Tahir Taj1, Aslak Harbo Poulsen2, Matthias Ketzel3, Camilla Geels4, Jørgen Brandt4, Jesper Heile Christensen4, Robin Puett5, Ulla Arthur Hvidtfeldt2, Mette Sørensen6, Ole Raaschou-Nielsen7. 1. Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen Ø, Denmark. Electronic address: tahir@cancer.dk. 2. Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen Ø, Denmark. 3. Department of Environmental Science, Aarhus University, Frederiksborgvej 399, P.O. Box. 358, DK-4000 Roskilde, Denmark; Global Centre for Clean Air Research (GCARE), Department of Civil and Environmental Engineering, University of Surrey, Guildford GU2 7XH, UK. 4. Department of Environmental Science, Aarhus University, Frederiksborgvej 399, P.O. Box. 358, DK-4000 Roskilde, Denmark. 5. Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen Ø, Denmark; Institute for Applied Environmental Health, School of Public Health, University of Maryland, College Park, MD, USA. 6. Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen Ø, Denmark; Department of Natural Science and Environment, Roskilde University, Roskilde, Denmark. 7. Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen Ø, Denmark; Department of Environmental Science, Aarhus University, Frederiksborgvej 399, P.O. Box. 358, DK-4000 Roskilde, Denmark.
Abstract
BACKGROUND: Leukemia is one of the most common forms of hematologic malignancy, which can affect people of all ages. We previously showed an association between exposure to ambient particulate matter 2.5 μg (PM2.5) and risk for leukemia in adults. The aim of this study was to investigate which PM2.5 constituents were responsible for our previous observation. METHODS: This is a nationwide register-based case-control study. We identified 14,983 persons diagnosed with leukemia at age 20 or above, 1989-2014, in the Danish Cancer Registry. We selected up to four sex and age-matched controls per case at random from the entire Danish population (n = 51,613). We modelled concentrations of ambient PM2.5 and its constituents at the addresses of cases and controls for the 10-year period before index date with a state-of-the-art multiscale air pollution modeling system. We used conditional logistic regression to estimate odds ratios (ORs) adjusted for individual and neighborhood level socio-demographic variables. RESULT: The results showed higher risk for overall leukemia in association with interquartile range exposure to PM2.5 (OR = 1.09; 95% CI: 1.02, 1.17), black carbon (BC) (OR = 1.02; 95% CI: 1.00, 1.03), secondary inorganic aerosols (SIA) (OR = 1.15; 95% CI: 1.03, 1.29) and its components ammonium (NH4) (OR = 1.08; 95% CI: 1.00, 1.17) and nitrate (NO3) (OR = 1.08; 95% CI: 1.02, 1.14). In leukemia subtype analysis, statistically significant associations were found for AML with PM2.5 (OR = 1.14; 95% CI: 1.00, 1.29), BC (OR = 1.03; 95% CI: 1.00, 1.07), SIA (OR = 1.23; 95% CI: 1.01, 1.51), NH4 (OR = 1.16; 95% CI: 1.01, 1.34) and NO3 (OR = 1.12; 95% CI: 1.01, 1.24). The association between PM2.5 and leukemia persisted in two pollutants models including sum of primary emitted black and organic carbon (BC + OC), secondary organic aerosols (SOA), or sea-salt. The association between black carbon (BC) and leukemia persisted in two pollutants models including organic carbon (OC). The three pollutant model with sulfate (SO4), NH4 and NO3 showed an association with NO3 but not with SO4 or NH4. CONCLUSION: Ambient concentrations of the PM2.5 components BC, NH4 and NO3 at the residence showed associations with risk of incident leukemia in adults.
BACKGROUND:Leukemia is one of the most common forms of hematologic malignancy, which can affect people of all ages. We previously showed an association between exposure to ambient particulate matter 2.5 μg (PM2.5) and risk for leukemia in adults. The aim of this study was to investigate which PM2.5 constituents were responsible for our previous observation. METHODS: This is a nationwide register-based case-control study. We identified 14,983 persons diagnosed with leukemia at age 20 or above, 1989-2014, in the Danish Cancer Registry. We selected up to four sex and age-matched controls per case at random from the entire Danish population (n = 51,613). We modelled concentrations of ambient PM2.5 and its constituents at the addresses of cases and controls for the 10-year period before index date with a state-of-the-art multiscale air pollution modeling system. We used conditional logistic regression to estimate odds ratios (ORs) adjusted for individual and neighborhood level socio-demographic variables. RESULT: The results showed higher risk for overall leukemia in association with interquartile range exposure to PM2.5 (OR = 1.09; 95% CI: 1.02, 1.17), black carbon (BC) (OR = 1.02; 95% CI: 1.00, 1.03), secondary inorganic aerosols (SIA) (OR = 1.15; 95% CI: 1.03, 1.29) and its components ammonium (NH4) (OR = 1.08; 95% CI: 1.00, 1.17) and nitrate (NO3) (OR = 1.08; 95% CI: 1.02, 1.14). In leukemia subtype analysis, statistically significant associations were found for AML with PM2.5 (OR = 1.14; 95% CI: 1.00, 1.29), BC (OR = 1.03; 95% CI: 1.00, 1.07), SIA (OR = 1.23; 95% CI: 1.01, 1.51), NH4 (OR = 1.16; 95% CI: 1.01, 1.34) and NO3 (OR = 1.12; 95% CI: 1.01, 1.24). The association between PM2.5 and leukemia persisted in two pollutants models including sum of primary emitted black and organic carbon (BC + OC), secondary organic aerosols (SOA), or sea-salt. The association between black carbon (BC) and leukemia persisted in two pollutants models including organic carbon (OC). The three pollutant model with sulfate (SO4), NH4 and NO3 showed an association with NO3 but not with SO4 or NH4. CONCLUSION: Ambient concentrations of the PM2.5 components BC, NH4 and NO3 at the residence showed associations with risk of incident leukemia in adults.