title: Urinary and plasma fluoride levels in pregnant women from Mexico City.
abstract: There is need to assess the developmental neurotoxicity of fluoride. Our knowledge of prenatal fluoride exposure is challenged as few population-based studies have been conducted and these generally date back several decades, provide incomplete data on sociodemographic variables, and have methodological limitations.
  
  
  
  To measure urinary and plasma fluoride levels across three time points in pregnant mothers who were enrolled in the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) birth cohort study.
  
  
  
  Fluoride levels were characterized in archived urine and plasma from 872 pregnant mothers sampled from the ELEMENT cohort. Various statistical methods were used to analyze the fluoride data with particular consideration for changes across three stages of pregnancy and against sociodemographic variables.
  
  
  
  All samples had detectable levels of fluoride. The mean urinary and plasma fluoride levels were 0.91 and 0.0221mg/L respectively, and these were not statistically different across three stages of pregnancy. Fluoride levels correlated across the stages of pregnancy studied, with stronger correlations between neighboring stages. Urinary fluoride changed as pregnancy progressed with levels increasing until ~23 weeks and then decreasing until the end of pregnancy. For plasma fluoride, there was a decreasing trend but this was not of statistical significance. Creatinine-adjusted urinary fluoride levels did not associate consistently with any of the sociodemographic variables studied.
  
  
  
  This study provides the most extensive characterization to date of fluoride exposure throughout pregnancy. These results provide the foundation to explore exposure-related health outcomes in the ELEMENT cohort and other studies.
authors.affiliation: Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA.
authors.forename: Deena B
authors.initials: DB
authors.lastname: Thomas
authors.affiliation: Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA; Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada.
authors.forename: Niladri
authors.initials: N
authors.lastname: Basu
authors.affiliation: Department of Cariology, Operative Dentistry and Dental Public Health, Indiana University School of Dentistry, Indianapolis, Indiana, USA.
authors.forename: E Angeles
authors.initials: EA
authors.lastname: Martinez-Mier
authors.affiliation: Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, Michigan, USA.
authors.forename: Brisa N
authors.initials: BN
authors.lastname: Sánchez
authors.affiliation: Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, Michigan, USA.
authors.forename: Zhenzhen
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA.
authors.forename: Yun
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada.
authors.forename: Rajendra Prasad
authors.initials: RP
authors.lastname: Parajuli
authors.affiliation: Department of Human Nutrition, University of Michigan School of Public Health, Ann Arbor, Michigan, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Peterson
authors.affiliation: Center for Nutrition and Health Research, National Institute of Public Health, Cuernavaca, Morelos, México.
authors.forename: Adriana
authors.initials: A
authors.lastname: Mercado-Garcia
authors.affiliation: Occupational and Environmental Health, Dalla Lana School of Public Health, University of Toronto, Toronto, Canada.
authors.forename: Morteza
authors.initials: M
authors.lastname: Bashash
authors.affiliation: Center for Nutrition and Health Research, National Institute of Public Health, Cuernavaca, Morelos, México.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Hernández-Avila
authors.affiliation: Occupational and Environmental Health, Dalla Lana School of Public Health, University of Toronto, Toronto, Canada. Electronic address: Howard.Hu@utoronto.ca.
authors.forename: Howard
authors.initials: H
authors.lastname: Hu
authors.affiliation: Center for Nutrition and Health Research, National Institute of Public Health, Cuernavaca, Morelos, México.
authors.forename: Martha Maria
authors.initials: MM
authors.lastname: Téllez-Rojo
mesh_terms: D000328:Adult; D015331:Cohort Studies; D004784:Environmental Monitoring; D005260:Female; D005459:Fluorides / Q000097:blood* / Q000652:urine*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D018811:Maternal Exposure; D008431:Maternal-Fetal Exchange; D008800:Mexico; D011247:Pregnancy / Q000097:blood* / Q000652:urine*; D055815:Young Adult
chemical_list: D005459:Fluorides
keywords: Biomarkers; Exposure assessment; Fluoride; Pregnancy; Prenatal exposures; Public health