An estimated 4,200 Canadians will be diagnosed with stomach cancer annually [1]. Some risk factors for stomach cancer include smoking, having a history of helicobactor pylori infection or Epstein-Barr virus, and diets high in pickled or salted foods [1]. There is emerging evidence for occupational risk factors and stomach cancer. Occupation has been suspected to contribute to risk of developing stomach cancer with exposure to “dusty” occupations, exposure to N-nitrosamines and asbestos [2,3]. There are a number of different groups in the ODSS that show increased risks for stomach cancer.
Possible occupational exposures
Overall, the construction industry demonstrated an increased risk of stomach cancer and some construction trades were associated with higher risks. Construction workers may be exposed to asbestos, when working in older buildings, welding fumes, wood dust, and silica dust which may increase the risk for stomach cancer [5,6].
People working in chemical manufacturing were observed to be at an increased risk for stomach cancer. Some studies also saw increased risk of stomach cancer among chemical workers with possible exposure to dyes or solvents [2,7].
Work with electric and electronic products could lead to exposure to polychlorinated biphenyls although there is no evidence relating these exposures to stomach cancer [8,9]. Electrical production work may also be associated with various metallic dusts which have been associated with increased risk of cancer [5,10]. Some suggest exposure to inorganic lead as a contributor to the increased risk of stomach cancer among electrical or electronics workers [11,12].
Increased risk of stomach cancer was seen across many wood-related industries and occupations in the ODSS. Workers in manufacturing and processing of wood products are exposed to wood dust, chemicals, and possibly asbestos which have been linked to increased risk of stomach cancer [13].
Metal processing occupations expose workers to mineral dusts and metal dusts and fumes, as well as Polycyclic aromatic hydrocarbons (PAHs).
Elevated risk of stomach cancer was seen in various food-related industries and occupations. Previous studies in the literature also saw similar results although the relationship is not fully understood [5,15]. Those working in food manufacturing and processing may be exposed to organic dusts, pesticides, preserving agents [16]. For some occupations in restaurants (i.e. waiters), increases may be related to lifestyle and dietary factors [10].
Several other industry and occupation groups showed elevated risks of stomach cancer. Previous literature suggests that those working in rubber have a higher risk of stomach cancer [ref]. Workers in the rubber industries are exposed to dusty environments, fumes, and N-nitrosamines [17]. Workers in rubber industries had 1.13 times the risk of stomach cancer compared to all other workers in the ODSS.
Janitors and cleaners are regularly exposed to chemicals in cleaning agents. They had 1.24 times the risk of stomach cancer compared to all other workers in the ODSS. Similarly, those working in laundering or dry-cleaning occupations had 1.11 times the risk of stomach cancer. They are exposed to organic solvents which may carcinogenic but have not been associated with stomach cancer [18].
Bus drivers (HR 1.46) and subway and street railway operating occupations (HR 3.39) showed elevated risks of stomach cancer. These workers may be exposed to diesel engine exhaust, however, this exposure has not been linked to risk of stomach cancer.
Figure 1. Risk of stomach cancer diagnosis among workers employed in each industry group relative to all others, Occupational Disease Surveillance System (ODSS), 1983-2016
The hazard ratio is an estimate of the average time to diagnosis among workers in each industry/occupation group divided by that in all others during the study period. Hazard ratios above 1.00 indicate a greater risk of disease in a given group compared to all others. Estimates are adjusted for birth year and sex. The width of the 95% Confidence Interval (CI) is based on the number of cases in each group (more cases narrows the interval).
Figure 2. Risk of stomach cancer diagnosis among workers employed in each occupation group relative to all others, Occupational Disease Surveillance System (ODSS), 1983-2016
