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Background: Globally, lung cancer is the most frequent occupational cancer, but the risk associated with the occupations or occupational environment in Iran is not clear. We aimed to assess occupations with the risk of lung cancer., Methods: We used the IROPICAN nationwide case-control study data including 658 incident lung cancer cases and 3477 controls. We assessed the risk of lung cancer in relation to ever working in major groups of International Standard Classification of Occupations, high-risk occupations for lung cancer and duration of employment and lung cancer subtype among construction workers and farmers while controlling for cigarette smoking and opium consumption. We used unconditional regression logistic models to estimate ORs for the association between increased lung cancer risk and occupations., Results: We observed elevated ORs for lung cancer in male construction workers (OR=1.4; 95% CI: 1.0 to 1.8), petroleum industry workers (OR=3.2; 95% CI: 1.1 to 9.8), female farmers (OR=2.6; 95% CI: 1.3 to 5.3) and female bakers (OR=5.5; 95% CI: 1.0 to 29.8). A positive trend by the duration of employment was observed for male construction workers (p< 0.001). Increased risk of squamous cell carcinoma was observed in male construction workers (OR=1.9; 95% CI: 1.2 to 3.0) and female farmers (OR=4.3; 95% CI: 1.1 to 17.2), who also experienced an increased risk of adenocarcinoma (OR=3.8; 95% CI: 1.4 to 9.9)., Discussion: Although we observed associations between some occupations and lung cancer consistent with the literature, further studies with larger samples focusing on exposures are needed to better understand the occupational lung cancer burden in Iran., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Exposure to extremely low frequency magnetic fields (ELF-MFs) and electric shocks is a common occupational risk factor in many workplaces. Recent investigations have highlighted a possible association between such exposures and lymphoma risk. This study was carried out to further explore the association between occupational exposure to ELF-MFs and electric shocks and risk of lymphoma in a large Nordic census-based cohort., Methods: We included cases of non-Hodgkin's lymphoma (NHL, n=68 978), chronic lymphocytic leukaemia (CLL, n=20 615) and multiple myeloma (MM, n=35 467) diagnosed between 1961 and 2005 in Finland, Iceland, Norway and Sweden. Cases were matched to five controls by year of birth, sex and country. Lifetime occupational ELF-MF and electric shock exposures were assigned to jobs reported in population censuses using job-exposure matrices. The risk of cancer was assessed based on cumulative exposure to ELF-MF and electric shocks. ORs with 95% CIs were estimated using logistic models adjusted for occupational co-exposures relevant to lymphomas., Results: Less than 7% of the cases experienced high levels of ELF-MF. We observed no increased risks among workers exposed to high levels of ELF-MF for NHL (OR: 0.93; CI 0.90 to 0.97), CLL (OR: 0.98; CI 0.92 to 1.05) or MM (OR: 0.96; CI 0.90 to 1.01)., Conclusion: Our results do not provide support for an association between occupational exposure to ELF-MFs and electric shocks and lymphoma risk., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: Animal bioassays have demonstrated convincing evidence of the potential carcinogenicity to humans of titanium dioxide (TiO 2 ), but limitations in cohort studies have been identified, among which is the healthy worker survivor effect (HWSE). We aimed to address this bias in a pooled study of four cohorts of TiO 2 workers., Methods: We reanalysed data on respirable TiO 2 dust exposure and lung cancer mortality among 7341 male workers employed in TiO 2 production in Finland, France, UK and Italy using the parametric g-formula, considering three hypothetical interventions: setting annual exposures at 2.4 (U.S. occupational exposure limit), 0.3 (German limit) and 0 mg/m 3 for 25 and 35 years., Results: The HWSE was evidenced. Taking this into account, we observed a positive association between lagged cumulative exposure to TiO 2 and lung cancer mortality. The estimated number of lung cancer deaths at each age group decreased across increasingly stringent intervention levels. At age 70 years, the estimated number of lung cancer deaths expected in the cohort after 35-year exposure was 293 for exposure set at 2.4 mg/m 3 , 235 for exposure set at 0.3 mg/m 3 , and 211 for exposure set at 0 mg/m 3 ., Conclusion: This analysis shows that HWSE can hide an exposure-response relationship. It also shows that TiO 2 epidemiological data could demonstrate an exposure-effects relationship if analysed appropriately. More epidemiological studies and similar reanalyses of existing cohort studies are warranted to corroborate the human carcinogenicity of TiO 2 . This human evidence, when combined with the animal evidence, strengthens the overall evidence of carcinogenicity of TiO 2 ., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: