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FELA

FELA

Scientific Support for Railroad Worker Injury and Illness Claims

RoseyFields provides scientific exposure assessment services in support of Federal Employers Liability Act (FELA) cases involving railroad worker injury and illness.
Our work focuses on evaluating occupational exposure conditions associated with railroad operations and determining their relevance to alleged health outcomes.

We support attorneys with objective, science-based analysis developed to meet the evidentiary standards required in litigation.

What We Do

Our team reconstructs historical exposure scenarios common in railroad environments, including diesel exhaust, asbestos-containing materials, silica, solvents, and other chemical agents. Evaluations are based on job duties, work environments, timeframes, and industry practices.

Our analyses address key exposure factors such as pathway, duration, frequency, and intensity, and are supported by peer-reviewed literature and accepted scientific methods. Deliverables are prepared for use in expert reports, deposition, mediation, and trial.

FELA Diesel Exposure Expert Witness

RoseyFields evaluates historical railroad diesel exhaust exposure in FELA matters involving locomotive engineers, conductors, machinists, maintenance personnel, track workers, shop employees, and other railroad occupations. Exposure reconstruction may incorporate locomotive type, job duties, work locations, ventilation, idling, engine maintenance, historical industrial hygiene measurements, published railroad studies, task frequency and duration, and changes in equipment and work practices over time. RoseyFields can evaluate diesel particulate matter, benzene, fuels, solvents, creosote, and other relevant co-exposures and, where sufficient data exist, estimate cumulative occupational exposure for comparison with toxicological and epidemiological evidence.

Related pages:

Related case studies:

Occupational exposures covered on this page:

The following summarizes peer-reviewed and regulatory literature on occupational exposures commonly encountered in railroad operations and their documented associations with disease. Content is organized by contaminant, with in-text citations in author-date format and a full reference list following each section. This material is intended as a general scientific and educational reference and does not constitute a case-specific expert opinion.

Asbestos

Asbestos was widely used across the railroad industry for decades in locomotive boiler and pipe insulation, brake linings, gaskets, and insulation throughout shop buildings and rolling stock, exposing operating and shop craft employees to airborne fibers during maintenance, repair, and demolition work. The International Agency for Research on Cancer (IARC) classifies all forms of asbestos as a Group 1 human carcinogen, and decades of occupational epidemiology have linked inhaled asbestos fibers to malignant mesothelioma, lung cancer, and asbestosis. A large French case-control study of men with documented occupational exposure found a clear dose-response relationship between cumulative asbestos exposure and pleural mesothelioma, with the odds of disease rising sharply as cumulative fiber-years increased (LaCourt, 2014).

Beyond mesothelioma, asbestos exposure is consistently associated with elevated lung cancer risk. A pooled analysis of 14 case-control studies encompassing nearly 40,000 subjects found that men with any history of occupational asbestos exposure had significantly increased odds of lung cancer after adjustment for smoking history (Olsson et al., 2017). Chronic inhalation of asbestos fibers also produces asbestosis, a progressive, non-malignant scarring of lung tissue; a nationwide Scandinavian cohort study of more than 1.5 million workers found that the incidence of asbestosis rose in direct proportion to cumulative fiber-year exposure (Iversen et al., 2024). A 2025 systematic review and meta-analysis further found that occupational asbestos exposure is associated with statistically significant increases in gastrointestinal cancers, including of the stomach, esophagus, and colorectum, with the strongest associations observed in the highest-exposure subgroups (Koehoorn et al., 2025).

The evidence for asbestos-related cancer extends to the genitourinary and upper aerodigestive tracts as well. A Canadian population-based case-control study found that men with more than 20 years since first asbestos exposure had more than double the odds of developing bladder cancer compared to unexposed men (Latifovic et al., 2020). A pooled international case-control study of laryngeal cancer found increased odds of disease among men with 30 or more years of asbestos exposure (Hall et al., 2020), and a ten-year cohort follow-up of more than 13,000 previously exposed male workers found a dose-dependent increase in mortality from head and neck cancers excluding the larynx (Clin et al., 2022).

