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We work with King County dry cleaners to help them use less toxic chemicals. Dry cleaners use many chemicals that can harm the people who use them as well as the environment.

  • Spot cleaning products can contain powerful acids and hazardous organic solvents.
  • The most commonly used dry cleaning solvent is perchloroethylene (or "PERC").
  • PERC is believed to cause cancer and can harm the nervous system, the liver, and the kidneys.

Understanding the industry

In 2010, we sent a questionnaire to every dry cleaner in King County. Here are highlights of the survey. Of the people who filled out the questionnaire:

  • 84% were Korean.
  • 81% wanted technical information in Korean.
  • 69% used the chemical perchloroethylene (PERC) and 21% used an alternative hydrocarbon solvent.
  • 75% did not know that PERC is harmful to their health.
  • 76% of those who used PERC machines said costs prevent them from replacing their PERC machines.
  • 61% did not adequately protect their lungs when cleaning out still bottoms.
  • Of PERC machine users, less than 40% used a leak detector. Environmental Protection Agency regulations require the use of a leak detector.
  • 98% disposed of their still bottoms as hazardous waste. This suggests that most comply with hazardous waste regulations.
  • 69% shared a building with a business that sells or serves food. This is a concern because fatty foods absorb PERC.

For more information see A Profile of the Dry Cleaning Industry in King County, Washington (PDF) or contact Steve Whittaker at 206-263-8499 or steve.whittaker@kingcounty.gov.

Evaluating the alternatives to PERC machine

Alternative solvents: Understanding the processes
From the survey we learned that over 20% of dry cleaners are using one of the new solvent alternatives to PERC.  Most shops were using a hydrocarbon solvent, like ExxonMobil’s DF2000, although some shops use a new process, called System K4.

We wanted to learn more about the chemicals used in these new dry cleaning processes and the wastes they generate. This is what we found from a sampling study:

For more information see Characterizing Alternative Solvent Dry Cleaning Processes (PDF) or contact Steve Whittaker at 206-263-8499 or steve.whittaker@kingcounty.gov.

Toxicity of Solvon K4 dry cleaning solvent in fish

We tested the toxicity of Solvon K4 product in juvenile rainbow trout. The LC50 (or lethal concentration that killed half the test fish) was 45.7 milligrams per liter (mg/L).

Based on this LC50 result, when someone wants to discard unused or off-specification Solvon K4 product in Washington state, it must be disposed of as Dangerous Waste (DW) with the waste code “WT02”.

For more information see Evaluation of Solvon K4 in an Acute Fish Toxicity Test (PDF) or contact Steve Whittaker at 206-263-8499 or steve.whittaker@kingcounty.gov.

Toxicity of DF2000 dry cleaning solvent in fish

We tested the toxicity of unused DF2000 towards juvenile rainbow trout and found that this dry cleaning solvent failed to kill fish at the highest tested concentration of 5000 milligrams per liter (mg/L). Therefore, unused or off-specification DF2000 solvent that requires disposal would not designate as dangerous waste in Washington state. We also learned that DF2000 is comprised primarily of long chain hydrocarbons between C-10 and C-12, and does not contain hazardous chemicals like benzene or toluene.

For more information see Evaluation of DF2000 Dry Cleaning Solvent in an Acute Fish Toxicity Test (PDF) or contact Steve Whittaker at 206-263-8499 or steve.whittaker@kingcounty.gov.

Toxicity of still bottom wastes from alternative solvent dry cleaning

The still bottom wastes from hydrocarbon and System K4 operations are more toxic to fish than the solvents used in these dry cleaning processes.

We learned that the still bottoms contain residual dry cleaning solvent and detergent. We found that the detergents are very toxic to fish. Therefore, the detergents are likely responsible for the toxicity of the still bottoms.

These detergents are so toxic to fish that if someone wants to discard unused or off-specification detergent product in Washington state, it must be disposed of as Extremely Hazardous Waste (EHW) with the waste code "WT01".

We recommend that

  • detergent manufacturers replace surfactants with ingredients that are less toxic to fish and other aquatic organisms,
  • dry cleaning machine manufacturers identify the smallest amount of detergent needed to clean effectively, and
  • dry cleaners ensure they add detergent according to the manufacturers' recommendations.

For more information see Evaluation of Still Bottom Wastes from "Alternative Solvent" Dry Cleaning (PDF 5MB) or contact Steve Whittaker at 206-263-8499 or steve.whittaker@kingcounty.gov.

