Wood Dust Occupational Exposures

Wood Dust Occupational Exposures

Overview

Inhalation is the most important route of exposure, however dermal contact may also lead to skin-related health outcomes, such as dermatitis.[1,2]

CAREX Canada estimates that approximately 304,000 Canadians are exposed to wood dust in their workplaces. The largest industrial groups exposed include residential building construction, building finishing contractors, furniture and kitchen cabinet manufacturing, and sawmill and wood preservation.

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The largest occupational group exposed to wood dust are carpenters. Other important occupations likely exposed are cabinetmakers, carpentry trades contractors and supervisors, and labourers in wood, pulp, and paper processing.

Potential for exposure to wood dust can also occur in window and door manufacturing, joinery shops, wooden boat manufacture, installation and refinishing of wood floors, pattern and model making, and logging.[3]

Wood dust exposures have decreased significantly over the past few decades. Furniture and cabinetry shops are generally thought to have the highest exposures, particularly during sanding and finishing work, when the finest particles are generated.[3,4] Higher exposures have been measured in plywood and particleboard mills, where wood is sawn and sanded, and near chippers, saws, and planers in sawmills and planer mills.[3]

A study in a British Columbia lumber mill also found high exposures during tasks such as sawdust clean-up, planing kiln-dried lumber, and driving mobile equipment in the yard.[5]

Prevalence Estimate

Results show that approximately 304,000 Canadians are occupationally exposed to wood dust; 94% of these workers are male. The largest industrial group exposed to wood dust is the construction sector, including residential building construction and building finishing contractors. Approximately 183,000 Canadian workers are exposed in this sector. A larger proportion of the working population in British Columbia are exposed to wood dust due to a large and diverse logging and wood production industry. While British Columbia has only 13% of the working population in Canada, nearly 20% of wood dust exposed workers are in British Columbia.

When examining exposure by occupation, the largest exposed group is carpenters (166,000 workers exposed). Other common occupations at risk of exposure to wood dust include cabinetmakers (19,000 workers exposed), carpentry trades contractors and supervisors (16,000 workers exposed), and labourers in wood, pulp, and paper processing (15,000 workers exposed).

The number of workers exposed to wood dust decreased by approximately 34,000 workers from 2006 to 2016 (a 10% decrease). This was driven by a decrease in the total number of loggers, sawmills, related operators, cabinentmakers, and carpenters.

Workers exposed to wood dust by industry in 2016

Workers exposed to wood dust by region in 2016

Click the second tab to view total number of workers exposed.

Level of Exposure

In total, approximately 304,000 Canadians are exposed to wood dust in their workplaces. The majority of workers exposed to wood dust are in the moderate exposure category. A significant number of wood-dust exposed workers are at risk for high exposure.

Workers exposed to wood dust by exposure level in 2016

Level of exposure by industry

Identifying industries with either 1) workers exposed to high levels of wood dust or 2) a larger number of workers exposed to wood dust is important in guiding cancer prevention efforts to prioritize exposed groups and target resources most effectively.

The table below shows the number of workers exposed by industry group and level of exposure to wood dust. These results highlight industries with the most number of workers, as well as industries with the highest levels of exposure. For example, in wood-based industries, such as wood product manufacturing and furniture manufacturing, the majority of exposed workers fall into the highest exposure category. However, in building construction, the largest industrial group, the majority of exposed workers are in the moderate exposure category. Depending on the goals of a prevention campaign, exposure reduction in the large industrial group might be a useful strategy, or reducing exposure to those at highest risk of exposure could be seen as a priority.

Workers exposed to wood dust by exposure level and industry in 2016

*Numbers may not add up due to rounding
Methods and Data

Our Occupational Approach page outlines the general approach used to calculate prevalence and exposure level estimates for workplace exposures.

Data Sources

Data used in developing the occupational estimates for wood dust were collected from several sources:

  1. The Canadian Workplace Exposure Database (CWED) contains over 9,600 measurements for wood dust exposure. These measurements were collected during the years 1981 to 2004 in Ontario and British Columbia workplaces.
  2. Canadian and US scientific peer reviewed publications that addressed wood dust exposure in Canada and the United States.
  3. Grey literature including technical reports from governments and international bodies.