References

  1. LaCourt, A., et al. (2014). Occupational and non-occupational attributable risk of asbestos exposure for mesothelioma. Thorax. https://doi.org/10.1136/thoraxjnl-2013-203744
  2. Olsson, A. C., Vermeulen, R., Schüz, J., et al. (2017). Exposure-response analyses of asbestos and lung cancer subtypes in a pooled analysis of case-control studies. Epidemiology, 28(2), 288–299. https://pubmed.ncbi.nlm.nih.gov/28141674/
  3. Iversen, I. B., et al. (2024). The asbestos–asbestosis exposure–response relationship: a cohort study of the general working population. Scandinavian Journal of Work, Environment & Health. https://doi.org/10.5271/sjweh.4153
  4. Koehoorn, M., et al. (2025). Occupational asbestos exposure and gastrointestinal cancers: systematic review and meta-analyses. Occupational and Environmental Medicine. https://pubmed.ncbi.nlm.nih.gov/39929711/
  5. Latifovic, L., et al. (2020). Silica and asbestos exposure at work and the risk of bladder cancer in Canadian men. BMC Cancer. https://pubmed.ncbi.nlm.nih.gov/32126982/
  6. Hall, A. L., et al. (2020). Laryngeal cancer risks in workers exposed to lung carcinogens: exposure-effect analyses using a quantitative job exposure matrix. Epidemiology. https://doi.org/10.1097/ede.0000000000001120
  7. Clin, B., et al. (2022). Head and neck cancer and asbestos exposure. Occupational and Environmental Medicine. https://doi.org/10.1136/oemed-2021-108047

Silica

Crystalline silica dust is generated in railroad operations through activities including sandblasting, track ballast handling, foundry casting of metal parts, and concrete and masonry work at rail facilities. IARC classifies crystalline silica as a Group 1 human carcinogen, based primarily on its association with lung cancer, and OSHA's respirable crystalline silica standard sets a permissible exposure limit of 50 micrograms per cubic meter as an eight-hour time-weighted average. A cohort study of 7,665 iron miners followed for a median of nearly 43 years found that workers in the highest silica exposure group had significantly increased lung cancer mortality relative to unexposed workers, with a statistically significant exposure-response trend (Lai et al., 2018).

Chronic silica dust inhalation produces well-documented non-malignant respiratory disease as well. A systematic review and meta-analysis found a significantly increased pooled odds of pulmonary fibrosis among workers with any history of occupational silica dust exposure (Gandhi et al., 2024). A Swedish cohort study of 1,752 iron foundry workers found significantly elevated standardized incidence ratios for chronic obstructive pulmonary disease across the cumulative silica exposure categories examined (Lenander-Ramirez et al., 2022).

Silica exposure has also been associated with several extrapulmonary cancers. A Canadian population-based case-control study found significantly elevated odds of bladder cancer among men with 27 or more years of silica exposure (Latifovic et al., 2020), and a pooled international case-control study found increased odds of laryngeal cancer among ever-exposed workers (Hall et al., 2020). A German cohort study of more than 17,000 porcelain industry workers found significantly elevated pancreatic cancer mortality (Birk et al., 2009), and a historical cohort study of Hong Kong silicosis patients found more than double the expected esophageal cancer mortality, with the highest risk observed among caisson workers exposed to the most severe silica dust concentrations (Yu et al., 2005).

References

  1. Lai, H., et al. (2018). Combined effect of silica dust exposure and cigarette smoking on total and cause-specific mortality in iron miners: a cohort study. Environmental Health. https://pubmed.ncbi.nlm.nih.gov/29743082/
  2. Gandhi, S. A., et al. (2024). The impact of occupational exposures on the risk of idiopathic pulmonary fibrosis: a systematic review and meta-analysis. Annals of the American Thoracic Society. https://www.atsjournals.org/doi/full/10.1513/AnnalsATS.202305-402OC
  3. Lenander-Ramirez, et al. (2022). Respirable dust and silica respiratory diseases among Swedish iron foundry workers. Journal of Occupational and Environmental Medicine. https://doi.org/10.1097/JOM.0000000000002533
  4. Latifovic, L., et al. (2020). Silica and asbestos exposure at work and the risk of bladder cancer in Canadian men. BMC Cancer. https://pubmed.ncbi.nlm.nih.gov/32126982/
  5. Hall, A. L., et al. (2020). Laryngeal cancer risks in workers exposed to lung carcinogens: exposure-effect analyses using a quantitative job exposure matrix. Epidemiology. https://doi.org/10.1097/ede.0000000000001120
  6. Birk, T., et al. (2009). Mortality in the German porcelain industry 1985–2005: first results of an epidemiological cohort study. Journal of Occupational and Environmental Medicine. https://doi.org/10.1097/jom.0b013e3181973e19
  7. Yu, I. T. S., et al. (2005). Further evidence for a link between silica dust and esophageal cancer. International Journal of Cancer. https://doi.org/10.1002/ijc.20764

Diesel Exhaust

Locomotive engineers, conductors, brakemen, and shop personnel who work in and around diesel-electric locomotives are exposed to diesel exhaust throughout their careers, particularly in enclosed cabs, engine houses, and rail yards where exhaust can accumulate. IARC classifies diesel engine exhaust as a Group 1 human carcinogen based primarily on its association with lung cancer. Among the earliest and most directly relevant occupational studies on this question was a case-control study of railroad workers, which found that workers with 20 or more years of diesel exhaust exposure had significantly increased odds of lung cancer after adjusting for smoking and asbestos exposure (Garschick et al., 1987). A companion cohort study of more than 55,000 railroad workers similarly found elevated lung cancer odds among workers aged 40 to 44 with documented diesel exhaust exposure (Larkin et al., 2000).

