Washington Administrative Code › Title 296 - Labor and Industries, Department of › Chapter 296-62 - General occupational health standards › Part G - CARCINOGENS (SPECIFIC) › Section 296-62-07477 - Appendix C

Current through Register Vol. 24-14, July 15, 2024
Questions and Answers
Methylene Chloride Control in Furniture Stripping
(Adapted from NIOSH publication No. 93-133)
Introduction
This appendix answers commonly asked questions about the
				  hazards from exposure to methylene chloride. It also describes approaches to
				  controlling methylene chloride exposure during the most common furniture
				  stripping processes. Although these approaches were developed and field tested
				  by the National Institute of Occupational Safety and Health, each setting
				  requires custom installation because of the different air flow interferences at
				  each site.
1.What is the Stripping Solution Base?
The most common active ingredient in paint removers is a
				  chemical called methylene chloride. Methylene chloride is present in the paint
				  remover to penetrate, blister, and finally lift the old finish. Other chemicals
				  in paint removers work to accelerate the stripping process, to retard
				  evaporation, and to act as thickening agents. These other ingredients may
				  include: methanol, toluene, acetone, or
				  paraffin.
1
2.Is Methylene Chloride Bad for Me?
Exposure to methylene chloride may cause short-term health
				  effects or long-term health effects.
Short-Term (Acute) Health Effects
Exposure to high levels of paint removers over short periods
				  of time can cause irritation to the skin, eyes, mucous membranes, and
				  respiratory tracts. Other symptoms of high exposure are dizziness, headache,
				  and lack of coordination. The occurrence of any of these symptoms indicates
				  that you are being exposed to high levels of methylene chloride. At the onset
				  of any of these symptoms, you should leave the work area, get some fresh air,
				  and determine why the levels were high.
A portion of inhaled methylene chloride is converted by the
				  body to carbon monoxide, which can lower the blood's ability to carry oxygen.
				  When the solvent is used properly, however, the levels of carbon monoxide
				  should not be hazardous. Individuals with cardiovascular or pulmonary health
				  problems should check with their physician before using the paint stripper.
				  Individuals experiencing severe symptoms such as shortness of breath or chest
				  pains should obtain proper medical care
				  immediately.
1
Long-Term (Chronic) Health Effects
Methylene chloride has been shown to cause cancer in certain
				  laboratory animal tests. The available human studies do not provide the
				  necessary information to determine whether methylene chloride causes cancer in
				  humans. However, as a result of the animal studies, methylene chloride is
				  considered a potential occupational carcinogen. There is also considerable
				  indirect evidence to suggest that workers exposed to methylene chloride may be
				  at an increased risk of developing ischemic heart disease. Therefore, it is
				  prudent to minimize exposure to solvent
				  vapors.
3
3.What does the Methylene Chloride Standard Require?
On January 10, 1997, the Occupational Safety and Health
				  Administration published a new regulation for methylene chloride. The standard
				  establishes an eight-hour time-weighted average exposure limit of 25 parts per
				  million (ppm), as well as a short-term exposure limit of 125 ppm determined
				  from a 15 minute sampling period. That is a reduction from the current WISHA
				  limit of 100 ppm. The standard also sets a 12.5 ppm action level (a level that
				  would trigger periodic exposure monitoring and medical surveillance
				  provisions).
2
WISHA adopted an
				  identical standard on [
date
].
The National Institute for Occupational Safety and Health
				  recommends that methylene chloride be regarded as a "potential occupational
				  carcinogen." NIOSH further recommends that occupational exposure to methylene
				  chloride be controlled to the lowest feasible limit. This recommendation was
				  based on the observation of cancers and tumors in both rats and mice exposed to
				  methylene chloride in air.
5
4.How Can I Be Exposed to Methylene Chloride while Stripping
				  Furniture?
Methylene chloride can be inhaled when vapors are in the air.
				  Inhalation of the methylene chloride vapors is generally the most important
				  source of exposure. Methylene chloride evaporates quicker than most chemicals.
				  The odor threshold of methylene chloride is 300 ppm.
6
Therefore, once you smell methylene chloride, you are
				  being over-exposed. Pouring, moving, or stirring the chemical will increase the
				  rate of evaporation.
Methylene chloride can be absorbed through the skin either by
				  directly touching the chemical or through your gloves. Methylene chloride can
				  be swallowed if it gets on your hands, clothes, or beard, or if food or drinks
				  become contaminated.
5.How Can Breathing Exposures be Reduced?
Install a Local Exhaust Ventilation System
Local exhaust ventilation can be used to control exposures.
				  Local exhaust ventilation systems capture contaminated air from the source
				  before it spreads into the workers' breathing
				  zone.
