GENERAL


Woodworkers need to take precautions against dust when working with any lumber, whether the wood is domestic or exotic.   Wood dust is no good for your lungs or eyes, and some wood dust can also react with your body.  Possible reactions include skin rashes, watery eyes, respiratory problems, headaches, dizziness, or nausea.  The degree and type of reaction depends on an individual’s susceptibility to certain allergies, as well as the concentration of dust and the amount of time exposed to dust.  The same reactions from person to person are not always a certainty. In general, toxicity is in one of three categories: irritation, sensitization, and poisoning.


Irritation


Skin, respiratory tracts, and mucous membranes get irritated easily by any fine dust because dust absorbs moisture, thereby drying out the surface with which the dust is in contact.  Itchy skin and sneezing are examples of basic irritation thanks to wood dust.  The level of irritation is proportional to the exposure time to, and concentration of, wood dust. But irritation is not necessarily benign.  Woods like walnut and rosewood emit pleasant odors with low levels of dust, which most woodworkers equate with being one of the benefits of working with woods.  However, the natural substances in these woods that cause the scents are also potentially toxic with greater dosage exposure and concentration.  Long term effects of exposure to wood dust can include developing an allergic reaction to the dust or possibly nasal cancer.


Sensitization


Substances in wood that cause an emerging (and potentially serious) allergic reaction after repeated exposure are called sensitizers.  This type of toxicity is specific to individuals and takes time to develop some people may experience a significant reaction to a wood while others do not.  While sensitization typically takes time and repeated exposure to develop, it is possible for some individuals to have an allergic reaction to a wood upon their first contact. 

Even if you do not have any reaction to a wood (or its dust) the first few times you use it, it’s still vital that you take precautions and avoid as much exposure as possible.  It’s possible that your body will develop a reaction the more you are exposed.


Poisoning


Universally lethal chemicals are rarely found in natural wood that’s available on the commercial market.  Most poisons in plants and trees are located in the bark and/or sap there are some exceptions for rare woods. 

Sometimes poisonous chemicals are introduced to wood products, such as with pressure treated lumber.  Hardwoods cut for cabinetry, flooring, and furniture are not pressure treated. Some common woods demand that woodworkers be aware of their own allergies.  Those who have an allergic reaction to aspirin should avoid using woods from birch and willow trees (Betula spp. and Salix spp.) because these contain good concentrations of salicylic acid, the key ingredient in aspirin.  See A Guide to Useful Woods of the World Appendix B for more. 


Prevention


You should limit your exposure to wood dust by doing the following things.


1.    Use vacuum dust collection in your shop, and keep your shop ventilated with fresh air.  

2.    Use protective equipment while woodworking: dust mask, goggles or a full-face respirator, and a protective barrier cream on your arms or exposed skin. 

3.    Immediately after woodworking change your clothes, wash them, and take a shower.  This will prevent transferring wood dust to your house where you or your family may be repeatedly exposed to it.  


What about toxicity of wood in my finished project?


Baby cribs and food utensils are popular projects, and ones that woodworkers are often curious about ”safe“ woods and finishes.   The short: a sealed and finished wood poses no toxic risk. 


What about the sealer or finish then?  Solvent-based finishing products (lacquer, varnish, etc) are highly toxic in their liquid state, but cured lacquer and varnish finishes are perfectly safe. 


For projects that come in contact with food, such as salad bowls and cutting boards, you really don’t want a hard shell finish (lacquer or varnish) that can chip or rub off.  Mineral oil, teak oil, and butcher block oil are all popular and safe choices for these projects.


A popular finish for baby cribs is shellac, as the FDA approves this for use in the capsules of medications.  This approval makes many woodworkers feel that shellac is more safe than other finishes.  But cured lacquer is safe, as is any cured solvent- or water-borne finish.

  

Wood/Dust Toxicity

Edited by: Bruce Campbell


For centuries, it's been fairly common knowledge that some woods could hinder your health. As far back as 60 A.D., the Roman historian and naturalist Pliny the Elder described a case where four soldiers actually died after drinking wine from hip flasks made of yew. Of lesser gravity was the experience of a few German sawyers in the early 1700s. It seems they developed chronic irritation of the nose and eyes, as well as headaches, from sawing bald cypress.


What are your chances of a reaction to wood? Statistics say that only 2 to 5% of all people develop an allergic sensitivity to one or more compounds found in wood. But, if you handle a lot of potentially toxic species, and work with them long enough, you increase your chances of an allergic reaction. And, with sufficient exposure, some woods bother almost everyone.


