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WOODWORKING HAZARDS
By Michael McCann, Ph.D., C.I.H. and Angela Babin, M.S.
Wood is one of the most commonly used material in art, crafts,
and home hobbies. Wood is used for framing and installations, as
well as in the creation of sculpture, furniture, crafts, jewelry,
theatrical props and more. Woodworking involves techniques such
as carving, laminating, joining, sawing, sanding, paint removing,
and painting and finishing.
WOOD HAZARDS
Wood sculpture and furniture-making use a large number of
different types of hard and soft woods, including many exotic
tropical woods. Many of these woods are hazardous themselves.
Sometimes woods are treated with hazardous preservatives or
pesticides.
HARDWOODS
Hardwoods are commonly used in wood sculpture and furniture
making. Many rare hardwoods are imported from tropical
countries. In recent years, there has been considerable
controversy in the woodworking community about the ethics of
using rare tropical hardwoods in sculpture because the market for
them is contributing to deforestation of many parts of the world.
Hazards
1. Saps present in many green woods, and lichens and liverworts
present on the surface of freshly cut wood, can cause skin allergies and
irritation from direct contact.
2. Many hardwood dusts, especially those from exotic woods, are
common sensitizers and can cause allergic skin reactions. Some
hardwoods can cause allergic reactions in individuals working
with or using finished hardwoods. Prolonged contact with
rosewood, for example, which was used in making musical
instruments, has caused allergic reactions in some musicians.
3. Contact with the dust of many hardwoods can cause
conjunctivitis (eye inflammation), hay fever, asthma, coughing,
and other respiratory diseases. Canadian and Western Red Cedar
are examples.
4. Some hardwoods can cause hypersensitivity pneumonia
(alveolitis), and frequent attacks can cause permanent lung
scarring (fibrosis). Examples of these highly toxic woods
include giant sequoia, cork oak, some maple woods and redwood.
5. Some hardwoods contain chemicals that are toxic, and can cause
a variety of symptoms, including headaches, salivation, thirst,
giddiness, nausea, irregular heartbeat, etc. A classic example
is hemlock.
6. Inhalation of hardwood dust is associated with a particular
type of nasal and nasal sinus cancer (adenocarcinoma). This type
of cancer has a latency period of 40-45 years, and occurs to the
extent of about 7 in 10,000 among woodworkers who are heavily
exposed. This rate is many times higher than the rate of nasal
adenocarcinoma in the general population. Over half of all known
cases of this type of cancer are found in woodworkers.
7. See table 1. for information on specific woods. Hardwoods
such as beech and oak have been assigned a Threshold Limit Value
(TLV) from the American Conference of Governmental Industrial
Hygienists (ACGIH) of 1 mg/m3.
Precautions
1. Whenever possible, use common hardwoods rather than rare
tropical hardwoods.
2. If you have a history of allergies, you should avoid common
sensitizing woods.
3. Do not use sensitizing woods for utilitarian objects where
people would be in frequent contact with the wood. For example,
don't use these types of wood for handles.
4. Avoid inhalation of wood dusts by using local exhaust
ventilation, or wearing a NIOSH-approved toxic dust respirator.
5. If you are handling woods that can cause skin irritation or
allergies, wear gloves or apply a barrier cream. Wash hands
carefully after work.
6. See also precautions for particular woodworking processes
described below.
SOFTWOODS
Softwoods, for example pine, are often used in furniture
making. Domestic softwoods are the most common.
Hazards
1. Softwoods do not cause as high a frequency of skin and
respiratory problems as do hardwoods. A few individuals can
develop allergic reactions to some softwoods.
2. It is not known whether softwood dust also causes nasal and
nasal sinus cancer, since epidemiological studies involving
softwood often entail exposure to hardwoods and softwoods. 3.
Softwoods have been assigned a TLV of 5 mg/m3.
