title: A time-series study of the health effects of water-soluble and total-extractable metal content of airborne particulate matter.
abstract: OBJECTIVE
  To assess whether adverse acute cardiopulmonary health outcomes are associated with concentration of trace metals in airborne particulate matter.
  
  
  METHODS
  Daily PM(10) and PM(2.5) were collected for 1 year in Edinburgh, UK, and the water-soluble and total-extractable content of 11 trace metals determined in each sample. Time series were analysed using generalised additive Poisson regression models, including adjustment for minimum temperature and less smoothing of trends. Methods were explored of extending the time series of metal concentration in daily PM(10) for the previous 7 years using multiple regression of the variation in metal content for the 1 year of measurements and the associated variation in air mass source region and other concurrently-measured potential predictor variables.
  
  
  RESULTS
  The 1 year of direct measurements showed no evidence of significant associations of particle-bound metal concentration with health outcomes beyond that expected by chance. Analysis of the extended time series showed significant positive associations with cardiovascular admissions both for total PM(10) and for a number of the metals (eg, Cu, Fe, Ni, V, Zn) but the metal effects were no longer significant after adjusting for PM(10).
  
  
  CONCLUSIONS
  Within the limitations of the study power, the epidemiological results have not provided evidence for associations between particle-bound metal concentrations and adverse health outcomes that are substantially greater than for total PM. The generally strong correlations between metal and total PM suggest that quantifying independent effects of PM metal exposure on health will be difficult, even using more powerful time series of direct measurements.
authors.affiliation: School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, UK. m.heal@ed.ac.uk
authors.forename: M R
authors.initials: MR
authors.lastname: Heal
authors.forename: R A
authors.initials: RA
authors.lastname: Elton
authors.forename: L R
authors.initials: LR
authors.lastname: Hibbs
authors.forename: R M
authors.initials: RM
authors.lastname: Agius
authors.forename: I J
authors.initials: IJ
authors.lastname: Beverland
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects / Q000032:analysis*; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology*; D004781:Environmental Exposure / Q000009:adverse effects / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D062665:Epidemiological Monitoring; D006801:Humans; D008670:Metals / Q000009:adverse effects / Q000032:analysis*; D052638:Particulate Matter / Q000009:adverse effects / Q000032:analysis*; D012120:Respiration Disorders / Q000453:epidemiology / Q000209:etiology*; D012606:Scotland / Q000453:epidemiology; D012995:Solubility; D014867:Water
chemical_list: D000393:Air Pollutants; D008670:Metals; D052638:Particulate Matter; D014867:Water