Guidance and information for
REDUCING WORKER EXPOSURE
TO PERCHLOROETHYLENE (PERC) IN DRY CLEANING
TO PERCHLOROETHYLENE (PERC) IN DRY CLEANING
Occupational Safety and Health Administration
Directorate of Standards and Guidance
Download PDF (499 KB)
Directorate of Standards and Guidance
Download PDF (499 KB)
This document has been prepared by the Occupational Safety and Health Administration (OSHA) to help dry cleaning establishments reduce employee exposures to perchloroethylene (also known as perc, tetrachloroethylene, C2Cl4 or Cl2C=CCl2). The dry cleaning industry has improved the control of perchloroethylene in recent years, and modern dry cleaning equipment involves much lower exposures than older style equipment. However, there is still a need to reduce employee exposure to the chemical to reduce any possible health effects that could result from long-term exposure to the chemical. Many dry cleaning employers have found that equipment design, preventive maintenance, control of leaks in equipment, proper ventilation, and good work practices can reduce perc exposure to workers, reduce costs by recovering perc for reuse, help create a cleaner environment, and help comply with federal and state environmental regulations. The document is organized into the following sections:
- Health Hazards
- Perc Exposure
- Current Regulations and Recommendations
- Machine Design and Maintenance
- PPE, Work Practices and Training
- Perc Air Monitoring
- Case Studies
Appendix B. International Chemical Safety Card for Tetrachloroethylene
This guidance document is not a standard or regulation, and it creates no new legal obligations. The Bulletin is advisory in nature, informational in content, and is intended to assist employers in providing a safe and healthful workplace. The Occupational Safety and Health Act requires employers to comply with hazard-specific safety and health standards. In addition, pursuant to Section 5(a)(1), the General Duty Clause of the Act, employers must provide their employees with a workplace free from recognized hazards likely to cause death or serious physical harm. Employers can be cited for violating the General Duty Clause if there is a recognized hazard and they do not take reasonable steps to prevent or abate the hazard. However, failure to implement these recommendations is not, in itself, a violation of the General Duty Clause. Citations can only be based on standards, regulations, and the General Duty Clause.
REDUCING WORKER EXPOSURE TO PERCHLOROETHYLENE (PERC) IN DRY CLEANING
Perchloroethylene ("perc") has long been recognized as an effective dry cleaning solvent and today it is by far the most commonly used solvent in dry cleaning shops. However, as a volatile organic solvent, perc may pose serious health hazards if exposure is not properly controlled. Dry cleaning workers who routinely breathe excessive amounts of the solvent vapor or spill perc on their skin are at risk of developing health problems.
Special precautions are recommended to avoid health risks from perc exposure. The purpose of this guidance is to provide practical and effective ways for dry cleaning operators to reduce worker exposure to perc. The guidance emphasizes reducing perc exposure through a combination of using modern equipment and preventive maintenance, control of leaks in dry cleaning equipment, proper ventilation, and good work practices.
II. Health Hazards
During dry cleaning, perc primarily enters the body from inhalation of the vapors, potentially resulting in the following health hazards:
- Dizziness, drowsiness, and loss of coordination;
- Mild loss of memory, visual perception, and reaction time after several years of exposure; or
- Redness and blistering of the skin after prolonged dermal contact.
The possibility of these health hazards can be minimized by reducing worker exposures to perc vapor and by avoiding skin contact with perc.
III. Perc Exposure
Primary Sources of Perc Exposure
Dry cleaning employees may be exposed to perc while performing both routine tasks and machine maintenance. Activities that result in elevated exposure include the following:
- Loading dirty clothes into the machine (when perc-contaminated air is displaced and forced out of the machine);
- Removing clothes, especially thick items, before the drying cycle is finished;
- For transfer machines, transferring solvent-laden clothes into the dryer;
- Cleaning lint and button traps;
- Raking out the still (distillation unit residue);
- Changing the solvent filter;
- Maintenance of water separator; and
- Handling and storage of hazardous waste.
Uncontrolled emissions, so-called "fugitive emissions," from dry cleaning machines can also expose workers to high levels of perc. These include:
- Perc emissions not captured by vapor recovery and thus released when the loading door is opened or through the vent; and
- Perc emissions from leaks in machines, hoses, valves, and ducts.
Other possible sources of perc exposure not directly associated with the dry cleaning equipment include:
- Pressing freshly dry cleaned clothes;
- Using a perc-based spotting agent; and
- Using a perc-based waterproofing agent.(1)
OSHA has set mandatory permissible exposure limits (PELs) for perc, presented in Table 1. This table also lists perc exposure limits recommended by other safety and health organizations.