More recent systematic reviews have extended this evidence to other organ systems. A 2020 pooled case-control analysis of U.S. and Spanish bladder cancer patients found that diesel exhaust exposure, measured using respirable elemental carbon as a biomarker, was associated with significantly increased odds of bladder cancer (Koutros et al., 2020). A 2024 meta-analysis of 15 cohort studies found a modest but statistically significant increase in kidney cancer risk among workers with any history of diesel exhaust exposure (Collatuzzo et al., 2024). Diesel exhaust exposure has also been linked to hematologic malignancy: an extended follow-up of the Diesel Exhaust in Miners Study cohort found a significant increase in multiple myeloma risk associated with cumulative, lagged exposure to respirable elemental carbon (Koutros et al., 2023).

Diesel exhaust exposure has additionally been associated with cancers of the head and neck and with pancreatic cancer. A 2024 systematic review and meta-analysis of 15 cohort studies found statistically significant increases in both overall head and neck cancer and laryngeal cancer specifically among workers with occupational diesel exhaust exposure (Seyyedsalehi et al., 2024). A separate 2024 systematic review and meta-analysis reported a modest but statistically significant increase in pancreatic cancer risk associated with occupational diesel exhaust exposure (Sassano et al., 2024).

References

  1. Garschick, E., et al. (1987). A case-control study of lung cancer and diesel exhaust exposure in railroad workers. American Review of Respiratory Disease. https://doi.org/10.1164/arrd.1987.135.6.1242
  2. Larkin, E. K., et al. (2000). Diesel exhaust exposure and lung cancer: adjustment for the effect of smoking in a retrospective cohort study. American Journal of Industrial Medicine.
  3. Koutros, S., et al. (2020). Diesel exhaust and bladder cancer risk by pathologic stage and grade subtypes. Environment International. https://pubmed.ncbi.nlm.nih.gov/31864026/
  4. Collatuzzo, G., et al. (2024). Occupational-related exposure to diesel exhaust and kidney cancer: systematic review and meta-analysis. La Medicina del Lavoro. https://mattioli1885journals.com/index.php/lamedicinadellavoro/article/view/17014
  5. Koutros, S., et al. (2023). Diesel exhaust exposure and cause-specific mortality in the Diesel Exhaust in Miners Study II (DEMS II) cohort. Environmental Health Perspectives. https://pubmed.ncbi.nlm.nih.gov/37549097/
  6. Seyyedsalehi, M. S., et al. (2024). Occupational exposure to diesel exhaust and head and neck cancer: a systematic review and meta-analysis of cohort studies. European Journal of Cancer Prevention. https://doi.org/10.1097/CEJ.0000000000000876
  7. Sassano, M., et al. (2024). Occupational exposure to diesel exhausts and liver and pancreatic cancers: a systematic review and meta-analysis. European Journal of Epidemiology. https://doi.org/10.1007/s10654-024-01099-4 [journal name corrected from source record — see cover note]

Benzene

Benzene is a component of petroleum-based fuels, solvents, and degreasing agents historically used throughout railroad operations, including locomotive fueling, engine cleaning, and parts washing. IARC classifies benzene as a Group 1 human carcinogen, and its carcinogenicity is most strongly established for leukemia. A 2010 systematic review and meta-analysis of 15 studies found that workers with cumulative benzene exposure exceeding 100 ppm-years had more than three times the risk of acute myeloid leukemia compared to unexposed workers, with pooled estimates showing a clear dose-response relationship (Khalade et al., 2010).

The evidence linking benzene to hematologic malignancy extends beyond acute myeloid leukemia. A meta-analysis of 22 cohort and case-control studies found a statistically significant summary relative risk for non-Hodgkin lymphoma among benzene-exposed workers (Steinmaus et al., 2008). Benzene exposure has also been associated with genitourinary cancers: a 2025 systematic review and meta-analysis of 41 studies found a significant increase in kidney and unspecified urinary tract cancers among occupationally exposed workers (Seyyedsalehi et al., 2025), and a case-control study using New England bladder cancer data found significantly elevated odds of bladder cancer among workers in the highest quartile of cumulative benzene exposure (Xie et al., 2024).

