Wood Dust

This page is long, but I truly believe it is worth the effort to read it if you are at all concerned with the health risks involved with wood dust. Please take the time too look at it.

The next time I looked there was response by a doctor sighting 6 references to studies all from peer reviewed journals, with summaries of the findings in the articles. Here they are:

Okwari OO et al. Lung function status of workers exposed to wood dust in timber markets in Calabar, Nigeria. Afr J Med Med Sci. 2005 Jun;34(2):141-5. Found that exposure to wood dust in timber market workers in Nigeria had poorer respiratory function, higher respiratory and nonrespiratory symptoms (skin and eye irritation) than control subjects. 421 people were tested in this study. Workers exposed to wood dust had restrictive pattern of ventilatory function impairment, and the degree of impairment correlated with how long the workers were working in the industry.

Meo SA. Lung function in Pakistani wood workers. Int J Environ Health Res. 2006 Jun;16(3):193-203. 46 non-smoking wood workers found to have significant reduction in lung function as measured by spirometry relative to their matched controls. This impairment was increased with the duration of exposure to wood industries. It is concluded that lung function in wood workers is impaired and stratification of results shows a dose-response effect of years of wood dust exposure on lung function.

Barcenas CH et al. Wood dust exposure and the association with lung cancer risk. Am J Ind Med. 2005 Apr;47(4):349-57. Exposure to wood dust in 1300 lung cancer patients gives an adjusted odds ratio for lung cancer risk for combined wood dust related occupations and industries of 3.15, and 1.60 for overall summary exposure compared to control subjects.

Jansson C et al. Occupational exposures and risk of esophageal and gastric cardia cancers among male Swedish construction workers. Cancer Causes Control. 2005 Aug;16(6):755-64. Exposure to wood dust among 260,000 Swedish construction workers showed an incidence rate ratio of 4.8 for risk of gastric cardia adenocarcinoma.

Malkin R et al. The characterization of airborne occupational safety and health hazards in selected small businesses; manufacturing wood pallets. Ind Health. 2006 Jan;44(1):58-63. Walk-through evaluations at four wood pallet manufacturing companies found total dust measures ranged from 0.86 to 1.67 mg/m3, compared to the American Conference of Governmental Industrial Hygienists (ACGIH) guideline for wood dust is 1.0 mg/m3.

Hursthouse A et al. A pilot study of personal exposure to respirable and inhalable dust during the sanding and sawing of medium density fibreboard (MDF) and soft wood. Int J Environ Health Res. 2004 Aug;14(4):323-6. The amount of respirable and inhalable dusts from sawing and sanding MDF and softwoods at the operator position in a typical cabinet-making workshop was measured. Exposure levels for the total inhalable fraction (<100 micron) were 6.9-91 mg/m3 for MDF and 2.5-45 mg/m3 for softwood. For the respirable fraction (< 10 micron) levels were 0.4-13 mg/m3 for MDF and 0.4-2.9 mg/m3 for softwood.

The ACGIH guideline for total dust exposure is 1.0 mg/m3 for an 8 hour period. Also, the dust that is thought to be the cause of respiratory problems and cancer risk is the inhalable fraction. This means that one sawing or sanding operation alone could expose a person to more fine dust alone than the amount of total dust he/she should be exposed to for an 8 hour shift.

From this data, one can conclude that exposure to wood dust in people working in the wood industry has measurable effects on your health. The fact that lung function damage from wood dust exposure worsens with time indicates that this effect has a dose-response relationship, (dose-response relationship: Relationship in which a change in the amount, intensity, or duration of exposure is associated with a change in risk of a specified outcome.) and therefore there is no real "safe" exposure level. Once you are exposed to wood dust, your lungs start to worsen. Similar conclusions can be made about cancer risk. Finally, the amount of dust we are exposed to is much higher than we think.

Now I would have thought that the above information would have been enough to satisfy the “nay” sayers, but it wasn’t. One complained that he didn’t have the time to decipher all of this information so the next post explained the links as follows:

He explained that in the first two studies cited above, it was found that decreased lung function worsened with the length of exposure (time spent working in the industry). This indicates that there is a dose-response relationship for wood dust exposure and loss of lung function. This means that there is no "safe" level of dust exposure -- once you start breathing it in, your lungs start to deteriorate.

To state that there is a "safe" level of dust exposure presupposes that there is a step-like relationship between dust exposure and disease -- that if you keep your exposure below some level, your health will be just fine, and you only have to worry once you go over that line. That's just not the case.