7
If engineering controls are not
				  effective, only a self-contained breathing apparatus equipped with a full face
				  piece and operated in a positive-pressure mode or a supplied-air respirator
				  affords the level of protection. Air-purifying respirators such as gas masks
				  with organic vapor canisters can only be used for escape
				  situations.
8
These gas masks are not
				  suitable for normal work situations because methylene chloride is poorly
				  absorbed by the canister filtering material.
A local exhaust system consists of the following: a hood, a
				  fan, ductwork, and a replacement air
				  system.
9,10,11
Two processes are
				  commonly used in furniture stripping: Flow-over and dip tanks. For flow-over
				  systems there are two common local exhaust controls for methylene chloride - a
				  slot hood and a down draft hood. A slot hood of different design is most often
				  used for dip tanks. (See Figures 1, 2, and 3.)
The hood is made of sheet metal and connected to the tank.
				  All designs require a centrifugal fan to exhaust the fumes, ductwork connecting
				  the hood and the fan, and a replacement air system to bring conditioned air
				  into the building to replace the air exhausted.
In constructing or designing a slot or down draft hood, use
				  the following data:
Click to view
								image
FIGURE 1 -- SLOT HOOD
Click to view
				  image
FIGURE 1 -- SLOT HOOD
Click to view
								image
FIGURE 2 -- DOWNDRAFT HOOD
Click to view
				  image
FIGURE 2 -- DOWNDRAFT HOOD
Click to view
								image
FIGURE 3 -- SLOT HOOD FOR DIP
								TANK
Click to view
				  image
FIGURE 3 -- SLOT HOOD FOR DIP TANK
Safe Work Practices
Workers can lower exposures by decreasing their access to the
				  methylene chloride.
12
1 Turn on dip tank control system several minutes before
				  entering the stripping area.
2 Avoid unnecessary transferring or moving of the stripping
				  solution.
3 Keep face out of the air stream between the
				  solution-covered furniture and the exhaust system.
4 Keep face out of vapor zone above the stripping solution
				  and the dip tank.
5 Retrieve dropped items with a long handled tool.
6 Keep the solution-recycling system off when not in use.
				  Cover reservoir for recycling system.
7 Cover dip tank when not in use.
8 Provide adequate ventilation for rinse area.
How Can Skin Exposures Be Reduced?
Skin exposures can be reduced by wearing gloves whenever you
				  are in contact with the stripping
				  solution.
13
1 Two gloves should be worn. The inner glove should be made
				  from polyethylene/ethylene vinyl alcohol (e.g., Silver Shield¦, or
				  4H¦). This material, however, does not provide good physical resistance
				  against tears, so an outer glove made from nitrile or neoprene should be
				  worn.
2 Shoulder-length gloves will be more protective.
3 Change gloves before the break-through time occurs. Rotate
				  several pairs of gloves throughout the day. Let the gloves dry in a warm well
				  ventilated area at least over night before reuse.
4 Keep gloves clean by rinsing often. Keep gloves in good
				  condition. Inspect the gloves before use for pin-holes, cracks, thin spots, and
				  stiffer than normal or sticky surfaces.
5 Wear a face shield or goggles to protect face and
				  eyes.
6.What Other Problems Can Occur?
Stripping Solution Temperature
Most manufacturers of stripping solution recommend
				  controlling the solution to a temperature of 70°F. This temperature is
				  required for the wax in the solution to form a vapor barrier on top of the
				  solution to keep the solution from evaporating too quickly. If the temperature
				  is too high, the wax will not form the vapor barrier. If it is too cold, the
				  wax will solidify and separate from the solvent causing increased evaporation.
				  Use a belt heater to heat the solution to the correct temperature. Call your
				  solution manufacturer for the correct temperature for your
				  solution.
14
Make-Up Air
Air will enter a building in an amount to equal the amount of
				  air exhausted whether or not provision is made for this replacement. If a local
				  exhaust system is added a make-up or replacement air system must be added to
				  replace the air removed. Without a replacement air system, air will enter the
				  building through cracks causing uncontrollable eddy currents. If the building
				  perimeter is tightly sealed, it will prevent the air from entering and severely
				  decrease the amount exhausted from the ventilation system. This will cause the
				  building to be under negative pressure and decrease the performance of the
				  exhaust system.
15
Dilution Ventilation
With general or dilution ventilation, uncontaminated air is
				  moved through the workroom by means of fans or open windows, which dilutes the
				  pollutants in the air. Dilution ventilation does not provide effective
				  protection to other workers and does not confine the methylene chloride vapors
				  to one area.