Precautions
1. See precautions listed for hardwoods.
PLYWOOD AND COMPOSITION BOARD
Plywood is made by gluing thin sheets of wood together with
either urea-formaldehyde glues (for indoor use) or phenol-
formaldehyde glues (for outdoor use). Composition board, for
example particle board, is made by gluing wood dust, chips, etc.
together with urea-formaldehyde resins. The materials can emit
unreacted formaldehyde for some years after manufacture, with
composition board emitting more formaldehyde. In addition,
heating these materials or machining them can cause decomposition
of the glue to release formaldehyde. In the last few years,
manufacturers of plywood and composition boards have tried to
formulate them to reduce formaldehyde emissions. However, you
often have to specify low formaldehyde plywood to ensure you get
the proper product.
Hazards
1. Formaldehyde is highly toxic by inhalation, highly toxic by
eye contact and ingestion, and moderately toxic by skin contact.
It is an irritant and strong sensitizer. Formaldehyde is a
probable human carcinogen. Even trace amounts of free
formaldehyde may cause allergic reactions in people who are
already sensitized to it.
2. Machining, sanding, or excessive heating of plywood or
composition board can cause decomposition releasing formaldehyde,
carbon monoxide, hydrogen cyanide (in the case of amino resins)
and phenol (in the case of phenol-formaldehyde resins).
Precautions
1. Use low-formaldehyde products whenever possible. There are
particle boards that are made without formaldehyde, but these are
very expensive.
2. Do not store large amounts of plywood or composition board in
the shop since it will emit formaldehyde. Instead store in a
ventilated area where people do not work.
3. Dust collectors connected to woodworking machines should be
exhausted to the outside since emitted formaldehyde will not be
captured by dust collectors.
4. A gradual bakeout, in which temperatures are raised to about
90øF, and contaminated air exhausted to the outside, may
accelerate formaldehyde emissions in already purchased particle
board and plywood, therefore reducing the exposure.
WOOD PRESERVATIVES AND OTHER TREATMENTS
Pesticides and preservatives are often applied to wood when it
is being timbered, processed or shipped. Unfortunately, it is
hard to find out what chemicals, if any, have been added. This
is especially a problem with imported woods, since pesticides and
wood preservatives banned in the United States and Canada are
often used in other countries. Pentachlorophenol and its salts,
creosote, and chromated copper arsenate (CCA) have been banned
for sale in the United Sates as wood preservatives because of
their extreme hazards. They can, however, still be found in
older woods and chromated copper arsenate is still allowed as a
commercial treatment (e.g. "green" lumber, playground equipment,
and other outdoor uses). It is supposed to be labeled. A variety
of other chemicals can be used in treating wood including fire
retardants, bleaches, etc.
Hazards
1. Pentachlorophenol is highly toxic by all routes of entry. It
can be absorbed through the skin, cause chloracne (a severe form
of acne) and liver damage, and is a probable human carcinogen and
reproductive toxin.
2. Chromated copper arsenate is extremely toxic by inhalation and
ingestion, and highly toxic by skin contact. It is a known human
carcinogen and teratogen. Skin contact can cause skin irritation
and allergies, skin thickening and loss of skin pigmentation,
ulceration, and skin cancer. Inhalation can cause respiratory
irritation, and skin, lung and liver cancer. Inhalation or
ingestion may cause digestive disturbances, liver damage,
peripheral nervous system damage, and kidney and blood damage.
Acute ingestion may be fatal.
3. Creosote has a tarry look, and is also used for outdoor wood.
It is a strong skin and respiratory irritant, and is a probable
human carcinogen and teratogen.
4. Zinc and copper naphthenate are slight skin irritants; copper
naphthenate is moderately toxic by ingestion. If suspended in
solvents, the solvent would be the main hazard.
Precautions
1. Obtain Material Safety Data Sheets on all chemicals being used
in wood treatment. Treated wood itself does not have Material
Safety Data Sheets, so you have to try and find out about any
treatments from the supplier. In the United States, CCA-treated
wood is required to have a label and information on safe
handling.
2. Do not handle woods that have been treated with
pentachlorophenol or creosote. Avoid scrap or old woods of
unknown origin.
3. Do not saw, sand or otherwise machine CCA-treated wood, if at
all possible. If you do, use with local exhaust ventilation or
wear a NIOSH-approved respirator with high efficiency (HEPA)
filters.
