title: Mercury exposure and risk of cardiovascular disease in two U.S. cohorts.
abstract: BACKGROUND
  Exposure to methylmercury from fish consumption has been linked to a potentially increased risk of cardiovascular disease, but evidence from prior studies is equivocal. Beneficial effects of the ingestion of fish and selenium may also modify such effects.
  
  
  METHODS
  Among subjects from two U.S. cohorts (a total of 51,529 men and 121,700 women) whose toenail clippings had been stored, we prospectively identified incident cases of cardiovascular disease (coronary heart disease and stroke) in 3427 participants and matched them to risk-set-sampled controls according to age, sex, race, and smoking status. Toenail mercury and selenium concentrations were assessed with the use of neutron-activation analysis. Other demographic characteristics, cardiovascular risk factors, fish consumption, and lifestyle habits were assessed by means of validated questionnaires. Associations between mercury exposure and incident cardiovascular disease were evaluated with the use of conditional logistic regression.
  
  
  RESULTS
  Median toenail mercury concentrations were 0.23 μg per gram (interdecile range, 0.06 to 0.94) in the case participants and 0.25 μg per gram (interdecile range, 0.07 to 0.97) in the controls. In multivariate analyses, participants with higher mercury exposures did not have a higher risk of cardiovascular disease. For comparisons of the fifth quintile of mercury exposure with the first quintile, the relative risks were as follows: coronary heart disease, 0.85 (95% confidence interval [CI], 0.69 to 1.04; P=0.10 for trend); stroke, 0.84 (95% CI, 0.62 to 1.14; P=0.27 for trend); and total cardiovascular disease, 0.85 (95% CI, 0.72 to 1.01; P=0.06 for trend). Findings were similar in analyses of participants with low selenium concentrations or low overall fish consumption and in several additional sensitivity analyses.
  
  
  CONCLUSIONS
  We found no evidence of any clinically relevant adverse effects of mercury exposure on coronary heart disease, stroke, or total cardiovascular disease in U.S. adults at the exposure levels seen in this study. (Funded by the National Institutes of Health.).
authors.affiliation: Division of Cardiovascular Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA. dmozaffa@hsph.harvard.edu
authors.forename: Dariush
authors.initials: D
authors.lastname: Mozaffarian
authors.forename: Peilin
authors.initials: P
authors.lastname: Shi
authors.forename: J Steven
authors.initials: JS
authors.lastname: Morris
authors.forename: Donna
authors.initials: D
authors.lastname: Spiegelman
authors.forename: Philippe
authors.initials: P
authors.lastname: Grandjean
authors.forename: David S
authors.initials: DS
authors.lastname: Siscovick
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
authors.forename: Eric B
authors.initials: EB
authors.lastname: Rimm
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002318:Cardiovascular Diseases / Q000453:epidemiology*; D016022:Case-Control Studies; D015331:Cohort Studies; D004032:Diet; D015987:Effect Modifier, Epidemiologic; D004781:Environmental Exposure / Q000009:adverse effects / Q000032:analysis*; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage; D005260:Female; D005399:Fishes; D005506:Food Contamination; D006801:Humans; D016015:Logistic Models; D008297:Male; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000009:adverse effects* / Q000032:analysis; D008875:Middle Aged; D015999:Multivariate Analysis; D009262:Nails / Q000737:chemistry*; D012307:Risk Factors; D017747:Seafood; D012643:Selenium / Q000032:analysis*; D014481:United States / Q000453:epidemiology
chemical_list: D015415:Biomarkers; D015525:Fatty Acids, Omega-3; D008767:Methylmercury Compounds; D008628:Mercury; D012643:Selenium