Lead Occupational Exposures

Lead Occupational Exposures

Overview

Inhalation is the most common route of occupational exposure, followed by ingestion.[1] CAREX Canada estimates that approximately 277,000 Canadians are exposed to lead in their workplaces.

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The largest industrial groups exposed include public administration (e.g. police officers), followed by building equipment contractors, and automotive repair and maintenance. In terms of occupation, the two largest exposed groups are welders, followed by police officers. Other large occupational groups that are at higher risk to lead exposure include auto mechanics, plumbers, and pipefitters.

Additional occupations that are exposed include workers involved in mining, lead smelting and refining industries, battery production or recycling, steel welding or cutting operations, construction, rubber products and plastics industries, printing industries, and firing ranges.[2]

Prevalence Estimate

Results show that approximately 277,000 Canadians are occupationally exposed to lead; 90% of these workers are male. The largest industrial group of lead-exposed workers is public administration, which includes police officers who are exposed to lead via their use of ammunition.

When examining exposure by occupation, the largest groups exposed include welders (77,000 exposed) along with police officers (34,000 exposed). Other large occupational groups (especially for men) are auto mechanics, plumbers and pipefitters. For women, while the largest exposed groups are police officers (6,900 exposed) and vocational instructors (4,200 exposed), other important occupations include welders and electronics assemblers.

Workers exposed to lead by industry

Workers exposed to lead by region

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

* = < 50 workers

Level of exposure

In total, approximately 277,000 Canadians are exposed to lead and inorganic lead compounds in their workplaces. The majority of workers exposed to lead are in the low exposure category. A substantial number of lead-exposed workers are at risk for moderate or high exposure.

Level of Exposure by Industry

Identifying industries with either 1) workers exposed to high levels of lead and lead compounds or 2) a larger number of workers exposed to lead 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 lead. 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 construction industries (236, 237 and 238 below), nearly all of the exposed workers are in the low and moderate categories. However, in repair and maintenance (where workers are mainly exposed from welding and soldering), many (approximately half) of the workers are in the high category of exposure. 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 lead were collected from several sources:

  1. The Canadian Workplace Exposure Database (CWED) contains over 10,500 measurements for lead 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 lead 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 lead as inhalation exposure at work above average levels expected in the general environment (including food sources).

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

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

Exposure Level Method

CAREX uses available workplace exposure measurements in the CWED to create exposure level categories by industry and occupation. For lead and inorganic lead 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 0.025 mg/m3 (which is half the current occupational exposure limit for lead).

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 0.05 mg/m3 (which is the current occupational exposure limit for lead).

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 0.05 mg/m3 (which is the current occupational exposure limit for lead).
Sources

1. National Toxicology Program (NTP). 14th report on carcinogens for Lead and Lead Compounds (2016) (PDF)
2. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile: Lead (2005) (PDF)

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