More recent occupational cohort research has identified associations between benzene exposure and additional cancer sites. A 2025 case-cohort study of Norwegian offshore petroleum workers found that men with 17 to 34 years of benzene exposure had a significantly increased hazard of colorectal cancer, with a clear dose-response trend by exposure intensity (Babigumira et al., 2025). A 2025 systematic review and meta-analysis of 36 studies found a significant increase in nervous system cancers, including brain cancer, among benzene-exposed workers (Mangiaterra et al., 2025), and a large prospective cohort study of Chinese men found a significant, dose-dependent increase in stomach cancer risk among workers with the highest cumulative benzene exposure (DeMoulin et al., 2024).

References

  1. Khalade, A., et al. (2010). Exposure to benzene at work and the risk of leukemia: a systematic review and meta-analysis. Environmental Health. https://doi.org/10.1186/1476-069X-9-31
  2. Steinmaus, C., et al. (2008). Meta-analysis of benzene exposure and non-Hodgkin lymphoma: biases could mask an important association. Occupational and Environmental Medicine. https://doi.org/10.1136/oem.2007.036913
  3. Seyyedsalehi, M. S., et al. (2025). Occupational benzene exposure and risk of kidney and bladder cancers: a systematic review and meta-analysis. European Journal of Cancer Prevention. https://pubmed.ncbi.nlm.nih.gov/39229942/
  4. Xie, et al. (2024). Occupational exposure to organic solvents and risk of bladder cancer. Journal of Exposure Science & Environmental Epidemiology. https://pubmed.ncbi.nlm.nih.gov/38365975/
  5. Babigumira, R., et al. (2025). Benzene exposure and risk of colorectal cancer by anatomical subsite in the Norwegian offshore petroleum workers cohort. Environmental Research. https://doi.org/10.1016/j.envres.2025.121407
  6. Mangiaterra, et al. (2025). Occupational benzene exposure and risk of nervous system cancers: a systematic review and meta-analysis. Cancer Epidemiology. https://doi.org/10.1016/j.canep.2025.102779
  7. DeMoulin, D., et al. (2024). Occupational benzene exposure and cancer risk among Chinese men: a report from the Shanghai Men's Health Study. Cancer Epidemiology, Biomarkers & Prevention. https://pubmed.ncbi.nlm.nih.gov/39145717/

Chlorinated Solvents — Trichloroethylene (TCE)

Trichloroethylene has long been used as a metal degreasing agent in railroad shop operations, particularly for cleaning diesel engine parts and components. IARC classifies TCE as a Group 1 human carcinogen, with kidney cancer identified as the cancer type most strongly and consistently associated with occupational exposure. A prospective cohort study following 997 male train repair workshop workers for 50 years found an elevated standardized incidence ratio for kidney cancer among workers with documented TCE exposure from degreasing operations (Buhagen et al., 2016).

Additional occupational cohorts have identified TCE-associated cancer risk at other sites. A 2024 case-control study of testicular germ cell tumors found significantly increased odds of disease among men with TCE exposure assigned through a job-exposure matrix (Guth et al., 2024). A Canadian case-cohort study similarly found significantly elevated odds of rectal cancer associated with occupational TCE exposure (Pelland-St-Pierre et al., 2023), and a French population-based case-control study of head and neck squamous cell carcinoma found more than double the odds of disease among individuals with a history of TCE exposure (Carton et al., 2017).

TCE exposure has also been linked to liver cancer, chronic lymphocytic leukemia, and prostate cancer in the occupational epidemiology literature. A pooled cohort analysis of more than 5,500 workers across Finland, Sweden, and Denmark, individually monitored for TCE uptake, found a significant increase in primary liver cancer incidence (Hansen et al., 2013). A pooled international case-control study found a doubling of chronic lymphocytic leukemia risk among workers with high-probability TCE exposure (Cocco et al., 2013), and a retrospective cohort study of Marines and Navy personnel exposed to TCE-contaminated drinking water at Camp Lejeune found significantly elevated prostate cancer mortality (Bove et al., 2014).