He further went on to explain that he was a pediatric oncologist, and there was an example that directly impacted his patients and hopefully that example would make this a little more clear. He went on to state there is a chemotherapy drug called daunorubicin that he used for some pediatric cancers. A side effect of daunorubicin can be weakening of the heart muscle so that your heart will not be able to pump as effectively as it used to, and this can lead to heart failure. There is a dose of daunorubicin that is considered "safe", but "safe" is not really an accurate term. He said that if he measure heart function in his patients as they got successive doses of daunorubicin, then he would be able to see a real decrease in the strength of their heart. Not so much that it would cause heart failure, but the difference would be there. He also knew that for some patients, they would go into heart failure after only one dose of daunorubicin.”

He then said that the question was whether or not his patients have heart disease from exposure to "safe" levels of daunorubicin. If you only define disease in terms of having heart failure or not, then no, these kids did not have disease. But as a group all of them would have a measurable decrease in heart function compared to kids that did not receive this drug. So from that standpoint, these patients have diseased hearts.

He then posed the question: Does it matter if his patients have decreased heart function, but not heart failure? He said it depends. These kids clearly have decreased reserve compared to normal kids. For a couch potato/Playstation playing kid, it probably won't matter. However, he had taken care of teenage athletes who told him that after their treatment was done, they couldn’t perform at the same level they used to. Maybe it's because their heart took a hit from daunorubicin, and this group of kids notice the difference because they put more stress on their heart. The thing he worried about was not what happens to these kids now, but 20-30 years from now, if it turns out that the damage done to their heart from daunorubicin gives them all heart failure in their 30's-40's.

He said that he continues to use daunorubicin because the alternative is not treating the cancer, in which case the kids will die. But this is an extreme example.

He then went back to wood dust and lung function. He said that wood dust exposure causes a measurable decrease in lung function that is related to the amount of exposure. Again, to suggest that there is a "safe" level presupposes that there is some level of dust that you can breathe in that causes no harm. This is not true. If you breathe in wood dust, measurable acute decreases in lung function can be demonstrated. If your definition of lung disease is limited to the presence or absence of pulmonary fibrosis, then one could say that one does not have lung disease. But like his cancer patients and their heart dysfunction due to daunorubicin, the bottom line is that your lungs can be affected by a single exposure to wood dust. And like his cancer patients, it might not matter now, but it may matter 20 years from now.

How much lung function can one give up and be fine? One of the parameters measured in the first two studies is something called forced vital capacity, or FEV1. In kids with asthma, the FEV1 goes down when they have an asthma attack. Kids with asthma are given a gizmo called a peak flow meter that measures how their FEV1 is doing. If they lose as little as 20%, then they are started on inhalers and nebulizers.

He pointed to the last two articles because they show that exposure to wood dust is probably a lot higher than we think.

Given this information, he said he was comfortable saying that wood dust exposure can cause lung disease and that given the dose-response behavior of this phenomenon that there is no "safe" dose. And from a lung function standpoint, he was also comfortable saying that all who work in a woodworking environment will have some measurable lung dysfunction.

He concluded by saying that it's just a matter of whether one is willing to take the risk or not and he for one was willing to take that risk, otherwise he wouldn't be in the process of setting up a workshop in his basement. But he was also giving a LOT of thought to his dust collection setup.
The link that contains the above information is: www.pubmed.gov. This is a searchable database of all biomedically related academic journals and contains the above studies.Specific recommendations As promised, that was long, but I truly believe it was worth reading. Now, if you’re concerned I know you are asking: What can I do to protect my health and the health of my family? To answer that, I will premise the following suggestions with: I am one person with one point of view. I am not a medical expert or a specialist in any field. Therefore, travel at your own risk. I give you the following suggestions based on my own years of woodworking experience. The wonderful thing about this country is that you are free to follow these suggestions or not. It’s your choice.

If you have a shop attached to your house, create a negative pressure in that shop. You don’t have to install a wind tunnel to accomplish this…..a bathroom exhaust fan will create a negative pressure. You don’t even have to move any air. If you have all doors and windows closed and you run that exhaust fan to the outside it will create a negative pressure in your shop. When you open the door it will prevent air from filtering into the rest of your house.
Either clean your close before you leave the shop or remove your outer close and leave them in the shop. If you take your dust laden shirt off in the kitchen and you shake it out …Nevermind… you get the idea.
Until such time as we have absolute answers about the dangers of wood dust and an affordable means of measuring levels of dust in your shop, wear a dust mask. No matter what dust collection system you choose, assume that there is dust in the air. I would rather that you wore a mask for 20 years that was not necessary than to hear that you bought a Clear Vue, thought you were safe and 20 years later you found out that you weren’t after you are hooked up to an oxygen bottle for the rest of your life.
Install a good dust collection system and when possible exhaust it outside. That has been Bill’s position for quite some time.
Clean your shop thoroughly and regularly. Put your dust mask on, use your leaf blower or the exhaust from a shop vac and blow the entire shop out. Use an exhaust fan with open doors and windows to change the air in your shop.