Table 1. Worker Exposure Limits
for Perchloroethylene (Tetrachloroethylene)
for Perchloroethylene (Tetrachloroethylene)
|Organization||8-hour time- weighted average (TWA)
|Permissible Exposure Limit (PEL): 100 parts per million (ppm)
||Ceiling: 200 ppm (for 5 mins. in any 3-hr. period), with a maximum peak of 300 ppm
|Threshold Limit Value (TLV):
|Short-term exposure limit (STEL):
100 ppm (as a 15-min. TWA)
||Potential Occupational Carcinogen; Minimize workplace exposure concentrations.
Other OSHA standards that may apply when workers are exposed to perc include: Hazard Communication (29 CFR 1910.1200); General requirements for personal protective equipment (29 CFR 1910.132); and Respiratory Protection (29 CFR 1910.134).
In addition to these worker exposure limits, dry cleaning facilities must comply with EPA regulations controlling the release of perc into the environment - air, land, and water. EPA has developed regulations that affect many aspects of dry cleaning operations, including machine operation and maintenance, building design and ventilation, work practices, as well as perc storage and disposal. There are also EPA requirements on air monitoring for perc release, record keeping, and perc use reporting. (For further information on EPA regulations, see Plain English Guide for Perc Cleaners, EPA, 2003.)
V. Machine Design and Maintenance
Dry cleaning technology has evolved substantially over the decades. The newer machine designs (dry-to-dry, closed looped) greatly reduce the amount of perc vapor released into the air inside the shop as well as outdoors, resulting in cost savings since more perc is recovered for reuse, as well as safer working conditions and a cleaner environment.
The oldest type of dry cleaning machines - transfer machines - can expose workers to high amounts of perc, particularly during transfer of solvent-laden clothing from washer to dryer. Newer equipment (dry-to-dry machines) reduce worker exposure by eliminating this transfer step (clothes enter and exit the machine dry).
The first dry-to-dry equipment, dry-to-dry vented, exhausts residual solvent vapors either directly outside or first through a perc vapor recovery system. The present designs, dry-to-dry closed loop machines, recirculate perc rather than release it outdoors. The latest technology incorporates a secondary vapor recovery system on the dry-to-dry closed loop machines that most effectively minimizes perc usage, environmental releases, and worker exposure to perc. Figure 1, below, illustrates the perc exposure levels of machine operators associated with the various dry cleaning machines.
Replacing equipment that wears out with modern equipment can reduce exposures. Also, routine machine maintenance combined with detection and timely repair of identified leaks can be extremely effective in controlling airborne levels of perc vapor. (See the Case Studies described in Section X.) The EPA estimates that as much as 25 percent of solvent emissions can be attributed to leaks. In addition to creating unsafe airborne levels of perc, leaks are wasteful and costly. Routine machine maintenance needs to be performed to ensure optimal operation of all components. Appropriate personal protective equipment (PPE) needs to be worn during maintenance activities to ensure protection from perc hazards. (See Section VII for more information on PPE.)
Recommended machine maintenance activities include the following:
- Clean lint and button traps regularly to prevent clogging of condensers and fans.
- Rake out still daily. (Consider installing a pump that allows residue to be pumped directly to a safety can.)
- Change all filters as necessary.
- Desorb carbon adsorber before saturation point.
- Adjust refrigerated condensers to ensure proper temperature of drying air.
- Maintain and repair exhaust fans.
NEVER PERFORM MAINTENANCE WHILE DRY CLEANING EQUIPMENT IS OPERATING.
To control perc leaks from dry cleaning equipment:
- Perform daily checks for leaks in door gaskets, valves, hoses, pumps, tubing, and piping connections. Look for liquid pools and droplets on or around equipment. Unusual solvent odor may indicate a vapor leak (do not rely only on the sense of smell for detecting leaks).
- Replace gaskets before they become hard, cracked, or worn.
- Use a direct-reading air-monitoring device (see Section VIII) to detect vapor leaks in piping, exhaust ductwork, and associated components.
- Use perc-resistant seals and fittings recommended by the manufacturer of the machine.
- Repair leaks immediately.
Adequate ventilation is essential for controlling perc levels within the dry cleaning shop. General ventilation, provided by equipment such as overhead fans, is useful for reducing heat and humidity and diluting perc levels. Such ventilation can be designed to move the perc vapors away from workers and customers while continuously supplying clean, fresh air to the dry cleaning area.
