title: Mercury Exposure and Antinuclear Antibodies among Females of Reproductive Age in the United States: NHANES.
abstract: BACKGROUND
  Immune dysregulation associated with mercury has been suggested, although data in the general population are lacking. Chronic exposure to low levels of methylmercury (organic) and inorganic mercury is common, such as through fish consumption and dental amalgams.
  
  
  OBJECTIVE
  We examined associations between mercury biomarkers and antinuclear antibody (ANA) positivity and titer strength.
  
  
  METHODS
  Among females 16-49 years of age (n = 1,352) from the National Health and Nutrition Examination Survey (NHANES) 1999-2004, we examined cross-sectional associations between mercury and ANAs (indirect immunofluorescence; cutoff ≥ 1:80). Three biomarkers of mercury exposure were used: hair (available 1999-2000) and total blood (1999-2004) predominantly represented methylmercury, and urine (1999-2002) represented inorganic mercury. Survey statistics were used. Multivariable modeling adjusted for several covariates, including age and omega-3 fatty acids.
  
  
  RESULTS
  Sixteen percent of females were ANA positive; 96% of ANA positives had a nuclear speckled staining pattern. Geometric mean (geometric SD) mercury concentrations were 0.22 (0.03) ppm in hair, 0.92 (0.05) μg/L blood, and 0.62 (0.04) μg/L urine. Hair and blood, but not urinary, mercury were associated with ANA positivity (sample sizes 452, 1,352, and 804, respectively), after adjusting for confounders: for hair, odds ratio (OR) = 4.10 (95% CI: 1.66, 10.13); for blood, OR = 2.32 (95% CI: 1.07, 5.03) comparing highest versus lowest quantiles. Magnitudes of association were strongest for high-titer (≥ 1:1,280) ANA: hair, OR = 11.41 (95% CI: 1.60, 81.23); blood, OR = 5.93 (95% CI: 1.57, 22.47).
  
  
  CONCLUSIONS
  Methylmercury, at low levels generally considered safe, was associated with subclinical autoimmunity among reproductive-age females. Autoantibodies may predate clinical disease by years; thus, methylmercury exposure may be relevant to future autoimmune disease risk.
authors: Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA.
authors: Emily C
authors: EC
authors: Somers
authors: Martha A
authors: MA
authors: Ganser
authors: Jeffrey S
authors: JS
authors: Warren
authors: Niladri
authors: N
authors: Basu
authors: Lu
authors: L
authors: Wang
authors: Suzanna M
authors: SM
authors: Zick
authors: Sung Kyun
authors: SK
authors: Park
mesh_terms: D000293:Adolescent; D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood*; D000954:Antigens, Surface / Q000097:blood; D015415:Biomarkers / Q000097:blood / Q000378:metabolism / Q000652:urine; D003430:Cross-Sectional Studies; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000097:blood / Q000378:metabolism* / Q000652:urine; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006197:Hair / Q000737:chemistry; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008628:Mercury / Q000097:blood / Q000378:metabolism / Q000652:urine; D017669:Mercury Compounds / Q000652:urine*; D008767:Methylmercury Compounds / Q000097:blood / Q000378:metabolism*; D008875:Middle Aged; D009749:Nutrition Surveys; D014481:United States; D055815:Young Adult
chemical_list: D000974:Antibodies, Antinuclear; D000954:Antigens, Surface; D015415:Biomarkers; D004785:Environmental Pollutants; D007074:Immunoglobulin G; D017669:Mercury Compounds; D008767:Methylmercury Compounds; D008628:Mercury