The Burden of Occupational Cancer Study focused on common, well-established occupational carcinogens. Since the project started, IARC has reevaluated and upgraded a number of occupational agents, such as dichloromethane and the pesticides DDT, pentachlorophenol, and malathion. More are on their list of priorities for reevaluation in 2020-2024, such as perchloroethylene, acrylonitrile, and carbon nanotubes [1]. There are also many workplace exposures that have not been studied enough to fully understand their impact on health, or the extent to which workers may be exposed.
Below are some of the emerging or special interest exposures that could not be studied as part of the Burden Project.
Pesticides are used to protect plants from pests, including insects, weeds and fungi. IARC has evaluated a number of pesticides, and many have been reevaluated and upgraded in recent years. Lindane was classified as a definite carcinogen in 2018, while pentachlorophenol was upgraded from a possible to a definite carcinogen in 2019. Glyphosate, the most widely-used herbicide in Canada, is classified as a probable carcinogen, as are DDT, diazinon, malathion, dieldrin and aldrin [2,3,4].
Antineoplastic agents are drugs used to treat cancer. IARC has classified a number of antineoplastic agents as Group 1 carcinogens [5]. Healthcare workers may be exposed when preparing, dispensing and administering these drugs, and occupational exposure may also occur during receiving, storage, cleaning and disposal. CAREX Canada estimates that approximately 75,000 Canadians are occupationally exposed to antineoplastic agents; the majority are pharmacy technicians, nurses, and pharmacists [6].
Nanomaterials are sized between 1 and 100 nm in at least one dimension. There are many different types and shapes of nanomaterials with varying physical properties. They are used in many applications including construction, electronics and medicine [7,8,9]. The health risks of nanomaterials are not well understood, but there is concern that some carbon nanotubes are structurally similar to asbestos, and studies have found that a specific type of carbon nanotube causes mesothelioma in rodents [10]. More research is needed to fully understand current exposure to nanomaterials and the related health impact. Both nanomaterials and multi-walled carbon nanotubes are included in IARC’s list of priorities for evaluation by 2024 [1].
Sedentary behaviour is prolonged sitting or reclining while awake. Office work and driving are examples of jobs that may involve sedentary behaviour. There is some evidence that sedentary work may increase the risk of colon cancer, but overall there is a need for more research to understand the impact of sedentary work on health. IARC has included sedentary behaviour as a high priority for evaluation by 2024 [1].
Metalworking fluids are used to lubricate pieces of metal during processes such as machining, grinding, cutting, and milling. They can contain oils, emulsifiers, detergents, corrosion inhibitors, dyes, and other additives [12]. Exposure to metalworking fluids is associated with contact dermatitis, asthma, chronic bronchitis, and other health effects. They are a high priority for evaluation by IARC by 2024 [1].