4. If you add wood preservatives yourself, use zinc or copper
naphthenates, if possible.
5. Do not burn wood that has been treated with creosote,
pentachlorophenol or chromated copper arsenate.
CARVING AND MACHINING WOOD
Woods can be hand carved with chisels, rasps, files, hand saws,
sandpaper, and the like, or they can be machined with electric
saws, sanders, drills, lathes and other woodworking machines.
Hazards
1. As discussed in the section on Wood Hazards, many wood dusts
are hazardous by skin contact or inhalation.
2. Woodworking machines are often very noisy, with noise levels
ranging as high as 115 dB. This can cause permanent
hearing loss with long-term exposure. The noise is often
increased with old machinery with worn parts and poor
maintenance.
3. Woodworking machinery and tools also present physical hazards
from accidents. Machinery accidents are often due to missing
machine guards, faulty equipment, or using the wrong type of
machine for a particular operation. Tool accidents are often
caused by dull tools or improper use.
4. Vibrating tools, for example chain saws, can cause "white
fingers" (Raynaud's phenomenon) involving numbness of the fingers
and hands. This can lead to permanent damage.
5. Electrical equipment can also present electrical shock and
fire hazards from faulty or inadequate wiring.
6. Sawdust and wood are fire hazards. In addition, fine sawdust
is an explosion hazard if enclosed.
Precautions
1. Equip woodworking machines that create substantial amounts of
sawdust with dust collectors. Portable dust collectors are
available that can connect to several machines. A possible
alternative is to connect the machine being used to an industrial
vacuum cleaner. Make sure that the connection from the dust
collector to the machine is as tight as possible.
2. If you cut or machine particle board or plywood, the dust
collector should be located outside.
3. Wear a NIOSH-approved toxic dust respirator when it is not
possible to use a local exhaust system.
4. Vacuum all sawdust after work; avoid dry sweeping. Clean wood
dust from around and inside machines to avoid fire hazards.
5. Wear goggles when using machines that create dust. For lathes
and similar machines which may produce wood chips, use a face
shield and goggles, and make sure the machines are properly
shielded.
6. Shield noisy machines whenever possible. Mount the machinery
with vibration isolators (like shock absorbers), and keep all
machinery in good working condition. Replace old, noisy
machinery whenever possible. Hearing protection such as ear
plugs or ear muffs may be necessary.
7. Make sure that all woodworking machines are equipped with
proper guards to prevent accidents. Use the proper machine for
particular operations and repair defective machines immediately.
Do not wear ties, long loose hair, loose sleeves, necklaces, long
earrings or other items that could catch in the machinery.
8. Keep hand tools sharpened, and cut away from your body. Do
not place your hands in front of the tool.
9. The woodshop should be equipped with panic buttons that can
shut off all machines immediately in an emergency.
10. Keep all electrical equipment and wiring in good repair, and
avoid extension cords which can be tripped over and are
electrical hazards.
GLUING WOOD
A variety of glues are used for laminating and joining wood.
These include contact adhesives, casein glue, epoxy glues,
formaldehyde-resin glues (e.g., formaldehyde-resorcinol), hide
glues, and white glue (polyvinyl acetate emulsion), and the
cyanoacrylate "instant" glues.
Hazards
1. Epoxy glues are moderately toxic by skin and eye contact, and
by inhalation. Amine hardeners (as well as other types of
hardeners) can cause skin allergies and irritation in a high
percentage of the people using them. Inhalation can cause asthma
and other lung problems.
2. Cyanoacrylate glues: These are moderately toxic by skin or
eye contact. They can glue the skin together or glue the skin
and other materials together, sometimes requiring surgical
separation. Eye contact can cause severe eye irritation. Their
long term hazards are not well studied, especially with respect
to inhalation.
3. Formaldehyde-resin glues: Resorcinol-formaldehyde and urea-
formaldehyde glues are highly toxic by eye contact and by
inhalation, and moderately toxic by skin contact. The
formaldehyde can cause skin and respiratory irritation and
allergies, and is a known human carcinogen. The resin components
may also cause irritation. Even when cured, any unreacted
formaldehyde may cause skin irritation and sanding may cause
decomposition of the glue to release formaldehyde. Formaldehyde
can be a problem when working with fiber-board and plywood.
