Lung cancer mortality and carbon black exposure: a nested case-control study at a German carbon black production plant

Our plain-English summary of Lung cancer mortality and carbon black exposure: a nested case-control study at a German carbon black production plant, by S.F. Büchte, P. Morfeld, J. Wellmann, et al (Journal of Occupational and Environmental Medicine, 2006).

The study

• Authors: S.F. Büchte, P. Morfeld, J. Wellmann, U. Bolm-Audorff, R.J. McCunney, C. Piekarski, International Carbon Black Association
• Journal: Journal of Occupational and Environmental Medicine
• Published: 2006;48(12):1242-52
• Cited by: 22 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: The objective of this study was to conduct a case-control study of lung cancer nested within a cohort of 1528 German carbon black workers, 1976-1998.

Methods: The authors conducted risk-set sampling of two controls matched on year of birth and conditional logistic regression modeling of cumulative carbon black exposure, duration of work in different departments, feedstock contact, asbestos exposure, smoking, age at hire, exposures before the carbon black job, and serving as a soldier in World War II or being a prisoner of war. Analyses were performed with both the full cohort and members of an inception cohort subset. Exposures were lagged by 10 years.

Results: Analysis of 50 lung cancer deaths showed no association to carbon black exposure.

Conclusions: Carbon black exposure was not linked to lung cancer risk. Suggestions of positive associations with asbestos exposure, feedstock contact, and work in specific departments are inconclusive due to small numbers.

In plain English

This nested case-control study examined lung cancer deaths among 1528 male German blue-collar workers at a carbon black plant. All 50 lung cancer deaths were compared with 100 controls matched on date of birth. Asbestos dust exposure was rated by plant staff without fiber measurements; no fiber type was named. The authors reported no positive association between cumulative carbon black exposure and lung cancer death. Four of 3290 models in subgroups hired from 1960 gave odds ratios above one, but the authors stated all were below one after excluding three ineligible cases. Ninety-two percent of cases and 84% of controls had ever had asbestos dust exposure. Per 10 asbestos category-years (a rating times years), the odds ratio was 1.37 (95% CI 0.98 to 1.90, not significant) in one model. It was 1.56 (significant) when both asbestos and carbon black were lagged 10 years. Expert-rated quartz exposure in outside jobs had an odds ratio of 5.06 (95% CI 1.68 to 15.27) in one model. The authors found no evidence carbon black acts as a lung carcinogen, noting limited power from few cases.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Nested case-control study within an existing worker cohort, analyzed with conditional logistic regression
• Who was studied: 50 men who died of lung cancer and 100 controls matched on date of birth (131 individuals in all). They were drawn from a cohort of 1528 male German blue-collar workers employed at least 1 year at a carbon black production plant between 1960 and 1998, with mortality followed from 1976.
• Exposure: Cumulative carbon black exposure, estimated with four exposure models (A to D). Also studied: time worked in the furnace black, lamp black and gas black sections; asbestos dust exposure at the plant, rated by senior safety staff as exposure category multiplied by years; contact with feedstock oil; smoking; exposures in jobs outside the plant, with quartz used as a surrogate; and World War II service or prisoner-of-war history.
• Main results:
  • Carbon black: after adjustment for prior exposures, the odds ratio per 100 carbon black score-unit-years was 0.35 (P 0.093, 95% CI 0.10 to 1.19) in study group 1 (50 cases, 100 controls).
  • Carbon black: none of the 4538 models fitted for study groups 1 and 2 gave an odds ratio for cumulative carbon black exposure greater than one.
  • Carbon black: of 3290 models fitted for study groups 3 and 4 (workers hired on or after January 1, 1960), four gave odds ratios greater than one. The authors stated that all adjustment combinations gave odds ratios below one after three cases that did not meet the inclusion criteria were excluded.
  • Asbestos prevalence: 92% of cases and 84% of controls in study group 1 had ever been exposed to asbestos dust at the plant. Among those exposed, mean cumulative exposure was 18.3 asbestos category-years for cases and 18.6 for controls.
  • Asbestos risk, unlagged: in the model adjusting for asbestos and feedstock oil (study group 1), the odds ratio per 10 asbestos category-years (exposure category multiplied by years) was 1.37 (P 0.062, 95% CI 0.98 to 1.90). This was not statistically significant.
  • Asbestos risk, lagged: when both carbon black and asbestos exposures were lagged 10 years (study group 1), the asbestos odds ratio was 1.56 (P 0.041). This was statistically significant.
  • Feedstock oil: 18% of cases and 15% of controls had ever had contact with feedstock oil. No significant positive association was found (odds ratio 1.56, P 0.516, in the Table 7 model).
  • Quartz outside the plant: in study group 1, expert-rated ever exposure to quartz in outside jobs had an odds ratio of 5.06 (P 0.004, 95% CI 1.68 to 15.27). This model was adjusted for age at hire, prisoner-of-war history and World War II participation. Other models gave different estimates.
• The authors' conclusion: The authors concluded that they found no evidence that carbon black acts as a lung carcinogen in these production workers. They considered their findings on other exposures, including asbestos, indicative at best because of the small number of cases.
• Limitations the authors state:
  • Limited statistical power because of the small number of cases
  • Sparse data may have produced spurious positive results
  • The asbestos exposure estimate was only qualitative; no fiber measurements were available
  • Variables for exposures outside the plant were only qualitative
  • Selection bias was not fully resolved

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Lung Cancer, nested case-control study, Case-Control Study, Asbestos Exposure.

Related studies

• Comparative proteomics and pulmonary toxicity of instilled single-walled carbon nanotubes, crocidolite asbestos, and ultrafine carbon black in mice — J.G. Teeguarden, B.J. Webb-Robertson, et al. (2011)
• Asbestos and man-made vitreous fibers as risk factors for diffuse malignant mesothelioma: results from a German hospital-based case-control study — K. Rödelsperger, K.H. Jöckel, et al. (2001)
• Exposure to nitrosamines, carbon black, asbestos, and talc and mortality from stomach, lung, and laryngeal cancer in a cohort of rubber workers — K. Straif, U. Keil, et al. (2000)
• Nested case-control study of autoimmune disease in an asbestos-exposed population — C.W. Noonan, J.C. Pfau, et al. (2006)
• Occupational exposures and male breast cancer: A nested case-control study in the Nordic countries — M. Talibov, J. Hansen, et al. (2019)
• Microstructures and nanostructures for environmental carbon nanotubes and nanoparticulate soots — L.E. Murr (2008)

Browse more research in Journal of Occupational and Environmental Medicine, or return to medical research.