To assess the association between occupational exposure to asbestos and the risk of cholangiocarcinoma (CC)., Methods: We conducted a case-control study nested in the Nordic Occupational Cancer (NOCCA) cohort. We studied 1458 intrahepatic CC (ICC) and 3972 extrahepatic CC (ECC) cases occurring among subjects born in 1920 or later in Finland, Iceland, Norway and Sweden. Each case was individually matched by birth year, gender and country to five population controls. The cumulative exposure to asbestos (measured in fibres (f)/ml × years) was assessed by applying the NOCCA job-exposure matrix to data on occupations collected during national population censuses (conducted in 1960, 1970, 1980/81 and 1990). Odds ratios (OR) and 95% CI were estimated using conditional logistic regression models adjusted by printing industry work., Results: We observed an increasing risk of ICC with cumulative exposure to asbestos: never exposed, OR 1.0 (reference category); 0.1-4.9 f/mL × years, OR 1.1 (95% CI 0.9 to 1.3); 5.0-9.9 f/mL × years, OR 1.3 (95% CI 0.9 to 2.1); 10.0-14.9 f/mL × years, OR 1.6 (95% CI 1.0 to 2.5); ≥15.0 f/mL × years, OR 1.7 (95% CI 1.1 to 2.6). We did not observe an association between cumulative asbestos exposure and ECC., Conclusions: Our study provides evidence that exposure to asbestos might be a risk factor for ICC. Our findings also suggest that the association between ECC and asbestos is null or weaker than that observed for ICC. Further studies based on large industrial cohorts of asbestos workers and possibly accounting for personal characteristics and clinical history are needed., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Objectives: A potential impact of exposure to endocrine disruptors, including pesticides, during intrauterine life, has been hypothesised in testicular germ cell tumour (TGCT) aetiology, but exposure assessment is challenging. This large-scale registry-based case-control study aimed to investigate the association between parental occupational exposure to pesticides and TGCT risk in their sons., Methods: Cases born in 1960 or onwards, aged between 14 and 49 years, and diagnosed between 1978 and 2013 in Denmark, Finland, Norway or Sweden, were identified from the respective nationwide cancer registries. Four controls per case were randomly selected from the general national populations, matched on year of birth. Information on parental occupation was collected through censuses or Pension Fund information and converted into a pesticide exposure index based on the Finnish National Job-Exposure Matrix., Results: A total of 9569 cases and 32,028 controls were included. No overall associations were found for either maternal or paternal exposures and TGCT risk in their sons, with ORs of 0.83 (95% CI 0.56 to 1.23) and of 1.03 (0.92 to 1.14), respectively. Country-specific estimates and stratification by birth cohorts revealed some heterogeneity. Cryptorchidism, hypospadias and family history of testicular cancer were risk factors but adjustment did not change the main results., Conclusions: This is the largest study on prenatal exposure to pesticides and TGCT risk, overall providing no evidence of an association. Limitations to assess individual exposure in registry-based studies might have contributed to the null result., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Objectives: Firefighters are potentially exposed to a wide range of known and suspected carcinogens through their work. The objectives of this study were to examine the patterns of cancer among Nordic firefighters, and to compare them with the results from previous studies., Methods: Data for this study were drawn from a linkage between the census data for 15 million people from the five Nordic countries and their cancer registries for the period 1961-2005. SIR analyses were conducted with the cancer incidence rates for the entire national study populations used as reference rates., Results: A total of 16 422 male firefighters were included in the final cohort. A moderate excess risk was seen for all cancer sites combined, (SIR=1.06, 95% CI 1.02 to 1.11). There were statistically significant excesses in the age category of 30-49 years in prostate cancer (SIR=2.59, 95% CI 1.34 to 4.52) and skin melanoma (SIR=1.62, 95% CI 1.14 to 2.23), while there was almost no excess in the older ages. By contrast, an increased risk, mainly in ages of 70 years and higher, was observed for non-melanoma skin cancer (SIR=1.40, 95% CI 1.10 to 1.76), multiple myeloma (SIR=1.69, 95% CI 1.08 to 2.51), adenocarcinoma of the lung (SIR=1.90, 95% CI 1.34 to 2.62), and mesothelioma (SIR=2.59, 95% CI 1.24 to 4.77). By contrast with earlier studies, the incidence of testicular cancer was decreased (SIR=0.51, 95% CI 0.23 to 0.98)., Conclusions: Some of these associations have been observed previously, and potential exposure to polycyclic aromatic hydrocarbons, asbestos and shift work involving disruption of circadian rhythms may partly explain these results.