Local exhaust ventilation (LEV) captures perc vapor at the source of the release, removing the vapor before it enters the air inside the shop. Well-designed LEV may be provided where perc exposure is highest, for example, at the loading door. Newer dry cleaning equipment has built-in LEV designed to prevent escape of vapors during machine loading and unloading. For machines without built-in LEV, an external ventilation hood outside the machine door can be installed to control vapors when the door is open. (A study describing this method of control is summarized in Case Study #5 in Section X.)
Detailed information regarding desirable configurations for general ventilation and LEV as well as recommendations on exhaust fan placement and capacity can be found in pamphlets by the International Fabricare Institute (IFI) (1989)(2) and NIOSH (1998)(3).
VII. PPE, Work Practices, and Training
Personal protective equipment (PPE) - including aprons, gloves, goggles, and respirators approved for use with organic chemicals - is used to help workers avoid perc exposure. Workers must wear respirators equipped with filters or cartridges specifically designed for organic vapors when elevated perc exposures are anticipated (29 CFR 1919.134). Tasks where elevated exposure may occur include machine maintenance, filter changes, waterproofing operations, and loading/unloading machines (depending on the equipment in use). Workers using transfer machines may also need to wear chemical-resistant aprons. Spotters can wear goggles, chemical-resistant aprons, and gloves. Spill cleanup workers always need to wear respirators and gloves.
Work Practices - Good work practices can greatly minimize worker exposure to perc vapors. For example, peak exposure levels can be reduced by several hundred parts per million simply by proper positioning of the worker's head and body during transfer operations. Other important work practices to reduce perc exposures are listed below.
Work Practice Tips for Dry cleaning Operators
- Do not load the machine past its capacity.
- Do not open the machine door when the cycle is running.
- Keep the machine door CLOSED as much as possible.
- Do not "shortcut" the drying cycle by removing garments from the machine before the cycle is finished.
- Keep your head and face turned away from the machine door and clothes when removing solvent-laden clothes from the washer.
- Do not transfer perc to machines by hand or with open buckets. Use a closed piping system that connects directly to the machine drum.
- WAIT until the machine and solvent are cold before performing maintenance.
- Use spotting agents sparingly.
- Use perc-free spotting agents.
- Clean up perc spills immediately. (The shop should have in place a plan for safely responding to perc spills.)
- Store containers of perc and perc wastes in tightly sealed containers.
- Position your hand away from the door when opening a transfer machine.
Training - Dry cleaning employees need training on how to protect themselves from the hazards of perc (OSHA Hazard Communication standard, 29 CFR 1910.1200). Employees should be trained in proper work practices for all of their expected tasks - operating and maintaining machines, spotting, waterproofing, housekeeping, and perc transfer and storage.
Workers must be trained on the health hazards and symptoms associated with perc exposure. Workers should become familiar with Material Safety Data Sheets (MSDS) and container labels for perc (OSHA Hazard Communication standard, 29 CFR 1910.1200). The International Chemical Safety Card for perc can be found in Appendix B of this publication to help with this training.
In addition, workers should be familiar with the location and proper use of eyewash stations as well as procedures for responding to first aid emergencies, such as eye splashes and skin contamination. OSHA requires employers to train their employees about hazards and methods to prevent exposure to chemicals used in the workplace (OSHA Hazard Communication standard, 29 CFR 1910.1200). Workers must also be trained on the proper use of respirators (Respiratory Protection standard, 29 CFR 1910.134).
VIII. Perc Air Monitoring A variety of devices and instruments are available to measure perc levels in the air. Reasons for performing air monitoring include:
- To determine the perc exposure levels of individual employees;
- To identify sources of leaks in equipment; and
- To measure perc levels before and after modifications to equipment or procedures.
The samples are then sent to a qualified laboratory to analyze the perc concentration. The results can be compared with the OSHA PEL and other recommended exposure limits for perc (listed in Table 1).
For detecting equipment leaks and other emissions, portable, direct-reading devices provide either a visual/audible indication of a leak or an instantaneous measurement of the perc vapor concentration at the source of the emission. These instruments vary in terms of cost, accuracy, and ease of use.
Two relatively inexpensive, easy to use leak- detection devices are:
- Small, hand-held refrigerant leak detectors that indicate a perc leak by a visual and audible signal; and
- Colorimetric detector tubes (used with small, hand-operated pumps) that change color depending on the perc vapor concentration.
OSHA has a free consultation service for small and medium-sized businesses with hazardous operations. The service is confidential and offers the expertise of qualified occupational safety and health professionals to employers who request advice and assistance. OSHA consultation is available in all 50 States, the District of Columbia, Guam, Puerto Rico, the Northern Mariana Islands and the Virgin Islands. Information on OSHA consultation services can be found at: www.osha.gov/dcsp/smallbusiness/consult.html.
