title: Application of the double kernel density approach to the analysis of cancer incidence in a major metropolitan area.
abstract: BACKGROUND
  Although cancer is a main cause of human morbidity worldwide, relatively small numbers of new cancer cases are recorded annually in single urban areas. This makes the association between cancer morbidity and environmental risk factors, such as ambient air pollution, difficult to detect using traditional methods of analysis based on age standardized rates and zonal estimates.
  
  
  OBJECTIVE
  The present study investigates the association between air pollution and cancer morbidity in the Greater Haifa Metropolitan Area in Israel by comparing two analytical techniques: the traditional zonal approach and more recently developed Double Kernel Density (DKD) tools. While the first approach uses age adjusted Standardized Incidence Ratios (SIRs) for small census areas, the second approach estimates the areal density of cancer cases, normalized by the areal density of background population in which cancer events occurred. Both analyses control for several potential confounders, including air pollution, proximities to main industrial facilities and socio-demographic attributes.
  
  
  RESULTS
  Air pollution variables and distances to industrial facilities emerged as statistically significant predictors of lung and NHL cancer morbidity in the DKD-based models (p<0.05) but not in the models based on SIRs estimates (p>0.2).
  
  
  CONCLUSIONS
  DKD models appear to be a more sensitive tool for assessing potential environmental risks than traditional SIR-based models, because DKD estimates do not depend on a priory geographic delineations of statistical zones and produce a smooth and continuous disease 'risk surface' covering the entire study area. We suggest using the DKD method in similar studies of the effect of ambient air pollution on chronic morbidity, especially in cases in which the number of statistical areas available for aggregation and comparison is small and recorded morbidity events are relatively rare.
authors.affiliation: Department of Natural Resources & Environmental Management, Faculty of Management, University of Haifa, Mt. Carmel, Haifa 3498838, Israel.
authors.forename: Sarit
authors.initials: S
authors.lastname: Davarashvili
authors.affiliation: Department of Natural Resources & Environmental Management, Faculty of Management, University of Haifa, Mt. Carmel, Haifa 3498838, Israel.
authors.forename: Marina
authors.initials: M
authors.lastname: Zusman
authors.affiliation: Israel Center for Disease Control, Israel; School of Public Health, University of Haifa, Israel.
authors.forename: Lital
authors.initials: L
authors.lastname: Keinan-Boker
authors.affiliation: Department of Natural Resources & Environmental Management, Faculty of Management, University of Haifa, Mt. Carmel, Haifa 3498838, Israel.
authors.forename: Natalya
authors.initials: N
authors.lastname: Rybnikova
authors.affiliation: Israel Center for Disease Control, Israel.
authors.forename: Zalman
authors.initials: Z
authors.lastname: Kaufman
authors.affiliation: Israel Center for Disease Control, Israel.
authors.forename: Barbara G
authors.initials: BG
authors.lastname: Silverman
authors.affiliation: School of Public Health, University of Haifa, Israel.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Dubnov
authors.affiliation: School of Public Health, University of Haifa, Israel.
authors.forename: Shai
authors.initials: S
authors.lastname: Linn
authors.affiliation: Department of Natural Resources & Environmental Management, Faculty of Management, University of Haifa, Mt. Carmel, Haifa 3498838, Israel. Electronic address: portnov@research.haifa.ac.il.
authors.forename: Boris A
authors.initials: BA
authors.lastname: Portnov
mesh_terms: D000393:Air Pollutants; D000397:Air Pollution / Q000009:adverse effects*; D002947:Cities / Q000453:epidemiology; D004781:Environmental Exposure; D005843:Geography; D006801:Humans; D015994:Incidence; D007557:Israel / Q000453:epidemiology; D009017:Morbidity; D009369:Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D018570:Risk Assessment / Q000379:methods*; D018709:Statistics, Nonparametric
chemical_list: D000393:Air Pollutants
keywords: Air pollution, industrial proximity; Double Kernel Density (DKD) approach; Greater Haifa Metropolitan Area (GHMA); Israel; Lung cancer; Non-Hodgkin lymphoma (NHL); Standardized Incidence Ratios (SIRs)