Evaluating worker exposures to alternative dry cleaning solvents

We collaborated with investigators from the National Institute for Occupational Safety and Health (NIOSH) to learn about exposures to newer alternative solvents to perchloroethylene when workers are dry cleaning.

These studies were conducted at local dry cleaning businesses that used either hydrocarbon solvent (DF2000) or Solvon K4 (also known as butylal).

We learned that the highest concentrations of solvents in air were measured when employees loaded and unloaded the dry cleaning machines and while pressing clothes.

Low concentrations of formaldehyde were also detected in the Solvon K4 shop, but NIOSH stated that they could not be sure that it originated from the dry cleaning machine.

NIOSH also provided some recommendations for the shop owner and employees to help reduce their exposures to the dry cleaning solvents and other chemicals.

For more information, see Evaluation of occupational exposures at drycleaning shops that use SolvonK4 and DF-2000 and the article in the NIOSH Science Blog. You may also contact Steve Whittaker at 206-263-8499 or steve.whittaker@kingcounty.gov.

Understanding high-flashpoint hydrocarbon dry cleaning solvents

We evaluated three high-flashpoint hydrocarbon dry cleaning solvents (DF2000, EcoSolv and Calypsolv) by performing chemical analyses and fish bioassays. We also performed an extensive literature review on the chemistry and toxicology of these products and interviewed several industry product specialists.

We learned that these products are complex mixtures of hydrocarbons, but we did not detect hazardous aromatic compounds, like benzene. None of these products were acutely lethal toxic to fish at the highest tested concentration (100 mg/L), likely because they are not very soluble in water.

From our literature review and interviews, we learned that understanding the toxicity of these products complicated by: 1) the inclusion of diverse products in the category of "hydrocarbon dry cleaning solvents," some of which may contain benzene and other hazardous substances, and 2) the inadequacy of Chemical Abstract Service (CAS) numbers to uniquely identify specific products within this chemical class.

For more information, see Dry Cleaning with High-flashpoint Hydrocarbon Solvents (PDF 2 MB) or contact Steve Whittaker at 206-263-8499 or steve.whittaker@kingcounty.gov. The technical appendices to this report are presented in a separate document (PDF 11 MB).

 


DetectorsPERC dry cleaning

Evaluating PERC vapor leak detectors

Most PERC dry cleaners do not own or use a vapor leak detector, even though federal and state regulations require that they test their equipment for leaks. We tested several leak detectors and identified three that would be most suitable for use by dry cleaners (TIF models RX-1A, XP-1A, and ZX) and a fourth detector that did not have so many features but worked well and was less expensive (Infinicon TEK-Mate).

For more information see Evaluating Vapor Leak Detectors for use in "PERC" Dry Cleaners (PDF) or contact Steve Whittaker at 206-263-8499 or steve.whittaker@kingcounty.gov.


Toxicity of perchloroethylene still bottoms in fish

We tested the toxicity of still bottom wastes from four perchloroethylene dry cleaning machines towards juvenile rainbow trout. According to Washington state's dangerous waste regulations, one sample was Extremely Hazardous Waste (EHW) with waste code "WT01"; the other three samples were Dangerous Waste (DW) with waste code "WT02". Therefore, the toxicity of these wastes varies from shop-to-shop, likely because of variation in the amount of perchloroethylene, detergent, and other substances that are toxic to fish.

For more information see Aquatic Toxicity of PERC Still Bottom Wastes: A Pilot Study or contact Steve Whittaker at 206-263-8499 or steve.whittaker@kingcounty.gov. The technical appendices to this report are presented in a separate document.

Toxicity of PERC dry cleaning solvent in fish

We tested the toxicity of unused PERC solvent product in juvenile rainbow trout. The LC50 (or lethal concentration that killed half the test fish) was 3.61 milligrams per liter (mg/L). This finding confirms that PERC is more toxic to fish than two newer dry cleaning solvents: Solvon K4 and DF2000.

For more information, see The Aquatic Toxicity of Perchloroethylene Dry Cleaning Solvent (PDF) or contact Steve Whittaker at 206-263-8499 or steve.whittaker@kingcounty.gov.

Help for dry cleaners

Resources for dry cleaners

Journal articles from our program

  • Whittaker SG and Johanson CA. A health and environmental profile of the dry cleaning industry in King County, Washington. Journal of Environmental Health. 2013. Volume 75, Issue 10, pp. 4-22.
  • Whittaker SG, Taylor J, and Van Hooser LM. Characterization of "hydrocarbon" dry cleaning in King County, Washington. Journal of Environmental Health. 2015. Volume 78, Issue 2, pp. 8-13.