4. Contact adhesives: Extremely flammable contact adhesives
contain hexane, which is highly toxic by chronic inhalation,
causing peripheral nerve damage. Other solvents in contact
adhesives are mineral spirits or naphtha, and 1,1,1-
trichloroethane (methyl chloroform), which are moderately toxic
by skin contact, inhalation and ingestion.
5. Water-based glues: Water-based contact adhesives, casein
glues, hide glues, white glue (polyvinyl acetate), and other
water-based adhesives are slightly toxic by skin contact, and not
significantly or only slightly toxic by inhalation or ingestion.
6. Dry casein glues: These are highly toxic by inhalation or
ingestion, and moderately toxic by skin contact since they often
contain large amounts of sodium fluoride and strong alkalis.
Precautions
1. Avoid formaldehyde resin glues because of allergic reactions
and the carcinogenicity of formaldehyde.
2. Use water-based glues rather then solvent-type glues whenever
possible.
3. Wear gloves or barrier creams when using epoxy glues, solvent-
based adhesives, or formaldehyde-resin glues.
4. Epoxy glues, cyanoacrylate glues, and solvent-based
glues should be used with good dilution ventilation, for example,
a window exhaust fan. Large amounts of these glues would need
local exhaust ventilation.
5. When using solvent-based glues - particularly those with
flammable solvents - do not smoke or allow open flames in the
studio. Eliminate other sources of ignition in the room. 6. Wear
gloves, goggles, and a NIOSH-approved toxic dust mask when mixing
dry casein glues.
PAINT STRIPPING
Stripping old paint and varnish from wood and furniture is
done with paint and varnish removers containing a wide variety of
solvents. One major class of paint and varnish removers formerly
contained benzol (benzene). Now the benzene has been replaced
with toluene. "Nonflammable" paint strippers contain methylene
chloride. They may also contain many other solvents, including
acetone, glycol ethers, methyl alcohol, and acetates. In recent
years, a safer paint stripper based on dimethyl adipate has been
developed by 3M Company. Caustic soda, acids, blowtorches and
heat guns are also used to remove old paint. Old stains on wood
are often removed with bleaches, which can contain caustic soda,
hydrogen peroxide, oxalic acid, or hypochlorite.
Hazards
1. Methylene chloride is highly toxic by inhalation, and
moderately so by skin contact. It is converted to carbon
monoxide in the body and can cause changes in heart rhythm and
possible fatal heart attacks. Smokers and people with heart
problems are especially at risk. Methylene chloride is also a
probable human carcinogen.
2. Many of the other solvents used in paint strippers are highly
or moderately toxic by inhalation, ingestion, and skin contact
and/or absorption. In addition to the hazards of specific
solvents, most solvents can also cause narcosis if inhaled
(dizziness, fatigue, loss of coordination, nausea). Many of
these solvents are also flammable.
3. Caustic soda used in some bleaches and for paint stripping is
highly corrosive by skin or eye contact, causing severe burns.
Similarly oxalic acid is corrosive. Concentrated hydrogen
peroxide used in some bleaches is moderately toxic by skin or eye
contact. Hypochlorite (chlorine-type) bleaches are moderately
toxic by skin contact or inhalation. Mixtures of chlorine
bleaches and ammonia are highly toxic by inhalation, possibly
being fatal.
4. Heat guns and torches can vaporize paint. There have been
many cases of lead poisoning from using torches, and even heat
guns, to remove lead-based paint.
Precautions
1. Dimethyl adipate paint strippers are safer than other solvent
types because of its high boiling point, which means little
evaporates.
2. Volatile, solvent-based paint strippers should preferably be
used outside, unless only small amounts of stripper are being
used. If used indoors, be sure to have good dilution ventilation
(e.g. window exhaust fan). In small areas, or if there is not
adequate ventilation, use a NIOSH-approved respirator with
organic vapor cartridges.
3. Do not smoke, have open flames or other sources of ignition
(e.g. pilot light) in the room if you are using flammable
solvents. Solvent-soaked rags should be placed in an approved,
self-closing waste disposal can which is emptied each day.
