Naphthalene Occupational Exposures

Naphthalene Occupational Exposures


Inhalation and dermal contact are the most important routes of occupational exposure to naphthalene.[1,2] CAREX Canada estimates that approximately 8,500 Canadians are exposed to naphthalene in their workplaces.


The largest industrial groups exposed are in alumina/aluminum production and processing, petroleum and coal products manufacturing, and wood preservation. Other industries that may be exposed to naphthalene include coal tar and coke industries, as well as construction industries (paving and roofing).[2]

The largest occupational groups exposed to naphthalene are petroleum gas and chemical process operators, followed by machine operators in mineral and metal processing, and labourers in mineral and metal processing. Other workers may be exposed while producing mothballs, grinding wheels, and working with petroleum products, especially jet fuels.[3,4]

Prevalence Estimate

Results show that approximately 8,500 Canadians are exposed to naphthalene at work; 90% of these workers are male. Industries with the highest number of exposed workers are alumina/aluminum production and processing (naphthalene emission from graphite electrodes), petroleum and coal products manufacturing (where pure naphthalene and coke are manufactured), and wood preservation (where naphthalene is vapourized from creosote).

When exposure is examined by occupation, important occupational groups exposed include petroleum, gas and chemical process operators (1,400 exposed), machine operators in mineral and metal processing (1,300 exposed), and labourers in mineral and metal processing (1,100 exposed).

Workers exposed to naphthalene by industry

Workers exposed to naphthalene by region

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 naphthalene were collected from several sources:

  1. The Canadian Workplace Exposure Database (CWED) contains approximately 200 measurements for naphthalene 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 naphthalene 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 naphthalene as inhalation exposure at work at levels exceeding those encountered in non-occupational settings, such as exposure due to inhaling urban air (i.e. from incomplete combustion) and/or indoor air (i.e. from mothballs). Naphthalene is a polycyclic aromatic hydrocarbon (PAH), but exposure here is intended to reflect industries and occupations where it occurs as an industrial product, rather than as a mixed product of incomplete combustion. Further information on PAHs can be found elsewhere on the CAREX Canada website.

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


1. International Agency for Research on Cancer (IARC). Monograph summary, Volume 82 (2002) (PDF)
2. Scientific Committee on Toxicity Ecotoxicity and The Environment (CSTEE). Opinion on the results of the Risk Assessment of Naphthalene Report Version (Human Health): Final Report (2001) (PDF)

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