References

  1. Buhagen, M., et al. (2016). Association between kidney cancer and occupational exposure to trichloroethylene. Journal of Occupational and Environmental Medicine. https://pubmed.ncbi.nlm.nih.gov/27465103/
  2. Guth, et al. (2024). Occupational exposure to organic solvents and the risk of developing testicular germ cell tumors (TESTIS study). Scandinavian Journal of Work, Environment & Health. https://doi.org/10.5271/sjweh.4161
  3. Pelland-St-Pierre, et al. (2023). Occupational exposure to endocrine disruptors and colorectal cancer risk in two Canadian cohorts. Occupational and Environmental Medicine. https://oem.bmj.com/content/80/Suppl_1/A81.3.abstract
  4. Carton, M., et al. (2017). Occupational exposure to solvents and risk of head and neck cancer in women: a population-based case-control study in France. BMJ Open. https://doi.org/10.1136/bmjopen-2016-012833
  5. Hansen, J., et al. (2013). Risk of cancer among workers exposed to trichloroethylene: analysis of three Nordic cohort studies. Journal of the National Cancer Institute. https://pubmed.ncbi.nlm.nih.gov/23723420/
  6. Cocco, P., et al. (2013). Occupational exposure to trichloroethylene and risk of non-Hodgkin lymphoma and its major subtypes: a pooled InterLymph analysis. Occupational and Environmental Medicine. https://oem.bmj.com/content/70/Suppl_1/A129.2
  7. Bove, F. J., et al. (2014). Evaluation of mortality among Marines and Navy personnel exposed to contaminated drinking water at USMC Base Camp Lejeune: a retrospective cohort study. Environmental Health. https://ehjournal.biomedcentral.com/articles/10.1186/1476-069X-13-10

Chlorinated Solvents — Tetrachloroethylene (PCE)

Tetrachloroethylene (perchloroethylene, or PCE) has been used in railroad shop and cleaning operations as a degreasing and dry-cleaning solvent, and workers handling railroad linens, uniforms, and parts cleaning have historically faced occupational exposure. IARC classifies PCE as a Group 2A probable human carcinogen. A French population-based case-control study of women found that occupational PCE exposure was associated with nearly triple the odds of head and neck squamous cell carcinoma (Carton et al., 2017), and a companion case-control study of French men found that high PCE exposure was associated with nearly four times the odds of laryngeal cancer specifically (Barul et al., 2017).

PCE exposure has also been linked to cancers of the urinary and hepatobiliary systems. A meta-analysis of occupational cohort studies found a statistically significant pooled relative risk for bladder cancer among PCE-exposed workers (Vlaanderen et al., 2013a). A nested case-control study within the Nordic Occupational Cancer Study cohort, encompassing nearly 24,000 liver cancer cases, found an elevated hazard ratio for primary liver cancer among workers with high combined PCE exposure (Vlaanderen et al., 2013b), consistent with dose-related increases in hepatocellular tumors observed in a National Toxicology Program inhalation bioassay in rats and mice (National Toxicology Program, 1986).

The occupational cohort literature on dry-cleaning workers, among the most heavily PCE-exposed populations, provides additional relevant evidence. An updated mortality study of 1,708 dry-cleaning workers found a statistically significant excess of mortality from cancers of the trachea, bronchus, and lung (Ruder et al., 2001). An earlier cohort mortality study of more than 5,300 dry-cleaning union members similarly found a statistically significant excess of esophageal cancer mortality, with the highest standardized mortality ratio observed among workers with the greatest cumulative solvent exposure (Blair et al., 1990).

References

  1. Carton, M., et al. (2017). Occupational exposure to solvents and risk of head and neck cancer in women: a population-based case-control study in France. BMJ Open. https://doi.org/10.1136/bmjopen-2016-012833
  2. Barul, C., et al. (2017). Occupational exposure to chlorinated solvents and risk of head and neck cancer in men: a population-based case-control study in France. Environmental Health. https://doi.org/10.1186/s12940-017-0286-5
  3. Vlaanderen, J., et al. (2013a). Occupational exposure to tetrachloroethylene and risk of bladder cancer: a meta-analysis. Occupational and Environmental Medicine. https://pubmed.ncbi.nlm.nih.gov/24659585/
  4. Vlaanderen, J., et al. (2013b). Occupational exposure to trichloroethylene and perchloroethylene and the risk of lymphoma, liver, and kidney cancer in four Nordic countries. Occupational and Environmental Medicine. https://pubmed.ncbi.nlm.nih.gov/23447073/
  5. National Toxicology Program. (1986). Toxicology and carcinogenesis studies of tetrachloroethylene (perchloroethylene) in F344/N rats and B6C3F1 mice (inhalation studies). NTP Technical Report Series. [Animal bioassay, cited for mechanistic support]
  6. Ruder, A. M., et al. (2001). Mortality in dry-cleaning workers: an update. American Journal of Industrial Medicine. https://doi.org/10.1002/1097-0274(200102)39:2%3C121::aid-ajim1000%3E3.0.co;2-h
  7. Blair, A., et al. (1990). Cancer and other causes of death among a cohort of dry cleaners. British Journal of Industrial Medicine. https://doi.org/10.1136/oem.47.3.162

Welding Fumes

Welding is a routine part of railroad maintenance-of-way and shop craft work, from rail and frog repair to fabrication and repair of rolling stock, exposing welders to a complex mixture of metal fumes including manganese, chromium, and nickel compounds. In 2017, IARC reclassified welding fume exposure as a Group 1 human carcinogen based on sufficient evidence of an association with lung cancer. A 2019 meta-analysis of 37 case-control and cohort studies found that workers who had ever welded had significantly increased lung cancer risk regardless of steel type, welding method, or region, with the association persisting independent of smoking and asbestos exposure (Honaryar et al., 2019).