4. Wear gloves, goggles and a protective apron when handling
caustic soda (sodium hydroxide), oxalic acid bleaches, or
chlorine-type bleaches. An eyewash fountain and emergency shower
should be available.
5. Avoid using torches to remove paint. Do not use heat guns if
the paint contains lead.
PAINTING AND FINISHING
Wood can be painted with most types of paint, can be stained,
lacquered, or varnished, and can be oiled with linseed oil, tung
oil, or other types of oil. Other materials used in finishing
include shellacs, polyurethane coatings, and waxes. Some
woodworkers mix their own paints from dry pigments.
Hazards
1. Mixing paint from dry pigment can lead to possible inhalation
of the pigment powder or accidental ingestion. In particular,
lead chromate pigments are extremely toxic due to the risk of
lung cancer.
2. Solvent-based paints, waxes, polyurethane varnishes, and wood
stains commonly contain mineral spirits or turpentine, which are
moderately toxic by skin contact, inhalation and ingestion. Some
wood stains might also contain wood preservatives.
3. Water-based paints usually contain 5-10% solvents to help
dissolve the plastic resins. These solvents include ethylene
glycol, propylene glycol, and the more toxic glycol ethers.
Ethylene glycol is moderately toxic by ingestion, but the amount
present is small enough to make the risk negligible.
4. Shellac usually contains ethyl alcohol, which is slightly
toxic by skin contact and inhalation, and sometimes methyl
alcohol, which is moderately toxic by skin absorption and
inhalation. Lacquers can contain more toxic solvents such as
toluene, hexane, etc.
5. Most of the solvents used in varnishes, lacquers and shellacs
are flammable. Paints, waxes and polyurethane coatings based on
mineral spirits are combustible.
6. Tung oil, linseed oil, and most other oils have no significant
toxic hazards, although a few people might develop allergies to
them.
7. Oil-soaked rags and paper towels are a spontaneous combustion
hazard.
Precautions
1. Use ready-made paints rather than mixing your own. Do not
eat, drink or smoke in the area where painting is done.
2. Use water-based paints rather than solvent-based ones if
possible. Use latex paints containing ethylene glycol or
propylene glycol rather than glycol ethers.
3. Use shellacs containing denatured (ethyl) alcohol rather than
ones containing methyl alcohol. 4. Wear gloves and goggles when
painting or finishing.
5. Have dilution ventilation (e.g. window exhaust fan) or do the
finishing outside. If ventilation indoors is not adequate, wear
a NIOSH-approved respirator with organic vapor cartridges. 6.
Finishes should be sprayed inside an explosion-proof spray booth,
or wear a NIOSH-approved respirator with organic vapor cartridges
and dusts and mists filters. Touchup with spray cans could be
done outdoors. Brush on materials, whenever possible, to avoid
the hazards of spraying. 7. Avoid open flames, lit cigarettes and
other sources of ignition in the room when applying flammable
finishes, or when spraying.
8. Store oil-soaked rags and paper towels in oily waste cans
which are emptied daily. Dispose of as hazardous waste or
recycle by professional laundering. A few rags can be allowed to
dry on a clothesline and discarded in the trash.
References
1. Canadian Centre for Occupational Health and Safety. (1988).
Infograms on Hand Tools. 16 pp. CCOHS, Hamilton, Ontario, Canada.
2. Canadian Centre for Occupational Health and Safety. (1988).
Infograms on Powered Hand Tools. 11 pp. CCOHS, Hamilton, Ontario,
Canada.
3. Canadian Centre for Occupational Health and Safety. (1988).
Infograms on Woodworking Machines. 10 pp. CCOHS, Hamilton,
Ontario, Canada.
4. Fink, T. J. (1990). Chemical hazards of woodworking. Fine
Woodworking. Jan/Feb, pp. 58-63.
5. International Labor Office. (1983) Encyclopedia of
Occupational Safety and Health. 2 volumes. 3rd ed. Geneva,
Switzerland.
6. Lampe, K., McAnn, M. (1985). AMA Handbook of Poisonous and
Injurious Plants. American Medical Association, Chicago.
