title: Impact of fetal and childhood mercury exposure on immune status in children.
abstract: BACKGROUND
  Mercury exposure have been shown to affect immune status in animals as reflected by cytokine expression. It is unclear whether low levels of exposure during fetal and/or childhood periods could impact on immune status in humans.
  
  
  OBJECTIVE
  To test the hypothesis that fetal and childhood mercury exposure is associated with childhood cytokine profiles and to investigate whether childhood selenium levels interact with any of the associations found.
  
  
  METHODS
  Children were recruited from a previously established birth cohort between the ages of 6-9 years for assessment and measurement of blood mercury, selenium and cytokine profile (interleukin (IL)-4, IL-6, IL-8, IL-10, IL-13 and TNF-alpha). Multivariable linear regression models were used to assess the adjusted association of cord blood mercury concentration and current mercury concentrations with levels of the cytokine levels. We tested whether the association with current mercury level varied by current selenium level and cord blood mercury level.
  
  
  RESULTS
  IL-10 was negatively associated with current blood mercury concentration. The effect was greatest in cases with low cord blood mercury and low current selenium concentrations. None of the other cytokine levels were associated with either cord blood or current blood mercury concentrations, except that cord blood mercury was negatively associated with IL-6.
  
  
  CONCLUSIONS
  Childhood mercury exposure was negatively associated with childhood IL-10 levels. It is postulated that while selenium is protective, low levels of fetal mercury exposure may increase the degree of this negative association during childhood. Further studies into the clinical significance of these findings are required.
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Lai Ling
authors.initials: LL
authors.lastname: Hui
authors.affiliation: Department of Chemical Pathology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Michael Ho Ming
authors.initials: MHM
authors.lastname: Chan
authors.affiliation: Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong. Electronic address: hshslam@cuhk.edu.hk.
authors.forename: Hugh Simon
authors.initials: HS
authors.lastname: Lam
authors.affiliation: Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Peggy Hiu Ying
authors.initials: PHY
authors.lastname: Chan
authors.affiliation: Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Ka Ming
authors.initials: KM
authors.lastname: Kwok
authors.affiliation: Department of Chemical Pathology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Iris Hiu Shuen
authors.initials: IHS
authors.lastname: Chan
authors.affiliation: Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Albert Martin
authors.initials: AM
authors.lastname: Li
authors.affiliation: Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Tai Fai
authors.initials: TF
authors.lastname: Fok
mesh_terms: D002648:Child; D016207:Cytokines / Q000097:blood*; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000097:blood*; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005333:Fetus; D006801:Humans; D008297:Male; D008628:Mercury / Q000097:blood*; D011247:Pregnancy; D012643:Selenium / Q000097:blood
chemical_list: D016207:Cytokines; D004785:Environmental Pollutants; D008628:Mercury; D012643:Selenium
keywords: Children; Cord blood; Cytokines; Mercury; Selenium