Welding fume exposure has also been linked to cancers of the head and neck and to chronic respiratory disease. A 2025 systematic review and meta-analysis found significantly elevated risk of head and neck cancer overall, and of laryngeal cancer specifically, among workers with occupational welding fume exposure (Siea et al., 2025). A Canadian cohort study comparing more than 1,000 welders to a comparison group of electrical trades workers found a significantly elevated hazard of physician-diagnosed chronic obstructive pulmonary disease and bronchitis among welders (Galarneau et al., 2024). A 2023 systematic review and meta-analysis of seven cohort studies additionally found significantly increased kidney cancer risk among welders (Collatuzzo et al., 2023).

The evidence extends to genitourinary and other outcomes as well. A population-based cohort study found significantly elevated odds of bladder cancer among workers with a history of welding-related occupational tasks and exposures (Reed et al., 2020), and a retrospective occupational cohort study of vehicle manufacturing workers found more than double the hazard of lung-related disease among welders compared to non-welders, based on quantitative environmental monitoring of airborne particulate matter and metal constituents (Li et al., 2022). A 2025 French case-control study found significantly increased odds of testicular germ cell tumors among men with cumulative occupational exposure to welding fumes (Bijoux et al., 2025).

References

  1. Honaryar, M. K., Lunn, R. M., Luce, D., et al. (2019). Welding fumes and lung cancer: a meta-analysis of case-control and cohort studies. Occupational and Environmental Medicine, 76(5), 331–340. https://pubmed.ncbi.nlm.nih.gov/30948521/
  2. Siea, A. C., et al. (2025). Welding fumes exposure and the risk of head and neck and gastrointestinal cancer: a systematic review and meta-analysis. La Medicina del Lavoro. https://doi.org/10.23749/mdl.v116i2.16092
  3. Galarneau, et al. (2024). Respiratory ill-health and welding exposures: a Canadian cohort study. American Journal of Industrial Medicine. [Link in source record did not resolve — verify before publication]
  4. Collatuzzo, et al. (2023). Risk of bladder, kidney and prostate cancer from occupational exposure to welding fumes: a systematic review and meta-analysis. International Archives of Occupational and Environmental Health.
  5. Reed, et al. (2020). A cross section survey of previous employments, tasks and exposures matched to cancer phenotypes. PLoS ONE. https://pubmed.ncbi.nlm.nih.gov/33085669/
  6. Li, et al. (2022). Risk for lung-related diseases associated with welding fumes in an occupational population: evidence from a Cox model. Frontiers in Public Health. https://doi.org/10.3389/fpubh.2022.990547
  7. Bijoux, et al. (2025). Occupational exposure to heavy metals and welding fumes and testicular germ cell tumours risk in a French case-control study. Occupational and Environmental Medicine. https://doi.org/10.1136/oemed-2024-EPICOHabstracts.4

Creosote / Polycyclic Aromatic Hydrocarbons (PAHs)

Creosote, a coal-tar-derived wood preservative historically used to treat railroad crossties and structural timber, contains a complex mixture of polycyclic aromatic hydrocarbons (PAHs), several of which IARC classifies as known or probable human carcinogens. Railroad track workers, carpenters, and shop personnel handling treated ties and timbers face inhalation and dermal exposure to PAH compounds. A large Swedish census-based cohort study of more than 1.9 million men found a statistically significant increase in urothelial (bladder) cancer risk associated with occupational creosote exposure, using a job-exposure matrix to assign exposure status (Steineck, 1989).

PAH exposure, whether from creosote or other combustion sources, has also been linked to hematologic and respiratory malignancy. A population-based case-control study of 420 acute myeloid leukemia cases found significantly increased odds of disease among individuals reporting occupational creosote exposure (Poynter et al., 2017). A large pooled analysis of 14 case-control studies conducted across Europe and Canada found a significant increase in lung cancer odds among men with any history of occupational PAH exposure, using benzo[a]pyrene as a quantitative exposure proxy (Olsson et al., 2022). A 2025 global ecological study using Global Burden of Disease data across 204 countries found that occupational PAH exposure was associated with more than double the relative risk of thyroid cancer mortality (Maleki et al., 2025).

