The largest occupational groups exposed to nickel are welders (working with stainless steel), followed by construction millwrights and industrial mechanics, and machining tool operators, and automotive service technicians and mechanics. Occupations that involve producing nickel alloy and stainless steel, welding, electroplating, grinding, and cutting operations may be exposed as well.[2]

According to the Burden of Occupational Cancer in Canada project, occupational exposure to nickel leads to approximately 170 lung cancers each year in Canada, based on past exposures (1961-2001).[3,4] This amounts to 0.7% of lung cancer cases diagnosed annually, and does not include the burden of lung cancer due to nickel exposure during welding, which is captured in the welding fumes estimate. Most occupational lung cancers associated with nickel exposure occur among workers in the manufacturing sector. These cancers also occur among workers in mining, oil, and gas extraction sector.[4]

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 nickel were collected from several sources:

1. The Canadian Workplace Exposure Database (CWED) contains approximately 4,800 measurements for nickel 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 nickel 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 nickel and its compounds (i.e. metallic nickel, nickel oxide, nickel sulphide, nickel sulphate, nickel chloride) as inhalation exposure at work to nickel containing-dusts and/or fumes at levels exceeding non-occupational exposure. Dermal exposure was not considered as exposed (i.e. handling of coins).

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

1. Occupations and industries at risk of possible exposure to nickel 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 nickel.

Exposure Level Method

CAREX uses available workplace exposure measurements in the CWED to create exposure level categories by industry and occupation. For nickel and its compounds, 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 0.1 mg/m³ (which is the current occupational exposure limit for soluble nickel compounds).

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 0.2 mg/m³(which is the current occupational exposure limit for insoluble nickel compounds).

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 0.2 mg/m³ (which is the current occupational exposure limit for insoluble nickel compounds).