A report has shed new light on the incidence of cancer in different occupational groups in Norway. The report Occupation and cancer shows that certain types of cancer, including lung cancer, are especially prevalent in construction and in some jobs in the manufacturing and service industries. Among women, a higher risk of lung cancer was found among painting and wallpapering workers. An increased risk of breast cancer was found in women doing jobs requiring higher educational qualifications.
Background
Cancer is a fairly common disorder, with the overall lifetime risk of developing cancer before the age of 75 being 33% for men and 27% for women. In 2007, 26,000 new cases of cancer were reported in Norway, 14,000 of which were in men. Several studies have attempted to estimate the proportion of work-related cancers, and a study based on Nordic data (Dreyer et al, 1997) estimated that in the year 2000, about 3% of all cancers in men and less than 0.1% in women in the Nordic countries could be attributed to known carcinogenic substances in the workplace.
Although occupational cancer is most commonly attributed to exposure to chemical substances in the workplace, it can also be due to exposure to other factors in the working environment, such as certain types of radiation.
About the survey
Information on exposure and cancer incidence in the report Occupation and Cancer (in Swedish, 657Kb PDF) (Eggen, T., et al, 2010) was largely derived from the Nordic Occupational Cancer Study (NOCCA) project. The study examined the incidence of cancer and occupational exposure to carcinogens among employees in the Nordic region.
Asbestos, silica, benzene, chromium, nickel, formaldehyde, wood dust and ionising radiation were some of the exposures at Norwegian workplaces shown to be carcinogenic to humans. Other factors, such as polycyclic aromatic hydrocarbons (PAHs), diesel exhaust, some chlorinated hydrocarbons and nightshift work, are considered as probably carcinogenic to humans.
Exposure to these factors was examined for several occupations. The data from the project was used to calculate the national exposure levels, based on a method described by Kauppinen et al (2009). Exposures were compiled by the number of employees in the various professions to provide an approximate estimate of how many people were exposed. Occupations were coded according to the Nordic occupational classification (NYK–1958).
Key findings and discussion
Although many forms of cancer can be linked to occupational exposure, there are big differences in how well a correlation can be documented. In the report, emphasis was put on cancers where a significant proportion of cases were attributable to occupational exposure. This included lung cancer (18%), mesothelioma (cancers of the breast and peritoneum, 83%), nasal and sinus cancer (30%), bladder cancer (2%) and laryngeal cancer (6%).
The occupational cancers investigated in this report were particularly prevalent among construction workers and craftsmen, but also exist in varying degrees for occupations in manufacturing, service industries, primary industry and shipping. Data from the survey also show that workers in these occupations in general seemed to be more commonly exposed to one or several of these factors compared to workers in other occupational categories.
Incidences of lung cancer, mesothelioma, nasal and sinus cancer, bladder cancer and laryngeal cancer were found to be especially elevated in the construction industries and among craftsmen. Elevated risks were also seen in some occupations in manufacturing industries and service industries. Among men, plumbers had a particularly increased risk of mesothelioma.
Women and cancer
Traditionally, women have had less occupational exposure due to gendered norms in career choices and lower labour force participation. Even so, the NOCCA study shows a particularly increased risk of lung cancer for female painting and wallpapering workers, as well as machinery and motor carriers, than in the general population. There is, however, some uncertainty associated with these findings.
Although an increased risk of mesothelioma is not widespread among female professionals, an increased risk of breast cancer in women was seen in a variety of jobs traditionally carried out by people with higher education qualifications. The risk increased, for example, among female managers in administration and management and in academia. This increased risk was primarily explained by the childbirth patterns among these women.
Commentary
Increased knowledge about cancer-causing factors has led authorities and employers to initiate several measures to protect workers against hazardous substances. The use of asbestos has been prohibited, and the use of substances such as quartz and benzene is strongly regulated.
Although such regulations have led to a decline in occupational exposure in Norway, some workers, especially those within the construction business, crafts and industry, are still exposed to factors that can lead to cancer.
References
Dreyer, L., Andersen, A. and Pukkala, E. (1997), ‘Avoidable cancers in the Nordic countries. Occupation’, APMIS Supplementum 76, Vol. 105, pp. 68–79.
Eggen, T., Lenvik, K., Grimsrud, T.K., Kjærheim, K., Aagestad, C. and Tynes, T. (2010), ‘Yrke og kreft’ [Occupation and cancer], STAMI report, Årg. 11, No. 3, National Institute of Occupational Health, Oslo.
Kauppinen, T., Heikkilä, P., Plato, N., Woldbæk, T., Lenvik, K., Hansen, J, et al (2009), ‘Construction of job-exposure matrices for the Nordic Occupational Cancer Study (NOCCA)’, Acta Oncologica, Vol. 48, No. 5, pp.791–800.
Bjørn Tore Langeland, National Institute of Occupational Health