1,4-Dioxane Occupational Exposures

1,4-Dioxane Occupational Exposures


Both inhalation and dermal contact are important routes of occupational exposure to 1,4-dioxane.[1] CAREX Canada estimates that approximately 3,000 Canadian are exposed to 1,4-dioxane in the workplace.


The industry with the largest number of workers exposed to 1,4-dioxane is pharmaceutical and medicine manufacturing, followed by professional, scientific, and technical services. The largest occupational groups exposed are chemical technologists and technicians followed by chemists and chemical plant machine operators.

A European occupational exposure assessment developed models for three exposure scenarios including producing 1,4-dioxane, formulating products that contain it, and end-use (either of dioxane itself or products containing it).[1] Dermal exposures were predicted to be highest during the use of dioxane-containing metal cleaning products (1.5 mg/cm2 skin/day). Estimates of inhalation exposure were highest during product formulation; for example adding 1,4-dioxane, and mixing and bagging the final product (typical concentration estimated at 40 mg/m3).

Prevalence Estimate

Results show that approximately 3,000 Canadians are exposed to 1,4-dioxane in their workplaces; 56% of these workers are male.

The largest exposed industry groups are pharmaceutical and medicine manufacturing, followed by professional, scientific and technical services, basic chemical manufacturing, and public administration. When exposure is examined by occupation, the largest exposed group is chemical technologists and technicians (1,200 workers exposed), followed by chemists (720 workers exposed), chemical plant operators (330 workers exposed) and labourers in chemical products processing and utilities (220 workers exposed).

The number of workers exposed to 1,4-dioxane decreased by approximately 660 workers from 2006 to 2016 (an 18% decrease). This was primarily driven by a decrease in the total number of workers in the pharmaceutical manufacturing industry.

Workers exposed to 1,4-dioxane by industry in 2016

Workers exposed to 1,4-dioxane by region in 2016

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

* = < 50 workers
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 1,4-dioxane were collected from several sources:

  1. The Canadian Workplace Exposure Database (CWED) contains over 300 measurements for 1,4-dioxane 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 1,4-dioxane 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 1,4-dioxane as inhalation and dermal contact at work to levels above those encountered in the general environment.

To determine the number of workers potentially exposed to 1,4-dioxane 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 1,4-dioxane.

  1. Occupations and industries at risk of possible exposure to 1,4-dioxane 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 1,4-dioxane.

1. European Chemicals Bureau. European Union Risk Assessment Report: 1,4-Dioxane (2002) (PDF)

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