram of fabrics (1st generation) to <10 g-PERC/kilogram cleaned garment (5th generation) (4). In many EU countries, dry cleaning machines older than 15 years are typically prohibited—only 5th generation machines are allowed. However, 4th generation machines may be used if best practices (e.g., good housekeeping, optimal machine operation, and recycling) are implemented and they meet EU emission requirements (4, 7). The US EPA’s National Emission Standards for Hazardous Air Pollutants (NESHAPS) regulations stipulate that 2nd generation machines must be upgraded to 4th generation, and 3rd generation machines must be retrofitted or upgraded to 4th generation machines; only 4th generation and later machines can be sold, leased, or installed (8).
As of 2017 in the US, there are ~20,600 dry cleaning shops and the industry employs nearly 160,000 workers, with ~80% identifying as a racial or ethnic minority (9, 10). The majority of owners are of Korean ancestry (11). Nationwide, 60–65% of dry cleaners use PERC as their primary solvent (1) and most of the remainder use a high-flashpoint hydrocarbon. Other solvents currently used in the US include butylal, siloxane, liquid carbon dioxide, glycol ethers, and water (professional wet cleaning). In Europe, 60–90% of dry cleaning shops use PERC, depending on the country
Specification:Perchloroethylene
| Item | Specification |
| Chroma APHA (Pt-Co) | 15 Max. |
| Density@20℃, g/cm3 | 1.620-1.628 |
| Purity | 99.9% Min. |
| Moisture | 0.005% Max. |
| pH | 7.5-9.0 |
| Alkalinity as NaOH | 0.003% Max. |
| Stability (Copper Corrosion Loss) | 0.50 mg/cm2 |
| Residue after evaporation | 0.005% Max. |
| Residual odor | No odor |
Perchloroethylene
Other Names: PCE
Specification:15 Max.
CAS No.: 127-18-4
Molecular Formula: C2CL4
Molecular Weight: 165.83
Property: Colorless transparent liquid with a smell similar to diethyl ether, insoluble in water, miscible with ether, alcohol, chloroform, benzene, etc.Chemical properties stable, non – flammable, no hydrolysis.
Packing: In 300kg iron drum.