PAH exposure has additionally been associated with a range of non-malignant respiratory outcomes relevant to railroad workers who handle creosote-treated materials. A cross-sectional NHANES-based study found that higher urinary concentrations of several PAH metabolites were significantly associated with increased odds of chronic obstructive pulmonary disease (Xiao et al., 2023). A case-control study similarly found that higher total urinary PAH metabolite levels were significantly associated with increased odds of adult-onset asthma (Huang et al., 2018), and a longitudinal study found a significant association between ambient PAH exposure and increased prevalence of chronic cough (Anyenda et al., 2016).

References

  1. Steineck, G. (1989). Industry-related urothelial carcinogens. American Journal of Industrial Medicine. https://onlinelibrary.wiley.com/doi/abs/10.1002/ajim.4700160212
  2. Poynter, J. N., et al. (2017). Chemical exposures and risk of acute myeloid leukemia and myelodysplastic syndromes in a population-based study. International Journal of Cancer. https://doi.org/10.1002/ijc.30420
  3. Olsson, A. C., Vermeulen, R., Schüz, J., et al. (2022). Occupational exposure to polycyclic aromatic hydrocarbons and lung cancer risk: results from a pooled analysis of case-control studies (SYNERGY). Cancer Epidemiology, Biomarkers & Prevention. https://pubmed.ncbi.nlm.nih.gov/35437574/
  4. Maleki, Z., et al. (2025). Occupational exposure and thyroid cancer: results of a global ecological study (1990–2019) using a generalized additive model. Journal of Health Sciences and Surveillance System. https://jhsss.sums.ac.ir/article_51081.html
  5. Xiao, Y., et al. (2023). Systemic inflammation mediates environmental polycyclic aromatic hydrocarbons to increase chronic obstructive pulmonary disease risk in United States adults: a cross-sectional NHANES study. Frontiers in Public Health. https://doi.org/10.3389/fpubh.2023.1248812
  6. Huang, X., et al. (2018). Urinary polycyclic aromatic hydrocarbon metabolites and adult asthma: a case-control study. Scientific Reports. https://doi.org/10.1038/s41598-018-25327-3
  7. Anyenda, E. O., et al. (2016). Associations of cough prevalence with ambient polycyclic aromatic hydrocarbons, nitrogen and sulphur dioxide: a longitudinal study. International Journal of Environmental Research and Public Health. https://doi.org/10.3390/ijerph13080800

Herbicides

Railroads have historically relied on herbicides, including glyphosate, 2,4-dichlorophenoxyacetic acid (2,4-D), and atrazine, to control vegetation along rights-of-way, exposing track and maintenance-of-way workers who mix, apply, or work in recently sprayed areas. IARC classifies glyphosate as a Group 2A probable human carcinogen. A prospective cohort study of 53,562 licensed pesticide applicators found that workers in the highest quartile of cumulative atrazine use had a significantly elevated, dose-dependent risk of kidney cancer when analyses were lagged by 25 years (Remigio et al., 2024). A cross-sectional NHANES-based study of men aged 50 and older similarly found significantly increased odds of prostate cancer with increasing urinary 2,4-D levels (Glover et al., 2024).

Herbicide exposure has also been linked to lymphoma and endocrine cancer. A systematic review and meta-analysis of 17 independent studies found a significant summary relative risk for non-Hodgkin lymphoma associated with occupational phenoxy herbicide exposure (Schinasi & Leon, 2014). A case-control study of Central California agricultural workers found significantly increased odds of thyroid cancer associated with glyphosate exposure, assessed using a validated geographic information system model (Omidakhsh et al., 2022). A cross-sectional NHANES study also found that higher urinary glyphosate concentrations were significantly associated with increased odds of chronic obstructive pulmonary disease (Shi et al., 2025).

The herbicide literature also documents pulmonary and upper aerodigestive tract effects. A large retrospective cohort study of more than 3.6 million male Vietnam veterans found that presumptive Agent Orange herbicide exposure was significantly associated with increased risk of idiopathic pulmonary fibrosis (Kaul et al., 2022). A systematic review of 12 case-control studies found significantly elevated risk of both pharyngeal and laryngeal cancer among individuals with more than 8 years of herbicide exposure (Leonel et al., 2021).