Any dust, including wood dust, mildly irritates the sensitive mucous membranes of your nose and eyes, making you sneeze and tear. The dust of some woods such as western red cedar and rosewood can be especially bothersome. However, other woods, called irritants, can make you even more uncomfortable, with a rash that classifies as either irritant dermatitis or allergic dermatitis. The rash usually has a uniformly red, swollen area that may erupt in blisters, and typically first shows up on the webs of skin between your fingers. Irritant woods include black locust, cocobolo, ebony, oleander, satinwood, sequoia, and yew.


However, for you to get an allergic-type rash, you first must be allergy-prone to one of more of the chemicals found in certain woods called sensitizers. And, it may take repeated contact for your body to develop a great enough allergy for it to react (the so-called "latency period of as little as five days and up to 6-8 months). If you do eventually get a reaction, the rash will look like poison ivy - red with small, individual, itchy bumps. Sensitizer woods include cypress, balsam fir, beech, birch, elm, greenheart, mahogany, maple, myrtle, redwood, sassafras, spruce, walnut, willow, western red cedar, and teak.


In addition to the actual wood dust, molds frequently trigger reactions, too. One that actually grows in wood happens to be extremely potent: Cryptostroma corticale. This mold lives happily between the bark and sapwood of many hardwood trees, especially favoring maple and birch. It's responsible for the marbleized spalting that woodturners prize, and for "maple bark stripper's disease," a condition with all the symptoms of a severe respiratory allergy.

If you have an aspirin allergy, be wary of willow and birch. Both of these species possess significant concentrations of salicylic acid (the predecessor of aspirin) and very sensitive individuals might only need casual exposure, such as a whiff of sawdust, to react.


Never say "no" to a dust mask. Among woodworkers, the chances of developing nasal and sinus cancer run about 5-40 times greater than non-woodworkers. Although researchers haven't identified the exact cancer-causing compound (primarily because the disease has a latency period from 30 to 50 years), some evidence points to dust from wood with high tannin content, such as chestnut, oak, redwood, western red cedar, and hemlock.


If you are sensitive to wood dust, work in a well ventilated area (this also reduces the risk to mold), avoid unseasoned wood as much as possible, and wash or shower frequently. If you develop persistent rashes or respiratory problems, contact your physician or dermatologist. (source of above: http://www.city-net.com/albertfp/toxic.htm)

There is an interesting list of Internet sites at http://www.davidillig.com/awg/safety.html where you can find additional information.


The chart below is a blend of information from two sources. The first is an article which appeared in American Woodturner in June 1990 (originally posted to rec.woodworking by Bruce Taylor. I took it from the Ohio Valley Woodturners Guild http://w3.one.net/~ovwg/Tips-Toxicty.html). The second is an article prepared by Roy Banner, a woodturner from Torrance, California who almost lost his life in 1989 to anaphylactic shock after turning pieces of exotic wood (see http://www.mimf.com/archives/toxic.htm ). Roy has assembled his data over the years from various sources. I can't judge with any authority the validity of the information and it's up to the you to further research any wood yourself. Take this as a jumping off point. You might also want to check out The Botanical Dermatology Database at http://bodd.cf.ac.uk/BoDDHomePage.html although I found it pretty hard to follow, technically.


A final note; this data does not take into consideration the added effect of formaldehyde in plywood, treated woods, sodium compounds in white pine to prevent blue stain, etc. Also, I am not aware of any work to study the interactions of woods and chemicals such as oils, glues, stains, etc. Bottom line - ensure good ventilation and good respiratory protection when you work in the shop.


Wood Toxicity Chart



Index of Meanings



[1] Cancer of nose and sinus: Statistics show that woodworkers have a 40 per cent greater chance of nasal cancer than the general population. However, the majority of statistics on nasal cancer are based on data from 1920-1960 when the furniture industry became highly mechanized with little or no dust control methods.


[2] Irritant or Sensitizer: Woods are either an irritant which cause a reaction fairly rapidly after exposure and will cause a similar reaction repeatedly, or sensitizers which may have a latency period of hours or months and may require repeated handling before reaction occurs. Sensitizer's are the more severe, because once you're sensitized, you're sensitized for life and the reactions only get more dramatic.


[3] Potency: This is the potential of the wood or sawdust doing harm and would vary with the individual. i.e., those who are allergy prone might think twice about working with wood classed as extremely potent.