Background: Commercial airline crew is one of the occupational groups with the highest exposures to ionising radiation. Crew members are also exposed to other physical risk factors and subject to potential disruption of circadian rhythms., Methods: This study analyses mortality in a pooled cohort of 93 771 crew members from 10 countries. The cohort was followed for a mean of 21.7 years (2.0 million person-years), during which 5508 deaths occurred., Results: The overall mortality was strongly reduced in male cockpit (SMR 0.56) and female cabin crews (SMR 0.73). The mortality from radiation-related cancers was also reduced in male cockpit crew (SMR 0.73), but not in female or male cabin crews (SMR 1.01 and 1.00, respectively). The mortality from female breast cancer (SMR 1.06), leukaemia and brain cancer was similar to that of the general population. The mortality from malignant melanoma was elevated, and significantly so in male cockpit crew (SMR 1.57). The mortality from cardiovascular diseases was strongly reduced (SMR 0.46). On the other hand, the mortality from aircraft accidents was exceedingly high (SMR 33.9), as was that from AIDS in male cabin crew (SMR 14.0)., Conclusions: This large study with highly complete follow-up shows a reduced overall mortality in male cockpit and female cabin crews, an increased mortality of aircraft accidents and an increased mortality in malignant skin melanoma in cockpit crew. Further analysis after longer follow-up is recommended.

Objectives: A cluster of 11 cases of cholangiocarcinoma (CC) was observed in a small Japanese printing firm. To elucidate whether the identified cluster is indicative of an elevated risk of CC among workers in the printing industry at large, we explored the risk of cancer of the liver and CC among individuals employed in the printing industry in a large cohort set-up in four Nordic countries (Finland, Iceland, Norway and Sweden) over a period of 45 years., Methods: The cohort was set-up by linking occupational information from censuses to national cancer registry data utilising personal identity codes in use in all Nordic countries. We calculated standardised incidence ratios (SIRs) for men and women working in the printing industry, and stratified by occupational category (typographers, printers, lithographers, bookbinders)., Results: Among men, we observed elevated SIRs for cancer of the liver (1.35, 95% CI 1.14 to 1.60; 142 cases), specifically intrahepatic CC (2.34, 95% CI 1.45 to 3.57; 21 cases). SIRs for liver cancer were especially elevated among printers and lithographers, and SIRs for intrahepatic CC among typographers and printers. SIRs for extrahepatic CC were not elevated. SIRs for women followed a similar pattern but the number of cases was low., Conclusions: Our study supports the notion that the finding of excess CC risk among workers in a small Japanese printing firm possibly extends beyond this specific firm and country. Further studies should focus on the specific exposures that occur in the printing industry.

Objectives: Trichloroethylene (TCE) and Perchloroethylene (PER) are two chlorinated solvents that are applied widely as degreasers of metal parts, and in dry cleaning and other applications. In 2012, the International Agency for Research on Cancer classified TCE as carcinogenic to humans and PER as probably carcinogenic to humans. We explored exposure-response relations for TCE and PER and non-Hodgkin's lymphoma (NHL), multiple myeloma (MM), and cancers of the kidney and liver in the Nordic Occupational Cancer cohort., Methods: The cohort was set up by linking occupational information from censuses to national cancer registry data using personal identity codes in use in all Nordic countries. Country, time period, and job-specific exposure estimates were generated for TCE, PER and potentially confounding occupational exposures with a job-exposure matrix. A conditional logistic regression was conducted for exposure groups as well as for continuous cumulative exposure., Results: HRs for liver cancer, NHL and MM but not kidney cancer were slightly elevated in groups with high exposure to PER (compared to occupationally unexposed subjects). HRs for liver cancer and NHL also increased with increasing continuous exposure to PER. We did not observe evidence for an association between exposure to TCE and NHL, MM or liver and kidney cancer., Conclusions: Although this study was subject to limitations related to the low prevalence of exposure to PER and TCE in the Nordic population and a limited exposure assessment strategy, we observed some evidence indicative of an excess risk of cancer of the liver and NHL in subjects exposed to PER.

Based on the idea that electric light at night might account for a portion of the high and rising risk of breast cancer worldwide, it was predicted long ago that women working a non-day shift would be at higher risk compared with day-working women. This hypothesis has been extended more recently to prostate cancer. On the basis of limited human evidence and sufficient evidence in experimental animals, in 2007 the International Agency for Research on Cancer (IARC) classified 'shift work that involves circadian disruption' as a probable human carcinogen, group 2A. A limitation of the epidemiological studies carried out to date is in the definition of 'shift work.' IARC convened a workshop in April 2009 to consider how 'shift work' should be assessed and what domains of occupational history need to be quantified for more valid studies of shift work and cancer in the future. The working group identified several major domains of non-day shifts and shift schedules that should be captured in future studies: (1) shift system (start time of shift, number of hours per day, rotating or permanent, speed and direction of a rotating system, regular or irregular); (2) years on a particular non-day shift schedule (and cumulative exposure to the shift system over the subject's working life); and (3) shift intensity (time off between successive work days on the shift schedule). The group also recognised that for further domains to be identified, more research needs to be conducted on the impact of various shift schedules and routines on physiological and circadian rhythms of workers in real-world environments.