Dust and Toxic timbers

There are various forms of toxicity and harm caused by exposure to woods through dusts or by direct contact with the wood.

A few woods are toxic. All dust is toxic.

Dusty jobs, especially wood processing using high-speed machines, are associated with the enhanced incidence of nasal cancer. Immediate effects may be: skin irritation; rash; itching; blistering; eczema; sneezing; runny nose; rhinitis; sore throat; eye watering; inflamed eyelids; conjunctivitis; headaches; cramps; coughing; breathlessness; wheezing and asthma. This may not occur immediately but could have a latency period from 7 to 69 years. There can also be a variety of cancers of the respiratory, digestive, and urinary tracts as well as the blood and lymphatic systems, including Hodgkin’s disease. Wood dust has been classified as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer.

It is best to control dust at the source. Use wet sanding methods. Use a dust extractor. Filter/clean the air for the entire work area by installing appropriate powered circulating filters. Provide a suitable industrial vacuum cleaner to remove dust from work areas. Don’t use blowers, fans or compressed air to move wood dust.

As the dust produced while sanding in woodturning it is very difficult to catch at source, it is critical to wear an appropriate dust mask or respirator. This must remove particles of 1 to 5 microns. It must fit tightly to the face (beards conspire against this) or encase the head completely. Disposable nuisance masks do not do this. Dust respirators will give no protection at all against gases and vapours (eg from paint spraying). Use the correct fume mask for the product being used. After finishing work remove work clothing such as overalls carefully at the end of the task or shift to avoid generating dust clouds. Clubs should provide
washing facilities so dust is not taken home.

Wash face and hands immediately after finishing the task and before eating or drinking.

Other toxic materials in woodwork are: trichloroethane in some adhesives; isocyanates in 2-pot mixes; glycol ethers in stains and varnishes; and chromated copper arsenate in wood preservatives. As well as formaldehyde used in making resins such as urea-formaldehyde that are used in adhesives for some composite wood products (particle board, fiberboard, and plywood) and found in some paints, lacquers, and coatings used to manufacture wood furniture. It is also present in many household items we come into daily contact with.

You can develop allergies following contact by touch or through the inhalation of dust. In other words, both large and small particles can sensitise you to the allergen. The reaction can be a skin or lung reaction. Skin reactions are generally itchy rashes. Lung reactions are generally chronic coughs or wheezing.

Other types of problems come from chronic exposure to dusts that are small enough to reach the small airways and alveoli (the tiny sacs deep in the lung tissue were oxygen in the air gets transferred to the blood). Dusts larger than 10 microns settle out in the upper airways (nasal cavities and back of the throat). Between 0.1 and 10 microns they reach the small airways
(branching of the main windpipes into the lung tissue) and some of them stay.

The risk isn’t just cancer, but also scarring, inflammation and other damage, that eventually causes stiffening of the lungs so that the work of breathing increases. It’s not quite the same as your typical smokers’ emphysema, but it’s similar enough, and less responsive to treatment (eg. Anti-inflamatories and bronchodilators).

Of course, woodworkers and boatbuilders can develop problems due to exposure to other materials such as epoxies and silicates. Glass, being basically silica, and colloidal silica, both could cause silicosis. Epoxies, particularly the hardeners, are well known as allergy sensitisers.

In books, refereed papers, and on websites, more than 100 tree species are listed as having some toxic effect on persons who use the wood. Unfortunately, many lists use common names which may refer to many different species, eg “blackwood” which is a common name for vastly differing genera on most continents.

The list below brings together information on woods which New Zealand woodturners may work. As we gather a large variety of woods from garden-grown trees, this list can not be a complete reference. Some references which woodturners can use to check on other timbers is given after the table.