References

  1. Remigio, R. V., et al. (2024). An updated evaluation of atrazine-cancer incidence associations among pesticide applicators in the Agricultural Health Study cohort. Environmental Health Perspectives. https://pubmed.ncbi.nlm.nih.gov/38381478/
  2. Glover, F., et al. (2024). Exposure to the herbicide 2,4-dichlorophenoxyacetic acid and prostate cancer among U.S. adult men. World Journal of Urology. https://doi.org/10.1007/s00345-024-05336-z
  3. Schinasi, L., & Leon, M. E. (2014). Non-Hodgkin lymphoma and occupational exposure to agricultural pesticide chemical groups and active ingredients: a systematic review and meta-analysis. International Journal of Environmental Research and Public Health. https://www.mdpi.com/1660-4601/11/4/4449
  4. Omidakhsh, N., et al. (2022). Thyroid cancer and pesticide use in a Central California agricultural area: a case-control study. Journal of Clinical Endocrinology & Metabolism. https://doi.org/10.1210/clinem/dgac413
  5. Shi, et al. (2025). Association between urinary glyphosate concentrations and chronic obstructive pulmonary disease in USA participants: evidence from NHANES 2013–2018. International Journal of Chronic Obstructive Pulmonary Disease. https://doi.org/10.2147/COPD.S500429
  6. Kaul, B., et al. (2022). Agent Orange exposure and risk of idiopathic pulmonary fibrosis among U.S. veterans. American Journal of Respiratory and Critical Care Medicine. https://doi.org/10.1164/rccm.202112-2724OC
  7. Leonel, A. C. L. da S., et al. (2021). The pesticides use and the risk for head and neck cancer: a review of case-control studies. Medicina Oral, Patología Oral y Cirugía Bucal. https://doi.org/10.4317/medoral.23962

Secondhand Smoke

Railroad crew members historically shared enclosed cabs, cabooses, and crew quarters with coworkers who smoked, creating sustained secondhand tobacco smoke exposure independent of an individual worker's own smoking status. IARC classifies secondhand tobacco smoke as a Group 1 human carcinogen. A German case-control study of nonsmoking lung cancer patients found that workplace and vehicle-based environmental tobacco smoke exposure were both associated with significantly increased lung cancer odds, with vehicle exposure carrying more than double the odds of disease (Kreuzer et al., 2000).

Beyond lung cancer, secondhand smoke exposure has been associated with several additional malignancies in large population-based cohorts. A NHANES-based prospective cohort study of 25,794 U.S. adults found that high secondhand smoke exposure, confirmed using serum cotinine biomarkers, was associated with significantly increased hazard of both kidney cancer mortality and bladder cancer mortality relative to individuals with no tobacco smoke exposure (Zhang et al., 2022). A large Chinese population-based case-control study of nearly 3,000 esophageal cancer cases found significantly increased odds of disease among individuals ever exposed to environmental tobacco smoke (Jin et al., 2024). A large UK Biobank-based prospective cohort study also found that early-life secondhand smoke exposure was significantly associated with increased incidence of idiopathic pulmonary fibrosis later in life (Zhu et al., 2025).

Secondhand smoke exposure is also associated with cancer of the larynx, the thyroid, and with chronic respiratory disease. A 2024 systematic review and meta-analysis of 17 studies found significantly increased odds of laryngeal cancer among individuals with a history of passive smoking exposure (Xu et al., 2024). A 2025 global ecological study using Global Burden of Disease data across 204 countries and territories found a small but statistically significant increase in age-standardized thyroid cancer incidence associated with population-level secondhand smoke exposure (Maleki et al., 2025). A large prospective cohort study of more than 445,000 participants found that among lifelong nonsmokers, weekly secondhand smoke exposure was significantly associated with increased chronic obstructive pulmonary disease risk (Chen et al., 2024).

References

  1. Kreuzer, M., et al. (2000). Environmental tobacco smoke and lung cancer: a case-control study in Germany. American Journal of Epidemiology. https://pubmed.ncbi.nlm.nih.gov/10670548/
  2. Zhang, Z., Li, Z., Zhang, X., et al. (2022). Association between secondhand smoke and cancers in adults in the US population. Journal of Cancer Research and Clinical Oncology. https://pubmed.ncbi.nlm.nih.gov/35943599/
  3. Jin, Z.-Y., et al. (2024). Environmental tobacco smoking (ETS) and esophageal cancer: a population-based case-control study in Jiangsu Province, China. International Journal of Cancer. https://doi.org/10.1002/ijc.35254
  4. Xu, F., et al. (2024). Passive smoking and risk of head and neck cancer: a systematic review and meta-analysis. European Journal of Cancer Prevention. https://doi.org/10.1097/cej.0000000000000930
  5. Maleki, Z., et al. (2025). Relationship of modifiable risk factors with the incidence of thyroid cancer: a worldwide study. BMC Research Notes. https://doi.org/10.1186/s13104-024-07058-2
  6. Zhu, J., et al. (2025). Early-life exposure to tobacco smoke and the risk of idiopathic pulmonary fibrosis: a population-based cohort study. Annals of the American Thoracic Society. https://doi.org/10.1513/AnnalsATS.202409-906OC
  7. Chen, et al. (2024). The role of active and passive smoking in chronic obstructive pulmonary disease and systemic inflammation: a 12-year prospective study in China. Journal of Epidemiology and Global Health. https://doi.org/10.1007/s44197-024-00290-w

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