For assistance with perc monitoring, consult your perc supplier's product stewardship program or a professional dry cleaning association, such as the International Fabricare Institute. If you need the technical expertise of an industrial hygienist, the American Industrial Hygiene Association (AIHA) offers a listing of qualified consultants at: http://www.aiha.org/ConsultantsConsumers/html/consultantsclient.asp.
X. Case Studies
Dry cleaning shop owners have numerous options available for reducing the perc exposures of their employees. The case studies below describe the effectiveness of measures such as installing relatively low-cost machine retrofits, installing LEV, and performing routine machine maintenance and leak detection.
Case Study #1: Emission Control Retrofit - Carbon Adsorber
Installing a new carbon adsorber on a dry cleaning machine reduced the perc exposures of operators by 92 percent, according to a NIOSH study. The 60-pound closed-loop carbon adsorber was installed to remove residual perc not collected by the existing refrigerated condenser on the closed-loop, dry-to-dry machine. The retrofit cost less than $5,000.
Before the retrofit, the average perc exposure of operators during the one-minute machine loading and unloading process was 353 ppm. After the carbon adsorber was installed, the average exposure was 29 ppm, a reduction of approximately 92 percent.
Case Study #2: Emission Control Retrofit - Refrigerated Condenser
A NIOSH study found that perc exposures of dry cleaning machine operators were reduced by 60 percent after a refrigerated condenser was installed on a dry cleaning machine.
A 5-ton cooling capacity refrigerated condenser was installed on a vented, dry-to-dry machine in place of its original water-cooled condenser and single-pass carbon adsorber. The retrofit cost less than $5,000. Before the installation of the refrigerated condenser, the average perc exposure of machine operators during the one-minute machine loading and unloading phase was 1,139 ppm. After the retrofit, the average exposure was 456 ppm, a reduction of about 60 percent. NIOSH cautioned that only dry cleaning machines in good repair with few leaks should be considered for retrofitting. Although this technology significantly reduced perc exposure in this case, it does not eliminate it and additional controls would be needed to achieve further reductions.
Case Study #3: Gasket Leak - Detection and Repair
Repairing a leaking gasket on a dry cleaning machine resulted in a full-shift perc exposure reduction of 22 ppm, according to a NIOSH study of retrofit emission controls (described further in Case Study #2). The gasket at the rear of the machine being retrofitted with a new refrigerated condenser sprung a leak during the installation. Before the retrofit, TWA perc concentrations averaged 47 ppm. Measurements taken after the leak was fixed resulted in an average perc exposure of 25 ppm.
Case Study #4: Distillation Unit Leak - Detection and Repair
During the LEV evaluation (described in Case Study #5), NIOSH noted that the full-shift perc exposures of machine operators were up to four times higher on the day when the distillation unit was operating (about 20 ppm vs. 5 ppm when the unit was turned off). These elevated readings led to the identification and repair of a leak in the distillation system. If perc monitoring had not been conducted, the leak might not have been detected. This study underscores the importance of routine perc air monitoring to identify and repair equipment leaks.
Case Study #5: Local Exhaust Ventilation
A NIOSH study showed that installation of a simple, inexpensive LEV system was effective in reducing average full-shift TWA perc exposures of machine operators by 37 percent.
Before the LEV installation, the average full-shift perc exposure was 4.7 ppm. The 12-year-old dry cleaning machine was a dry-to-dry, closed-loop design with a 50-pound capacity. The LEV system, including fabrication, installation, and electric wiring, was installed for $2,560. The LEV was positioned directly above the dry cleaning machine door and exhausted air from in front of the door only when the door was opened. The average perc exposure was reduced by about 37 percent, to 3.0 ppm, after the LEV installation.
Appendix A. Recommended Maintenance Schedule for Dry Cleaning Machines
Daily Maintenance Tasks
- Clean button trap strainer and lint bag.
- Dispose of contaminated water from the water separator.
- Desorb the carbon adsorber.
- Rake out the still of the distillation unit (or weekly as needed).
- Check door seatings and gaskets of machine cylinder for liquid and vapor leaks.
- Check the button trap for lid leaks.
- Launder the lint bag.
- Check seals and gaskets of the refrigerated condenser's diverter valve, distillation unit, filters, filter housings, and muck cooker for liquid and vapor leaks.
- Rake out the still of the distillation unit (or daily as needed).
- Clean the separator tank of the water separator and perform leak checks.
- Measure the exhaust temperature of the refrigerated condenser.
- Measure perc in the exhaust system.
