title: Total blood mercury and serum measles antibodies in US children, NHANES 2003-2004.
abstract: BACKGROUND
  Environmental toxins, pathogens and host susceptibility cofactors may interact to contribute to disease. In vitro mercury exposure inhibited antiviral cytokines in human cells; however, little is known about the relationship between mercury and viruses in children. Children are susceptible to mercury toxicity; lower vitamin B-12 and folate levels and higher homocysteine levels may represent susceptibility cofactors. This study aimed to evaluate associations between total blood mercury (Hg) and measles antibodies in children, and the influence of these susceptibility cofactors.
  
  
  METHODS
  Cross-sectional data on serum measles antibodies, Hg, homocysteine, methylmalonic acid (MMA, indicator of B-12 deficiency), and folate were obtained from the 2003-2004 NHANES for children aged 6-11 years with measles seropositivity (n=692). We used linear regression to evaluate relationships between measles antibodies and Hg, stratified by sex, MMA ≥, folate <, and homocysteine≥sample medians, adjusted for demographic, nutritional and environmental cofactors.
  
  
  RESULTS
  Hg (range: 0.10-19.10μg/L) was inversely associated with measles antibodies (range: 1.00-28.24 units) in non-stratified analysis (n=692), yet positively associated among the subset of boys with higher MMA and lower folate (n=98). Among this subset with higher homocysteine levels (n=61), correlations were positive across all Hg quartiles relative to Q1 (Hg≤0.20μg/L): Q2:β=6.60 (3.02, 10.19); Q3:β=8.49 (6.17, 10.81); Q4 (Hg>0.80μg/L):β=4.90 (2.12, 7.67) (p(trend)=0.077).
  
  
  CONCLUSIONS
  Stratification by susceptibility cofactors revealed opposing directionality for correlations between Hg and measles antibodies, with positive effect estimates at lowest exposures only among boys with higher MMA, lower folate and higher homocysteine levels.
authors: Stony Brook University, School of Medicine, Health Sciences Center Level 3, Room 071, Stony Brook, NY 11794-8338, USA. 2crgallagher@optonline.net
authors: Carolyn M
authors: CM
authors: Gallagher
authors: Dylan M
authors: DM
authors: Smith
authors: Jaymie R
authors: JR
authors: Meliker
mesh_terms: D000914:Antibodies, Viral / Q000097:blood*; D002648:Child; D003430:Cross-Sectional Studies; D004781:Environmental Exposure / Q000706:statistics & numerical data; D004785:Environmental Pollutants / Q000097:blood*; D005260:Female; D005492:Folic Acid / Q000097:blood; D006710:Homocysteine / Q000097:blood; D006801:Humans; D016014:Linear Models; D008297:Male; D008457:Measles / Q000097:blood* / Q000453:epidemiology; D008459:Measles virus / Q000276:immunology*; D008628:Mercury / Q000097:blood*; D008764:Methylmalonic Acid / Q000097:blood; D009749:Nutrition Surveys; D014481:United States / Q000453:epidemiology
chemical_list: D000914:Antibodies, Viral; D004785:Environmental Pollutants; D006710:Homocysteine; D008764:Methylmalonic Acid; D005492:Folic Acid; D008628:Mercury