title: Exposure assessment issues in epidemiology studies of phthalates.
abstract: OBJECTIVE
  The purpose of this paper is to review exposure assessment issues that need to be addressed in designing and interpreting epidemiology studies of phthalates, a class of chemicals commonly used in consumer and personal care products. Specific issues include population trends in exposure, temporal reliability of a urinary metabolite measurement, and how well a single urine sample may represent longer-term exposure. The focus of this review is on seven specific phthalates: diethyl phthalate (DEP); di-n-butyl phthalate (DBP); diisobutyl phthalate (DiBP); butyl benzyl phthalate (BBzP); di(2-ethylhexyl) phthalate (DEHP); diisononyl phthalate (DiNP); and diisodecyl phthalate (DiDP).
  
  
  METHODS
  Comprehensive literature search using multiple search strategies.
  
  
  RESULTS
  Since 2001, declines in population exposure to DEP, BBzP, DBP, and DEHP have been reported in the United States and Germany, but DEHP exposure has increased in China. Although the half-lives of various phthalate metabolites are relatively short (3 to 18h), the intraclass correlation coefficients (ICCs) for phthalate metabolites, based on spot and first morning urine samples collected over a week to several months, range from weak to moderate, with a tendency toward higher ICCs (greater temporal stability) for metabolites of the shorter-chained (DEP, DBP, DiBP and BBzP, ICCs generally 0.3 to 0.6) compared with those of the longer-chained (DEHP, DiNP, DiDP, ICCs generally 0.1 to 0.3) phthalates. Additional research on optimal approaches to addressing the issue of urine dilution in studies of associations between biomarkers and different type of health effects is needed.
  
  
  CONCLUSIONS
  In conclusion, the measurement of urinary metabolite concentrations in urine could serve as a valuable approach to estimating exposure to phthalates in environmental epidemiology studies. Careful consideration of the strengths and limitations of this approach when interpreting study results is required.
authors: Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48103, USA. Electronic address: laujohns@umich.edu.
authors: Lauren E
authors: LE
authors: Johns
authors: National Center for Environmental Assessment, Office of Research and Development, United States Environmental Protection Agency, 1200 Pennsylvania Avenue NW, Washington DC 20460, USA. Electronic address: Cooper.Glinda@epa.gov.
authors: Glinda S
authors: GS
authors: Cooper
authors: National Center for Environmental Assessment, Office of Research and Development, United States Environmental Protection Agency, 2890 Woodbridge Avenue, Edison, NJ 08837, USA. Electronic address: Galizia.Audrey@epa.gov.
authors: Audrey
authors: A
authors: Galizia
authors: Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48103, USA. Electronic address: meekerj@umich.edu.
authors: John D
authors: JD
authors: Meeker
mesh_terms: D015415:Biomarkers / Q000652:urine; D002681:China; D003993:Dibutyl Phthalate / Q000031:analogs & derivatives / Q000652:urine; D004781:Environmental Exposure / Q000032:analysis* / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000652:urine*; D005260:Female; D006801:Humans; D010795:Phthalic Acids / Q000652:urine*; D015203:Reproducibility of Results
chemical_list: D015415:Biomarkers; D004785:Environmental Pollutants; D010795:Phthalic Acids; D003993:Dibutyl Phthalate; C012125:diisononyl phthalate; C032279:phthalic acid; C025605:diisobutyl phthalate; C007379:diethyl phthalate; C042080:diisodecyl phthalate; C027561:butylbenzyl phthalate
keywords: Biomarkers; Biomonitoring; Environmental epidemiology; Exposure assessment; Metabolites; Phthalates; Temporal reliability; Trends