- Perform leak checks on hose and pipe connections, fittings, couplings, and valves.
- Check the exhaust damper (vented machines) for liquid and vapor leaks.
- Check for lint buildup on the heating and condensing coils and refrigerated condenser coils.
- Check for leaks in the ductwork of the lint trap and carbon adsorber.
- Check for lint buildup on the temperature probe of the lint trap.
- Clean the vent of the water separator.
- Clean the muck cooker's steam and condensation coils.
- Clean the heating/condensing and refrigerated condenser coils.
- Clean and change filters according to the manufacturer's schedule.
Appendix B. International Chemical Safety Card for Tetrachloroethylene
The following International Chemical Safety Card (ICSC) for tetrachloroethylene was published in 2000. The ICSCs project is an undertaking of the International Programme on Chemical Safety (IPCS). The project is being developed in cooperation between the IPCS and the Commission of the European Communities. The IPCS is a joint activity of three cooperating international organizations: the United Nations Environment Programme (UNEP), the International Labour Office (ILO) and the World Health Organization (WHO). The main objective of the IPCS is to carry out and disseminate evaluations of the hazards posed by chemicals to human health and the environment.
ICSC cards summarize essential health and safety information on chemicals for their use at the shop floor level by workers and employers. Cards are available for over 1,300 chemicals, and they are provided in several languages, including English, Korean, Spanish, Russian, French, German, Japanese and Chinese.
To access the most recent ICSC card for perc, to locate the perc card in another language, or to find the card for another chemical, access the NIOSH Internet site at: http://www.cdc.gov/niosh/ipcsneng/neng0076.html.
International Chemical Safety Cards
1,1,2,2-TetrachloroethyleneICSC # 0076
C2Cl4 / Cl2C=CCl2
Molecular mass: 165.8
CAS # 127-18-4
UN # 1897
EC # 602-028-00-4
|TYPES OF HAZARD/ EXPOSURE||ACUTE HAZARDS/ SYMPTOMS||PREVENTION||FIRST AID/
|FIRE||Not combustible. Gives off irritating or toxic fumes (or gases) in a fire.||In case of fire in the surroundings: all extinguishing agents allowed.|
|EXPOSURE||STRICT HYGIENE! PREVENT GENERATION OF MISTS!|
|•INHALATION||Dizziness. Drowsiness. Headache. Nausea. Weakness. Unconsciousness.||Ventilation, local exhaust, or breathing protection.||Fresh air, rest. Artificial respiration if indicated. Refer for medical attention.|
|•SKIN||Dry skin. Redness.||Protective gloves. Protective clothing.||Remove contaminated clothes. Rinse and then wash skin with water and soap.|
|•EYES||Redness. Pain.||Safety goggles, face shield.||First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then take to a doctor.|
|•INGESTION||Abdominal pain (further see Inhalation).||Do not eat, drink, or smoke during work.||Rinse mouth. Do NOT induce vomiting. Give plenty of water to drink. Rest.|
|SPILLAGE||STORAGE||PACKAGING & LABELLING|
|Ventilation. Collect leaking and spilled liquid in sealable containers as far as possible. Absorb remaining liquid in sand or inert absorbent and remove to safe place. Do NOT let this chemical enter the environment. (Extra personal protection: filter respirator for organic gases and vapours).||Separated from metals ( see Chemical Dangers ), food and feedstuffs . Keep in the dark. Ventilation along the floor.||Do not transport with food and feedstuffs.
UN Hazard Class: 6.1
UN Packing Group: III
|SEE IMPORTANT INFORMATION ON BACK|
|The substance is toxic to aquatic organisms. The substance may cause long-term effects in the aquatic environment.|
|N O T E S|
|Depending on the degree of exposure, periodic medical examination is indicated. The odour warning when the exposure limit value is exceeded is insufficient. Do NOT use in the vicinity of a fire or a hot surface, or during welding. An added stabilizer or inhibitor can influence the toxicological properties of this substance, consult an expert.
Footnote 1 Use of perc-based spotting or waterproofing agents is not current practice in the dry cleaning industry. However, these operations are addressed in this document for those few dry cleaning establishments that may continue to use these products. (Back to text)
Footnote 2 IFI. 1989. Reducing Vapor Exposure: OSHA compliance. International Fabricare Institute. Vol. 13, No. # 5. (Back to text)
Footnote 3 NIOSH. 1998. Control of Exposure to Perchloroethylene in Commercial Drycleaning. NIOSH Hazard Controls. DHHS (NIOSH) Publication No. 97-154. http://www.cdc.gov/niosh/hc16.html (Back to text)