16
Phosgene Poisoning from Use of Kerosene Heaters
Do not use kerosene heaters or other open flame heaters while
				  stripping furniture. Use of kerosene heaters in connection with methylene
				  chloride can create lethal or dangerous concentrations of phosgene. Methylene
				  chloride vapor is mixed with the air used for the combustion of kerosene in
				  kerosene stoves. The vapor thus passes through the flames, coming into close
				  contact with carbon monoxide at high temperatures. Any chlorine formed by
				  decomposition may, under these conditions, react with carbon monoxide and form
				  phosgene.
17
REFERENCES
1
Halogenated Solvents
				  Industry Alliance and Consumer Product Safety Commission [1990]. Stripping
				  Paint from Wood (Pamphlet for consumers on how to strip furniture and
				  precautions to take). Washington DC: Consumer Product Safety Commission.
2
Ibid.
3
NIOSH [1992]. NIOSH
				  Testimony on Occupational Safety and Health Administration's proposed rule on
				  occupational exposure to methylene chloride, September 21, 1992, OSHA Docket
				  No. H-71. NIOSH policy statements. Cincinnati, OH: U.S. Department of Health
				  and Human Services, Public Health Service, Centers for Disease Control,
				  National Institute for Occupational Safety and Health.
4
56 Fed. Reg. 57036
				  [1991]. Occupational Safety and Health Administration: Proposed rule on
				  occupational exposure to methylene chloride.
5
NIOSH [1992].
6
Kirk, R.E. and P.F.
				  Othmer, Eds. [1978]. Encyclopedia of Chemical Technology, 3rd Ed., Vol. 5:690.
				  New York: John Wiley & Sons, Inc.
7
ACGIH [1988].
				  Industrial Ventilation: A Manual of Recommended Practice. 20th Ed. Cincinnati,
				  OH: American Conference of Governmental Industrial Hygienists.
8
NIOSH [1992].
9
Fairfield, C.L. and
				  A.A. Beasley [1991]. In-depth Survey Report at the Association for Retarded
				  Citizens, Meadowlands, PA. The Control of Methylene Chloride During Furniture
				  Stripping. Cincinnati, OH: U.S. Department of Health and Human Services, Public
				  Health Service, Centers for Disease Control, National Institute for
				  Occupational Safety and Health.
10
Fairfield, C.L.
				  [1991]. In-depth Survey Report at the J.M. Murray Center, Cortland, NY. The
				  Control of Methylene Chloride During Furniture Stripping. Cincinnati, OH: U.S.
				  Department of Health and Human Services, Publish Health Service, Centers for
				  Disease Control, National Institute for Occupational Safety and Health.
11
Hall, R.M., K.F.
				  Martinez, and P.A. Jensen [1992]. In-depth Survey Report at Tri-County
				  Furniture Stripping and Refinishing, Cincinnati, OH. The Control of Methylene
				  Chloride During Furniture Stripping. Cincinnati, OH: U.S. Department of Health
				  and Human Services, Public Health Service, Centers for Disease Control,
				  National Institute for Occupational Safety and Health.
12
Fairfield, C.L. and
				  A.A. Beasley [1991]. In-depth Survey Report at the Association for Retarded
				  Citizens, Meadowlands, PA. The Control of Methylene Chloride During Furniture
				  Stripping. Cincinnati, OH: U.S. Department of Health and Human Service, Centers
				  for Disease Control, National Institute for Occupational Safety and
				  Health.
13
Roder, M. [1991].
				  Memorandum of March 11, 1991 from Michael Roder of the Division of Safety
				  Research to Cheryl L. Fairfield of the Division of Physical Sciences and
				  Engineering, National Institute for Occupational Safety and Health, Centers for
				  Disease Control, Public Health Service, U.S. Department of Health and Human
				  Services.
14
Kwick Kleen
				  Industrial Solvents, Inc., [1981]. Operations Manual, Kwick Kleen Industrial
				  Solvents, Inc., Vincennes, IN.
15
ACGIH
				  [1988].
16
Ibid.
17
Gerritsen, W.B. and
				  C.H. Buschmann [1960]. Phosgene Poisoning Caused by the Use of Chemical Paint
				  Removers containing Methylene Chloride in Ill-Ventilated Rooms Heated by
				  Kerosene Stoves. British Journal of Industrial Medicine
17
:187.
Statutory Authority:
					 RCW
					 49.17.040, [49.17].050,[49.17].060 .
					 98-10-029, § 296-62-07477, filed 4/24/98, effective 7/24/98; 97-18-062,
					 § 296-62-07477, filed 9/2/97, effective 12/1/97.
Reviser's note:
The brackets and enclosed
					 material in the text of the above section occurred in the copy filed by the
					 agency.