Prevalence Estimate Method

CAREX defines exposure to wood dust as inhalation exposure above levels expected in the general environment (exceptions may be those who often pursue hobby carpentry at home).

To determine the number of workers potentially exposed to wood dust at work, CAREX occupational exposure experts used methods previously established in other peer-reviewed CAREX projects in Europe. A series of steps were taken to assign exposure proportions to occupations and industries at risk of exposure to wood dust.

  1. Occupations and industries at risk of possible exposure to wood dust were identified using any combination of data sources described above.
  2. The total number of workers in each identified occupation and industry intersection was obtained from Statistics Canada 2016 census data.
  3. A percentage of workers exposed was assigned to that occupation and industry intersection. Percentages were determined by consultation with existing evidence in the data sources, previously established methods from the Europe CAREX estimates and the expert judgement of CAREX occupational hygienists.
  4. The number of workers in the identified group is multiplied by the assigned percentage to calculate the prevalence estimate of workers exposed to wood dust.

Exposure Level Method

CAREX uses available workplace exposure measurements in the CWED to create exposure level categories by industry and occupation. For wood dust, these categories are:

Category 1: Low Exposure

A group of workers (people in the same job category and industry) is put in this exposure category for one of two reasons:

  1. The are no valid measurements, but a hygienist identified this group as typically exposed during literature and other reviews;
  2. There are valid exposure measurements in the CWED and a hygienist review determined that exposure is plausible; AND EITHER:
    1. There are less than 10 samples available in the CWED, OR
    2. There are ≥10 measurements available but they do not meet the criteria for Moderate Exposure.

Category 2: Moderate Exposure

A group of workers is put in this exposure category if:

  1. There are at least 25 individual samples in the CWED, AND
  2. 20% or more samples have a value higher than 0.5 mg/m3 (which is ½ of the current occupational exposure limit for wood dust).

OR

  1. There are at least 10, but less than 25, individual samples in the CWED, AND
  2. 20% or more samples have a value higher than 2.5 mg/m3 (which is ½ of the historic occupational exposure limit for wood dust).

Category 3: High Exposure

A group of workers is put in this exposure category if both these criteria are met:

  1. There are at least 25 individual samples in the CWED, AND
  2. 20% or more samples have a value higher than 2.5 mg/m3 (which is ½ of the historic occupational exposure limit for wood dust).

Changes over time: 2006 vs. 2016

Many of the changes observed in the 2016 estimates reflect the changes in the Canadian labour force. If the number of workers in an industry and/or occupation increases or decreases, the number of workers exposed to a substance found in that industry and/or occupation will also change.

From 2006 to 2016, the overall number of workers in the labour force increased by approximately 8%, or 1.4 million workers. The industries with the largest increase in number of workers include health care and social assistance (422,000 workers, +25%), construction (296,000, +28%), and professional, scientific, and technical services (213,000 workers, +19%). Management of companies saw the largest percent increase, with 40% (8,300) more workers. The industries with the largest decrease in number of workers in the labour force include manufacturing (-409,000 workers, -20%) and agriculture (-79,000 workers, -15%). 

 

Changes in the number of workers in the Canadian labour force from 2006 to 2016 by industry and NAICS code

Sources

1. National Toxicology Program. 14th Report on Carcinogens for Wood Dust (2016) (PDF)
3. International Agency for Research on Cancer (IARC). Monograph summary, Volume 62 (1995) (PDF)
4. Canadian Centre for Occupational Health and Safety (CCOHS). Health and Safety Report, Volume 2, Issue 10: Wood Dust More Harmful Than Once Believed (2004)
5. Teschke K, Demers PA, Davies HW, Kennedy SM, Marion SA and Leung V. “Determinants of Exposure to Inhalable Particulate, Wood Dust, Resin Acids, and Monoterpenes in a Lumber Mill Environment.” Ann Occup Hyg 1999;43(4):247-255.

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