Effect of hemoglobin adjustment on the precision of mercury concentrations in maternal and cord blood.
The cord-blood mercury concentration is usually considered the best biomarker in regard to developmental methylmercury neurotoxicity. However, the mercury concentration may be affected by the binding of methylmercury to hemoglobin and perhaps also selenium. As cord-blood mercury analyses appear to be less precise than suggested by laboratory quality data, we studied the interrelationships of mercury concentrations with hemoglobin in paired maternal and cord blood samples from a Faroese birth cohort (N=514) and the Mothers and Children's Environmental Health study in Korea (n=797). Linear regression and structural equation model (SEM) analyses were used to ascertain interrelationships between the exposure biomarkers and the possible impact of hemoglobin as well as selenium. Both methods showed a significant dependence of the cord-blood concentration on hemoglobin, also after adjustment for other exposure biomarkers. In the SEM, the cord blood measurement was a less imprecise indicator of the latent methylmercury exposure variable than other exposure biomarkers available, and the maternal hair concentration had the largest imprecision. Adjustment of mercury concentrations both in maternal and cord blood for hemoglobin improved their precision, while no significant effect of the selenium concentration in maternal blood was found. Adjustment of blood-mercury concentrations for hemoglobin is therefore recommended.
Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA; Department of Preventive Medicine, School of Medicine, Ewha Medical Research Center, Ewha Womans University, Seoul, South Korea.
Byung-Mi
BM
Kim
Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA.
Anna L
AL
Choi
Department of Preventive Medicine, School of Medicine, Ewha Medical Research Center, Ewha Womans University, Seoul, South Korea.
Eun-Hee
EH
Ha
Department of Clinical Chemistry & Pharmacology, Odense University Hospital, Odense, Denmark.
Lise
L
Pedersen
Institute of Public Health, University of Southern Denmark, Odense, Denmark.
Flemming
F
Nielsen
Faroese Hospital System, Torshavn, Faroe Islands.
Pal
P
Weihe
Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, South Korea.
Yun-Chul
YC
Hong
Department of Biostatistics, University of Copenhagen, Copenhagen, Denmark.
Esben
E
Budtz-Jørgensen
Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA; Institute of Public Health, University of Southern Denmark, Odense, Denmark. Electronic address: pgrand@hsph.harvard.edu.
Philippe
P
Grandjean
D000465:Algorithms; D015415:Biomarkers / Q000097:blood; D001774:Blood Chemical Analysis / Q000592:standards; D015331:Cohort Studies; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D016014:Linear Models; D018811:Maternal Exposure; D008628:Mercury / Q000097:blood*; D008767:Methylmercury Compounds / Q000097:blood; D011247:Pregnancy; D012643:Selenium / Q000097:blood
D015415:Biomarkers; D006454:Hemoglobins; D008767:Methylmercury Compounds; D008628:Mercury; D012643:Selenium
Blood analysis; Hemoglobin; Methylmercury; Prenatal exposure; Selenium