title: Occupational trichloroethylene exposure and kidney cancer: a meta-analysis.
abstract: BACKGROUND
  We conducted a meta-analysis of occupational studies of trichloroethylene-exposed workers to evaluate patterns of associations by study design, exposure assessment methods, and occupational groups.
  
  
  METHODS
  Estimates of summary relative risk (RR) were calculated using inverse-variance weighting methods. Cohort studies were classified as group I or group II, depending on quality of the study design and exposure assessment procedures. We conducted sensitivity analyses to examine sources of heterogeneity.
  
  
  RESULTS
  Across all studies meeting our inclusion criteria (n = 23), the summary RR was 1.42 (95% confidence interval = 1.17-1.77), with heterogeneity present (test for heterogeneity: P = 0.001). After removal of 3 outlier studies, the summary RR for the remaining studies was 1.24 (1.06-1.45 (test for heterogeneity: P = 0.616)). The summary RR for studies of workers who were identified as more likely exposed to trichloroethylene (group I studies) was 1.34 (1.06-1.68). With outlier studies removed, the group II summary RR estimates for the cohort studies was 0.88 (0.58-1.33) and for the case-control studies was 1.33 (1.02-1.73). The summary RR for studies that used biomarkers to classify exposure (n = 3) was 1.02 (0.59-1.77) and for studies of aerospace/aircraft workers (n = 7) was 1.14 (0.84-1.57).
  
  
  CONCLUSIONS
  Positive associations were observed across various study groups. However, considerations of unmeasured potential confounding, lack of quantitative exposure assessment and lack of exposure-response patterns limit epidemiologic insight into the role of trichloroethylene exposure and its potential causal association with kidney cancer.
authors.affiliation: Health Science Practice, Exponent, Inc, Menlo Park, CA 94025, USA. mkelsh@exponent.com
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kelsh
authors.forename: Dominik D
authors.initials: DD
authors.lastname: Alexander
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Mink
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Mandel
mesh_terms: D015986:Confounding Factors, Epidemiologic; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D008297:Male; D016273:Occupational Exposure / Q000009:adverse effects*; D018570:Risk Assessment; D014241:Trichloroethylene / Q000009:adverse effects*
chemical_list: D014241:Trichloroethylene