title: Mercury levels in newborns and infants after receipt of thimerosal-containing vaccines.
abstract: OBJECTIVE
  Thimerosal is a mercurial preservative that was widely used in multidose vaccine vials in the United States and Europe until 2001 and continues to be used in many countries throughout the world. We conducted a pharmacokinetic study to assess blood levels and elimination of ethyl mercury after vaccination of infants with thimerosal-containing vaccines.
  
  
  METHODS
  Blood, stool, and urine samples were obtained before vaccination and 12 hours to 30 days after vaccination from 216 healthy children: 72 newborns (group 1), 72 infants aged 2 months (group 2), and 72 infants aged 6 months (group 3). Total mercury levels were measured by atomic absorption. Blood mercury pharmacokinetics were calculated by pooling the data on the group and were based on a 1-compartment first-order pharmacokinetics model.
  
  
  RESULTS
  For groups 1, 2, and 3, respectively, (1) mean +/- SD weights were 3.4 +/- 0.4, 5.1 +/- 0.6, and 7.7 +/- 1.1 kg; (2) maximal mean +/- SD blood mercury levels were 5.0 +/- 1.3, 3.6 +/- 1.5, and 2.8 +/- 0.9 ng/mL occurring at 0.5 to 1 day after vaccination; (3) maximal mean +/- SD stool mercury levels were 19.1 +/- 11.8, 37.0 +/- 27.4, and 44.3 +/- 23.9 ng/g occurring on day 5 after vaccination for all groups; and (4) urine mercury levels were mostly nondetectable. The blood mercury half-life was calculated to be 3.7 days and returned to prevaccination levels by day 30.
  
  
  CONCLUSIONS
  The blood half-life of intramuscular ethyl mercury from thimerosal in vaccines in infants is substantially shorter than that of oral methyl mercury in adults. Increased mercury levels were detected in stools after vaccination, suggesting that the gastrointestinal tract is involved in ethyl mercury elimination. Because of the differing pharmacokinetics of ethyl and methyl mercury, exposure guidelines based on oral methyl mercury in adults may not be accurate for risk assessments in children who receive thimerosal-containing vaccines.
authors.affiliation: Department of Microbiology/Immunology, Pediatrics, and Medicine, University of Rochester, Rochester, New York 14642, USA. michael_pichichero@urmc.rochester.edu
authors.forename: Michael E
authors.initials: ME
authors.lastname: Pichichero
authors.forename: Angela
authors.initials: A
authors.lastname: Gentile
authors.forename: Norberto
authors.initials: N
authors.lastname: Giglio
authors.forename: Veronica
authors.initials: V
authors.lastname: Umido
authors.forename: Thomas
authors.initials: T
authors.lastname: Clarkson
authors.forename: Elsa
authors.initials: E
authors.lastname: Cernichiari
authors.forename: Grazyna
authors.initials: G
authors.lastname: Zareba
authors.forename: Carlos
authors.initials: C
authors.lastname: Gotelli
authors.forename: Mariano
authors.initials: M
authors.lastname: Gotelli
authors.forename: Lihan
authors.initials: L
authors.lastname: Yan
authors.forename: John
authors.initials: J
authors.lastname: Treanor
mesh_terms: D001500:BCG Vaccine / Q000493:pharmacokinetics; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000493:pharmacokinetics; D005035:Ethylmercury Compounds / Q000493:pharmacokinetics; D005243:Feces / Q000737:chemistry; D005260:Female; D006207:Half-Life; D017325:Hepatitis B Vaccines / Q000493:pharmacokinetics; D006801:Humans; D007223:Infant; D007231:Infant, Newborn / Q000097:blood* / Q000378:metabolism; D007273:Injections, Intramuscular; D008297:Male; D008628:Mercury / Q000032:analysis / Q000097:blood* / Q000652:urine; D011310:Preservatives, Pharmaceutical / Q000493:pharmacokinetics*; D013849:Thimerosal / Q000493:pharmacokinetics*; D014612:Vaccines / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D001500:BCG Vaccine; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D005035:Ethylmercury Compounds; D017325:Hepatitis B Vaccines; D011310:Preservatives, Pharmaceutical; D014612:Vaccines; D013849:Thimerosal; D008628:Mercury