title: Evidence on the human health effects of low-level methylmercury exposure.
abstract: BACKGROUND
  Methylmercury (MeHg) is a known neuro-toxicant. Emerging evidence indicates it may have adverse effects on the neuro-logic and other body systems at common low levels of exposure. Impacts of MeHg exposure could vary by individual susceptibility or be confounded by beneficial nutrients in fish containing MeHg. Despite its global relevance, synthesis of the available literature on low-level MeHg exposure has been limited.
  
  
  OBJECTIVE
  We undertook a synthesis of the current knowledge on the human health effects of low-level MeHg exposure to provide a basis for future research efforts, risk assessment, and exposure remediation policies worldwide.
  
  
  METHODS
  We reviewed the published literature for original human epidemiologic research articles that reported a direct biomarker of mercury exposure. To focus on high-quality studies and those specifically on low mercury exposure, we excluded case series, as well as studies of populations with unusually high fish consumption (e.g., the Seychelles), marine mammal consumption (e.g., the Faroe Islands, circumpolar, and other indigenous populations), or consumption of highly contaminated fish (e.g., gold-mining regions in the Amazon).
  
  
  RESULTS
  Recent evidence raises the possibility of effects of low-level MeHg exposure on fetal growth among susceptible subgroups and on infant growth in the first 2 years of life. Low-level effects of MeHg on neuro-logic outcomes may differ by age, sex, and timing of exposure. No clear pattern has been observed for cardio-vascular disease (CVD) risk across populations or for specific CVD end points. For the few studies evaluating immunologic effects associated with MeHg, results have been inconsistent.
  
  
  CONCLUSIONS
  Studies targeted at identifying potential mechanisms of low-level MeHg effects and characterizing individual susceptibility, sexual dimorphism, and non-linearity in dose response would help guide future prevention, policy, and regulatory efforts surrounding MeHg exposure.
authors.affiliation: Section of Biostatistics and Epidemiology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA. margaret.r.karagas@dartmouth.edu
authors.forename: Margaret R
authors.initials: MR
authors.lastname: Karagas
authors.forename: Anna L
authors.initials: AL
authors.lastname: Choi
authors.forename: Emily
authors.initials: E
authors.lastname: Oken
authors.forename: Milena
authors.initials: M
authors.lastname: Horvat
authors.forename: Rita
authors.initials: R
authors.lastname: Schoeny
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Kamai
authors.forename: Whitney
authors.initials: W
authors.lastname: Cowell
authors.forename: Philippe
authors.initials: P
authors.lastname: Grandjean
authors.forename: Susan
authors.initials: S
authors.lastname: Korrick
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000139:chemically induced*; D002648:Child; D002657:Child Development / Q000187:drug effects*; D004781:Environmental Exposure; D016021:Epidemiologic Studies; D047109:Fetal Development / Q000187:drug effects*; D005399:Fishes / Q000378:metabolism*; D006801:Humans; D007107:Immune System / Q000187:drug effects*; D007223:Infant; D008767:Methylmercury Compounds / Q000633:toxicity*; D009420:Nervous System / Q000187:drug effects*
chemical_list: D015415:Biomarkers; D008767:Methylmercury Compounds