As woodworkers, we use wood to build beautiful furniture and other objects. But wood does have a dark side: it can be harmful to our health. Trees contain toxins in the bark, fruit, sap, wood, and foliage but for the majority of woodworkers, exposure to the wood and, in particular, wood dust is the primary health issue.
Exposure to wood dust has long been associated with a variety of adverse health effects. These include sneezing, wheezing, coughing, watering of the eyes, loss of smell, nose bleeds, skin rashes, asthma, decreased lung capacity, headaches, prolonged colds, chronic bronchitis, and even cancer. That’s why it is important to understand the health risks of wood dust and take preventative measures when working with wood to reduce your exposure to wood dust.
How Wood Dust Affects Us
Exposure to wood dust occurs primarily through skin contact and inhalation as you go about your sawing, sanding, routing, shaping, and other woodworking activities. The dust settles on sweaty skin and you breath it in as it floats around the woodshop. If the dust is thick enough, you can even ingest it through the mouth.
The severity and type of reaction to wood dust depends on a number of factors including the concentration of the dust, the duration of exposure, the type of wood, differences in individual’s susceptibility to specific allergens, and whether you have become sensitized over time. Coughing, sneezing and watering of the eyes are common reactions that most woodworkers have experienced at one time or another. These reactions are often a result of the dust physically irritating the sensitive mucous membranes of the eyes and nose.
Other reactions, including dermatitis (skin rashes) and asthma may be due to sensitivities to chemicals found in the wood. Some of these chemicals naturally occur in the wood, especially in the heartwood, and others are from biological contaminants such as bacteria, fungi, or moulds. Plicatic acid, for example, found naturally in western red cedar, has been shown to cause asthma reactions and other allergic effects. Another example is salicylic acid, found in large concentrations in willow and birch. This compound is similar to the active component of aspirin and individuals that are allergic to aspirin may react with only casual exposure to the wood.
With repeated exposures, one can become sensitized to the dust and develop more severe, complex reactions such as allergic dermatitis. Symptoms may include blisters, rashes, redness, scaling, and itching. Once you become sensitized, exposure to even small amounts of dust can trigger the reaction. In other words, a rash can break out without the dust even coming in physical contact with the affected region. The parts of the body most often affected are the hands, forearms, eyelids, face, neck, and (gulp) genitals. In many cases, rashes will form on the webbing between the fingers of the hand.
Wood Dust and Cancer Risks
Cancers have also been associated with wood dust exposure. The National Institute for Occupational Safety and Health (NIOSH) considers both hardwood and softwood dust to be potentially carcinogenic and provides guidance on specific wood dust exposure limits. The primary types of cancers associated with wood dust exposure are nasal and sinus cavity cancer, lung cancer, and Hodgkin’s disease. Not too surprisingly, those most at risk are workers in mills, furniture plants, cabinet makers, and carpenters. That is, people who spend a significant amount of time around wood and wood dust.
The association between occupational exposure to wood dust and various forms of cancer has been investigated in many studies and in many countries. This Toxicologic Review of Selected Chemicals page from the CDC summarizes some of the research. Note that in 1987, the International Agency for Research on Cancer (IARC) classified furniture manufacturing in Category I (confirmed human carcinogen) and carpentry in Category 2B (suspected human carcinogen).
Toxicity Varies by Wood Species
All woods should be considered potentially toxic but some woods are more toxic than others. For example, hypersensitivity reaction leading to asthma has been reported as a result of exposure to Western red cedar, Cedar of Lebanon, oak, mahogany, and redwood. Western red cedar is a particularly allergenic species that has achieved a certain measure of notoriety in the North American wood products industry. It has been estimated that at least five percent of forest industry workers in British Columbia exposed to Western red cedar dust are allergic to it.
Dermatitis caused by exposure to wood dusts is common, and as many as 300 species of trees – hardwoods and softwoods – have been implicated in wood-caused dermatitis. And it’s not just imports or exotic woods but domestic species as well. NIOSH considers both hard and soft wood dust to be potentially carcinogenic but there is some evidence to indicate a greater risk of certain types of cancer related to hardwood dust exposure. For example, NIOSH states that certain species of hardwood including oak, mahogany, beech, walnut, birch, elm, and ash have been reported to cause nasal cancer in woodworkers.
Here is a wood toxicity chart that shows how various woods compare to each other. If you look at the potency column, some of the woods that are particularly toxic include black locust, cocobolo, mansonia, oleander, rosewoods, and yew.
The good news is that there are ways to limit your exposure to wood dust while woodworking:
- Use a dust collection system to harvest the majority of wood chips and dust at the source. Sanders, shapers, and routers generally produce the greatest amount of dust so keep that in mind when you design a dust collection system.
- Use a dust filtration system to trap the small airborne particles that are always floating around in your shop. Consider a ceiling hung unit that can be mounted in an out of the way corner. These puppies go for a few hundred bucks.
- Do NOT use compressed air to clean work surfaces. Vacuum or gently sweep the dust instead.
- Use a dust mask. This is especially beneficial for sanding, routing, turning wood and other operations where you’re working in close proximity to where the dust and chips are being churned out.
- Wear goggles. The wrap-around kind are best as they keep out more of the insidious dust that is coming from all directions.
- Wear a long sleeve shirt if you find that dust frequently clings to your forearms. Just make sure the sleeves are not too baggy, posing a potential safety hazard in themselves. I’ve also heard of woodworkers putting a protective barrier cream on their arms and other exposed skin surfaces.
- Wear tight fitting gloves. Thin leather gloves protect you from splinters and any toxins in the wood. Latex gloves are another option, especially when working with oily woods or finishing materials.
- Wash your eyes after a woodworking session. Blow your nose too while you’re at it. When done for the day, take a shower and put your dust-laden clothes in the laundry basket. This will keep you from being repeatedly exposed to the wood dust.