title: Risk of ischemic heart disease following occupational exposure to welding fumes: a systematic review with meta-analysis.
abstract: OBJECTIVE
  Air pollution has been linked to an increased risk of ischemic heart disease (IHD), but less is known about occupational exposure to welding fumes and the risk of IHD. The objective of this paper was to review the epidemiological evidence on causal links between welding fume exposure and risk of IHD and to investigate whether the risk of IHD depends on specific welding characteristics.
  
  
  METHODS
  A systematic search in Medline 1979-2013 and EMBASE 1974-2013 identified 18 epidemiological studies with at least one risk estimate of IHD morbidity or mortality among workers exposed to welding fumes. Following an assessment of completeness of reporting, confounding, and bias, each risk estimate was characterized as more or less reliable. Pooled risk estimates were computed across studies by random effect meta-analyses.
  
  
  RESULTS
  The weighted relative risk (RR) for IHD following exposure to welding fumes was 1.09 [95 % confidence interval (CI) 1.00, 1.19]. We calculated a RR of 1.39 (95 % CI 0.96, 2.02) among studies using an internal reference group and 1.08 (95 % CI 0.99, 1.18) for studies using an external reference group. An increased risk was observed for acute myocardial infarction RR = 1.69 (95 % CI 1.18, 2.42) and other IHDs RR = 1.06 (95 % CI 0.98, 1.14). There was too limited evidence to evaluate the risk of IHD related to specific welding characteristics.
  
  
  CONCLUSIONS
  Several studies indicate that welding is associated with a moderately increased risk of IHD; however, bias and confounding cannot be ruled out with reasonable confidence.
authors.affiliation: Department of Occupational and Environmental Medicine, Bispebjerg University Hospital, Bispebjerg Bakke 23, Opgang 33, 2400, Copenhagen NV, Denmark, emina.mocevic.01@regionh.dk.
authors.forename: Emina
authors.initials: E
authors.lastname: Mocevic
authors.forename: Pernille
authors.initials: P
authors.lastname: Kristiansen
authors.forename: Jens Peter
authors.initials: JP
authors.lastname: Bonde
mesh_terms: D000395:Air Pollutants, Occupational / Q000009:adverse effects*; D015331:Cohort Studies; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects; D017202:Myocardial Ischemia / Q000453:epidemiology* / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D012307:Risk Factors; D014896:Welding
chemical_list: D000395:Air Pollutants, Occupational