Long-term exposure to PM2.5 and its constituents and risk of Non-Hodgkin lymphoma in Denmark: A population-based case–control study

Tahir Taj*, Aslak Harbo Poulsen, Matthias Ketzel, Camilla Geels, Jørgen Brandt, Jesper Heile Christensen, Robin Puett, Ulla Arthur Hvidtfeldt, Mette Sørensen, Ole Raaschou-Nielsen

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review


Background: Particulate matter (PM) air pollution is a complex mixture and the various PM constituents likely affect health differently. The literature on the relationships among specific PM constituents and the risk of cancer is sparse. In this study, we aimed to evaluate the association of PM2.5 and its constituents with the incidence of non-Hodgkin lymphoma (NHL) and the two main NHL subtypes. Methods: We undertook a nationwide register-based case-control study including 20,847 cases registered in the Danish Cancer Registry with NHL between 1989 and 2014. Among the entire Danish population, we selected 41,749 age and sex-matched controls randomly from the Civil Registration System. We assessed modelled outdoor PM concentrations at addresses of cases and controls with a state-of-the-art multi scale air pollution modelling system and used conditional logistic regression to estimate odds ratios (ORs) adjusted for individual and neighborhood level socio-demographic variables. Results: The 10-year time-weighted average concentrations of PM2.5, primary carbonaceous particles (BC/OC), secondary inorganic aerosols (SIA), secondary organic aerosols (SOA) and sea salt were 17.4, 2.3, 7.8, 0.3, and 4.1 μg/m3, respectively among controls. The results showed higher risk for NHL in association with exposure to BC/OC (OR = 1.03; 95% CI: 1.00, 1.07, per interquartile range (IQR)) and SOA (OR = 1.54; 95% CI: 1.13, 2.09, per IQR). The results indicated a higher risk for follicular lymphoma in association with several PM components. Including PM2.5 (OR = 1.16; 95% CI: 0.98–1.38), BC/OC (OR = 1.05; 95% CI: 0.97–1.14), SIA (OR = 1.44; 95% CI: 0.80–1.08), SOA (OR = 4.52; 95% CI: 0.86–23.83) per IQR. Conclusion: This is the first study on PM constituents and the risk of NHL. The results indicated an association with primary carbonaceous and secondary organic PM. The results need replication in other settings before any firm conclusion can be reached.

Original languageEnglish
Article number109762
JournalEnvironmental Research
Publication statusPublished - Sep 2020
Externally publishedYes

Bibliographical note

Funding Information:
The research was funded by Nordforsk under the Nordic Programme on Health and Welfare (Project #75007 : NordicWelfAir - Understanding the link between Air pollution and Distribution of related Health Impacts and Welfare in the Nordic countries). The funding source had no involvement in the study design, collection, analysis, interpretation, writing and decision to submit for publication.


  • Case–control study
  • Non-hodgkin lymphoma
  • Particulate matter

Cite this