title: Interactions between cigarette smoking and ambient PM2.5for cardiovascular mortality.
abstract: Associations between long-term exposure to ambient fine particulate matter (PM2.5) and all-cause and cardiovascular mortality are well documented however less is known regarding possible interactions with cigarette smoking. We previously reported a supra-additive synergistic relationship between PM2.5and cigarette smoking for lung cancer mortality. Here we examine interactions for all-cause and cardiovascular mortality among 429,406 current or never smoking participants in the prospective American Cancer Society Cancer Prevention Study-II with modeled PM2.5concentrations. Cox proportional and additive hazards models were used to estimate mortality associations and interactions on the multiplicative and additive scales. A total of 146,495 all-cause and 64,339 cardiovascular (plus diabetes) deaths were observed. The hazard ratio (HR) (95% confidence interval (CI)) for cardiovascular mortality for high vs. low PM2.5exposure (>14.44µg/m3vs ≤10.59µg/m3, 75th vs 25th percentile) was 1.09 (95% CI 1.05, 1.12) in never smokers. The HR for cigarette smoking was 1.89 (95% CI 1.82, 1.96) in those with low PM2.5. The HR for both high PM2.5and cigarette smoking was 2.08 (95% CI 2.00, 2.17). A small significant excess relative risk due to interaction (0.10; 95% CI 0.02, 0.19) was observed. Quantification of the public health burden attributed to the interaction between PM2.5and cigarette smoking indicated a total of 32 (95% CI -6, 71) additional cardiovascular deaths per 100,000 person-years due to this interaction. In conclusion, PM2.5was associated with all-cause and cardiovascular mortality in both smokers and never smokers, with some evidence for a small additive interaction with cigarette smoking. Reductions in cigarette smoking will result in the greatest impact on reducing all-cause and cardiovascular death at the levels of PM2.5observed in this study. However, reductions in PM2.5will also contribute to preventing a proportion of mortality attributed to cigarette smoking.
authors.affiliation: McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Canada; Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain. Electronic address: mturner@uottawa.ca.
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Turner
authors.affiliation: Health Effects Institute, Boston, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Cohen
authors.affiliation: Population Studies Division, Health Canada, Ottawa, Canada.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Burnett
authors.affiliation: Division of Environmental Health Sciences, School of Public Health, University of California Berkeley, Berkeley, USA; Department of Environmental Health Science, Fielding School of Public Health, University of California, Los Angeles, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Jerrett
authors.affiliation: Epidemiology Research Program, American Cancer Society, Atlanta, GA, USA.
authors.forename: W Ryan
authors.initials: WR
authors.lastname: Diver
authors.affiliation: Epidemiology Research Program, American Cancer Society, Atlanta, GA, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Gapstur
authors.affiliation: McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Canada; School of Epidemiology, Public Health and Disease Prevention, Faculty of Medicine, University of Ottawa, Ottawa, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Krewski
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, USC Institute for Global Health, University of Southern California, Los Angeles, USA.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Samet
authors.affiliation: Department of Economics, Brigham Young University, Provo, USA.
authors.forename: C Arden
authors.initials: CA
authors.lastname: Pope
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology* / Q000401:mortality*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D052638:Particulate Matter / Q000009:adverse effects*; D011446:Prospective Studies; D012907:Smoking / Q000009:adverse effects*; D014481:United States / Q000453:epidemiology
chemical_list: D052638:Particulate Matter
keywords: Additive interaction; Air pollution; Cardiovascular mortality; Cigarette smoking; Particulate matter