[4] Risk: This is a qualitative assessment of the risk of a given wood doing serious harm. It is derived by combining the Potency and Incidence measures as follows:



Chart References:

1. _Woods Toxic to Man_, author unknown

2. Woods, B., Calnan, C.D., "Toxic Woods." _Br. Journal of Dermatology_ 1976

3. _ILO Encyclopedia of Occupational Health and Safety_ 1983

4. Lame, K., McAnn, MEDIUM., _AMA Handbook of Poisonous and Injurious Plants_, AMA 1985

5. _Poisondex_, Micromedix Inc. 1990

6. List of woods and toxicity characteristics, Roy Banner, 1989


___________________________________________________________________________________________________



Type

Reaction

Site

Potency

Source

Incidence

Bald Cypress

Sensitizer

Respiratory

+

Dust

Rare

Balsam Fir

Sensitizer

Eyes, skin

+

Leaves, bark

Common

Beech

Sensitizer, nasopharyngeal cancer

Eyes, skin, respiratory

++

Leaves, bark; dust

Common

Birch

Sensitizer

Respiratory

++

Wood, dust

Common

Black Locust

Irritant, nausea

Eyes, skin

+++

Leaves, bark

Common

Blackwood

Sensitizer

Eyes, skin

++

Dust, wood

Common

Boxwood

Sensitizer

Eyes, skin

++

Dust, wood

Common

Cashew

Sensitizer

Eyes, skin

+

Dust, wood

Rare

Cocobolo

Irritant, sensitizer

Eyes, skin, respiratory

+++

Dust, wood

Common

Dahoma

Irritant

Eyes, skin

++

Dust, wood

Common

Ebony

Irritant, sensitizer

Eyes, skin

++

Dust, wood

Common

Elm

Irritant

Eyes, skin

+

Dust

Rare

Goncalo aves

Sensitizer

Eyes, skin

++

Dust, wood

Rare

Greenheart (Surinam)

Sensitizer

Eyes, skin

+++

Dust, wood

Common

Hemlock

Nasopharyngeal cancer

Respiratory

?

Dust

Unknown

Iroko

Irritant, sensitizer, pneumonia

Eyes, skin, respiratory

+++

Dust, wood

Common

Mahogany (Swietenia)

Sensitizer, pneumonia

Skin, respiratory

+

Dust

Unknown

Mansonia

Irritant, sensitizer, nausea

Eyes, skin

+++

Dust, wood

Common

Maple (C. Corticale mold)

Sensitizer, pneumonia

Respiratory

+++

Dust

Common

Mimosa

Nausea


?

Leaves, bark

Unknown

Myrtle

Sensitizer

Respiratory

++

Leaves, bark; dust

Common

Oak

Sensitizer, nasopharyngeal cancer

Eyes, skin

++, ?

Leaves, bark; dust

Rare, unknown

Obeche

Irritant, sensitizer

Eyes, skin, respiratory

+++

Dust, wood

Common

Oleander

Direct toxin, nausea

Cardiac

++++

Dust, wood, leaves, bark

Common

Olivewood

Irritant, sensitizer

Eyes, skin, respiratory

+++

Dust, wood

Common

Opepe

Sensitizer

Respiratory

+

Dust

Rare

Padauk

Sensitizer, nausea

Eyes, skin

+

Dust, wood

Rare

Pau ferro

Sensitizer

Eyes, skin

+

Dust, wood

Rare

Peroba rosa

Irritant, nausea

Respiratory

++

Dust, wood

Unknown

Purpleheart

Nausea


++

Dust, wood

Common

Quebracho

Irritant, nasopharyngeal cancer, nausea

Respiratory

++, ?

Dust, leaves, bark

Common, unknown

Redwood

Sensitizer, nasopharyngeal cancer, pneumonia

Skin, eyes, respiratory

++, ?

Dust

Rare, unknown

Rosewoods

Irritant, sensitizer

Skin, eyes, respiratory

++++

Dust, wood

Common

Satinwood

Irritant

Skin, eyes, respiratory

+++

Dust, wood

Common

Sassafras

Sensitizer, nasopharyngeal cancer, direct toxin, nausea

Respiratory

+, ?

Dust, wood, leaves, bark

Rare, unknown

Sequoia

Irritant

Respiratory

+

Dust

Rare

Snakewood

Irritant

Respiratory

++

Dust, wood

Rare

Spruce

Sensitizer

Respiratory

+

Dust, wood

Rare

Walnut, Black

Sensitizer

Skin, eyes

++

Dust

Common

Wenge

Sensitizer

Skin, eyes, respiratory

++

Dust, wood

Common

Western red cedar

Sensitizer

Respiratory

+++

Dust, leaves, bark

Common

Willow

Sensitizer, nausea

Respiratory

+

Dust, wood, leaves, bark

Unknown

Teak

Sensitizer, pneumonia

Skin, eyes, respiratory

++

Dust

Common

Yew

Irritant, direct toxin, nausea

Skin, eyes, cardiac

++,++++

Dust, wood

Common

Zebrawood

Sensitizer

Skin, eyes

++

Dust, wood

Rare