7. Poisondex, Micromedix Inc. 1990.
8. Wills, J.H. (1982) Nasal cancer in woodworkers: A review. J.
Occup. Med. 24(7), 526-530. 9. Woods, B., Calnan, C.D. (1976).
"Toxic Woods." Br. J. Dermat. 9513, 1-97.
For Further Information
Written and telephoned inquiries about hazards in the arts
will be answered by the Art Hazards Information Center of the
Center for Safety in the Arts. Send a stamped, self-addressed
envelope for a list of our many publications. Permission to
reprint this data sheet may be requested in writing from CSA.
Write: Center for Safety in the Arts, 5 Beekman St., Suite 820,
New York, NY 10038. Tel: (212) 227-6220. CSA is partially
supported with public funds from the the New York State Council
on the Arts, the NYC Department of Cultural Affairs, and the NYS
Department of Labor Occupational Safety and Health Training and
Education Program.
(c) Center for Safety in the Arts, 1995.
This data sheet was adapted from chapter 17 of Artist Beware.
Table 1. Toxic Woods - By Robert Woodcock, R.N., B.S.N., C.E.N.
REACTION SITE SOURCE INCIDENCE
I - irritant S - skin D - dust R - rare
S - sensitizer E - eyes W - wood C - common
C - nasopharyngeal R - resp. LB-leaves, U - unknown
cancer C - cardiac bark
P - pneumonitis, N - nausea,
alveolotis malaise
(hypersensitivity
pneumonia)
DT - direct toxin
WOOD REACTION SITE POTENCY SOURCE INCIDENCE
Bald Cypress S R + D R
Balsam Fir S E,S + LB C
Beech S,C E,S,R ++ LB,D C
Birch S R ++ W,D C
Black Locust I,N E,S +++ LB C
Blackwood S E,S ++ D,W C
Boxwood S E,S ++ D,W C
Cashew S E,S + D,W R
Cocobolo I,S E,S,R +++ D,W C
Dahoma I E,S ++ D,W C
Ebony I,S E,S ++ D,W C
Elm I E,S + D R
Goncalo Aves S E,S ++ D,W R
Greenheart S E,S +++ D,W C
(Surinam)
Hemlock C R ? D U
Iroko I,S,P E,S,R +++ D,W C
Mahogany S,P S,R + D U
(Swietenia)
Mansonia I,S E,S +++ D,W C
N + D
Maple S,P R +++ D C
(C. Corticale mold)
Mimosa N ? LB U
Myrtle S R ++ LB,D C
Oak S E,S ++ LB,D R
C ? D U
Obeche I,S E,S,R +++ D,W C
Oleander DT N,C ++++ D,W,LB C
Olivewood I,S E,S,R +++ D,W C
Opepe S R + D R
Padauk S E,S,N + D,W R
Pau Ferro S E,S + D,W R
Peroba Rosa I R,N ++ D,W U
Purpleheart N ++ D,W C
Quebracho I R,N ++ D,LB C
C ? D U
Redwood S,P R,E,S ++ D R
C ? D U
Rosewoods I,S R,E,S ++++ D,W C
Satinwood I R,E,S +++ D,W C
Sassafras S R + D R
DT N + D,W,LB R
C ? D U
Sequoia I R + D R
Snakewood I R ++ D,W R
Spruce S R + D,W R
Walnut, Black S E,S ++ D,S C
Wenge S R,E,S ++ D,W C
Willow S R,N + D,W,LB U
W. Red Cedar S R +++ D,LB C
Teak S,P E,S,R ++ D C
Yew I E,S ++ D C
DT N,C ++++ D,W C
Zebrawood S E,S ++ D,W R
References:
Woods Toxic to Man, author unknown
Woods, B., Calnan, C.D. "Toxic Woods." Br. Journal of
Dermatology. 9513, 1976, 1-97.
ILO Encyclopedia of Occupational Health and Safety, 1983.
Lampe, K., McAnn, M. AMA Handbook of Poisonous and Injurious
Plants, AMA, 1985.
Poisondex, Micromedix Inc. 1990.
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Woodworking
