Formaldehyde Occupational Exposures

Formaldehyde Occupational Exposures

Overview

Inhalation is the main route of exposure for formaldehyde. However, lower levels of exposure may occur via dermal absorption or ingestion.[1] CAREX Canada estimates that approximately 152,000 Canadians are exposed to formaldehyde in their workplaces. Currently, the three most important sources of formaldehyde exposure include decomposition of formaldehyde-containing resins, emissions from solutions (e.g. embalming fluid), and combustion sources (e.g. vehicle exhaust).[2]

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Although exposure to formaldehyde has decreased over time, exposure still occurs in a wide variety of occupations and industries. The wood product manufacturing and hospital industries are among the largest exposed industrial groups in Canada. In terms of occupations, the largest groups of workers exposed to formaldehyde are furniture and fixture assemblers.

In wood panel manufacturing, formaldehyde is released when heating adhesives, which can expose press operating and maintenance workers.[3] In furniture manufacturing, formaldehyde is released when preparing and applying varnishes or paints (especially when applied with a spray gun), and drying. Therefore, painters, manual labourers working at dryers, and maintenance workers can also be exposed.[3]

Other occupations with acute exposure to formaldehyde include cooks, embalmers, pathology lab workers, wood, and pulp and paper processing workers. Health care professionals (nurses, dentists, and pharmacists) may also be exposed while using or cleaning up medical products and equipment.[4,5]

Workers involved in producing resins, man-made vitreous fibres, and plastic products are potentially exposed to formaldehyde. Levels are expected to be low, however, because of improved ventilation and the development of resins that release less formaldehyde.[4]

Prevalence Estimate

Results show that approximately 152,000 Canadians are occupationally exposed to formaldehyde; 66% of these workers are male. Wood product manufacturing workers are the largest industrial group exposed, where exposure occurs from the use of formaldehyde-containing resins and glues. More women than men are exposed to formaldehyde in hospitals, schools, and clothing manufacturing, while exposure for men is much more common in furniture manufacturing and related industries.

When examining formaldehyde exposure by occupation, the largest group of workers exposed is furniture and fixture assemblers (12,000 exposed). Other important occupational groups include cooks (exposed at a low level during the grilling of some foods), labourers in wood, pulp and paper processing, and machinists.

Workers exposed to formaldehyde by industry

Workers exposed to formaldehyde by region

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

* = < 50 workers

Level of exposure

In total, approximately 152,000 Canadians are exposed to formaldehyde in their workplaces. The majority of workers exposed to formaldehyde are in the low exposure category. A substantial number of formaldehyde-exposed workers are at risk for moderate exposure, and very few are at risk of high exposure.

Level of Exposure by Industry

Identifying industries with either 1) workers exposed to high levels of formaldehyde or 2) a larger number of workers exposed to formaldehyde 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 formaldehyde. These results highlight industries with the most number of workers, as well as industries with the highest levels of exposure. Data for those industries with at least 4,000 workers exposed is shown.

For example, in the wood products manufacturing industry (which is the largest industrial group exposed to formaldehyde), nearly all of the exposed workers are in the moderate and high exposure categories. However, in the transportation equipment sector, where workers are exposed via the use of formaldehyde-containing plastic, paints and glues in motor vehicle and parts manufacturing, almost all workers are in the lowest exposure category (97%). 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.

*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 formaldehyde were collected from several sources:

  1. The Canadian Workplace Exposure Database (CWED) contains over 10,500 measurements for formaldehyde 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 formaldehyde 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 formaldehyde as inhalation and/or dermal exposure at work, at levels exceeding those encountered in the general environment (excluding exposure to cigarette smokers).

To determine the number of workers potentially exposed to formaldehyde 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 formaldehyde.

  1. Occupations and industries at risk of possible exposure to formaldehyde 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 2006 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 formaldehyde.

Exposure Level Method

CAREX uses available workplace exposure measurements in the CWED to create exposure level categories by industry and occupation. For formaldehyde, 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 ppm (which is a threshold level for moderate exposure chosen by CAREX Canada for risk of nasopharyngeal cancer1).

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 1.0 ppm (which is a threshold level for high exposure chosen by CAREX Canada for risk of nasopharyngeal cancer1).

Category 3: High 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 1.0 ppm (which is a threshold level for high exposure chosen by CAREX Canada for risk of nasopharyngeal cancer1).
1. Hauptmann M, Lubin JH, Stewart PA, Hayes RB, Blair A. ‘Mortality from solid cancers among workers in formaldehyde industries.‘ Am. J Epidemiol. 2004 Jun 15;159(12):1117-30.
Sources

2. Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST). Prevention Guide: Formaldehyde in the Workplace (2006) (PDF)
3. Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST). Prevention Fact Sheet – Exposure to formaldehyde in the workplace: Wood furniture manufacturing (2006) (PDF)
4. National Toxicology Program (NTP). 14th Report on Carcinogens for Formaldehyde (2016) (PDF)
5. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Formaldehyde (1999) (PDF)

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