There are many occupational and environmental exposures that increase the risk of bladder cancer. They include many dyes and dye precursors, exposure circumstances, industrial chemicals, and other agents.
Note that this page includes information on occupational and environmental exposures classified as Group 1 or Group 2A by the International Agency for Research on Cancer (IARC), with sufficient or limited evidence for bladder cancer. For more information on how IARC classifies carcinogens, read this fact sheet.
A number of aromatic amine dyes and dye precursors strongly increase the risk of bladder cancer among exposed workers. They include 4-aminobiphenyl, benzidine, ortho-toluidine, and 2-naphthylamine.1 4-Aminobiphenyl, ortho-toluidine, and 2-naphthylamine are also present as contaminants in cigarette smoke. Occupational exposures during auramine production and magenta production also cause bladder cancer, although the increased risk could not be linked to auramine or magenta specifically due to the presence of other bladder carcinogens during the production of both dyes.1
There is also limited evidence that exposure to 4-chloro-ortho-toluidine, previously used in dye production and present as a contaminant and metabolite of the insecticide chlordimeform, may increase the risk of bladder cancer.2
Most of the dyes and dye precursors on this list are no longer used in Canada due to health concerns. The exception is ortho-toluidine, which may still be used to make the herbicides metolachlor and acetochlor, and rubber-vulcanizing chemicals. However, the number of Canadian workers who may be exposed is not known.
Occupational exposures during aluminum production, as a painter, and in the rubber production industry all cause an increased risk of bladder cancer.1 In all three of these exposure circumstances, workers may be exposed to multiple carcinogenic agents and the specific exposure(s) responsible for increased risk of bladder cancer were not identified. A number of the aromatic amines listed above have been used as pigments in paints, and as compounding agents in rubber manufacturing.
There is limited evidence that occupational exposure as a hairdresser or barber may increase the risk of bladder cancer.2 Hairdressers and barbers can be exposed to a number of chemicals when dyeing, bleaching, or perming hair.
Coal-tar pitch is used in roofing, paving, and electrode manufacture. There is limited evidence that exposure to coal-tar pitch may increase the risk of bladder cancer.1 CAREX Canada estimates that approximately 7,600 Canadians are exposed to coal-tar pitch at work. The occupations with the largest number of exposed workers include roofers and shinglers, construction trades helpers and labourers, machine operators in mineral and metal processing, and heavy equipment operators.3
There is also limited evidence that exposure to tetrachloroethylene (a chlorinated solvent) may increase the risk of bladder cancer.4 Approximately 15,000 Canadian workers are exposed to tetrachloroethylene on the job.5 Major occupational groups include printing press operators (where tetrachloroethylene is used in printing inks), dry-cleaning workers, labourers in textile processing, and chemical technologists and technicians.
There is limited evidence that exposure to 2-mercaptobenzothiazole may increase the risk of bladder cancer.6 2-Mercaptobenzothiazole is used in rubber vulcanization, and exposure may occur in the chemical, rubber, or tire manufacturing industries. The number of people occupationally exposed in Canada is not known. Exposure may also occur through skin contact with rubber goods and materials.
Environmental exposure to arsenic and inorganic arsenic compounds via ingestion of contaminated drinking water increases the risk of bladder cancer.7 It is not clear how many Canadians may be exposed to arsenic-contaminated drinking water. Levels are generally very low, but can vary geographically.8 Occupational arsenic exposure has not been linked to increased risk of bladder cancer, although exposure does occur. Most of these workers are exposed through contact with arsenic-containing wood preservatives.9
Exposure to x- and gamma-radiation also increases the risk of bladder cancer, although the evidence comes from studies of atomic bomb survivors and those exposed to medical radiation, not occupationally-exposed workers.10 Approximately 38,000 Canadians are exposed to ionizing radiation at work, which includes x- and gamma-radiation as well as other types.11 The largest occupational groups are medical radiation technologists and nurses.
Diesel engine exhaust was upgraded to a Group 1 definite human carcinogen by the International Agency for Research on Cancer in 2012. There is limited evidence that occupational exposure to diesel engine exhaust may increase the risk of bladder cancer.12 CAREX Canada estimates that approximately 897,000 Canadians are occupationally exposed to diesel engine exhaust, and environmental exposure is also a concern.13 The occupational groups with the largest number of exposed workers include drivers (truck, bus, subway, and taxi), heavy equipment operators, material handlers, mechanics, and firefighters.
There is also limited evidence that exposure to soot may increase the risk of bladder cancer, based on studies of chimney sweeps.1 There is no data available for how many Canadians may be exposed to soot. However, approximately 307,000 Canadians are occupationally exposed to polycyclic aromatic hydrocarbons (PAHs), which are a major component of soot.14 Major industries include restaurants, gas stations, and firefighting.
For more information on these exposures, see the CAREX Canada carcinogen profiles:
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IARC updated its classification process, which evaluates potential carcinogens based on the likelihood that they can cause cancer, in 2019.