title: Biomonitoring equivalents for 2,2',4,4',5-pentabromodiphenylether (PBDE-99).
abstract: Biomonitoring Equivalents (BEs) are defined as the concentration or range of concentrations of a chemical or its metabolite in a biological medium (blood, urine, or other medium) that is consistent with an existing health-based exposure guideline such as a reference dose (RfD) or tolerable daily intake (TDI). BE values can be used as a screening tool for the evaluation of population-based biomonitoring data in the context of existing risk assessments. This study reviews health based risk assessments and exposure guidance values for 2,2',4,4',5-pentabromodiphenylether (PBDE-99) from Health Canada and the United States Environmental Protection Agency (US EPA). Toxicokinetic data from laboratory animals and humans are reviewed. A BE value corresponding to the US EPA RfD is derived here for PBDE-99 based on the assumption of chronic steady-state exposure, distribution into body lipids, and a previously-estimated first-order half-life of elimination of 1040days. The steady-state lipid-adjusted BE(RfD) is 520ng/g lipid. Sources of uncertainty relating to the underlying toxicokinetic and toxicologic database for PBDE-99 and the simultaneous exposure to multiple PBDE congeners are discussed. The BE(RfD) value may be used as a screening tool for evaluation of population biomonitoring data for PBDE-99 in the context of the existing US EPA risk assessment and can assist in prioritization of the potential need for additional risk assessment efforts for PBDE-99 relative to other chemicals.
authors.affiliation: Université de Montréal, Département de santé environnementale et santé au travail, Montréal, QC, Canada.
authors.forename: Kannan
authors.initials: K
authors.lastname: Krishnan
authors.forename: Therese
authors.initials: T
authors.lastname: Adamou
authors.forename: Lesa L
authors.initials: LL
authors.lastname: Aylward
authors.forename: Sean M
authors.initials: SM
authors.lastname: Hays
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Kirman
authors.forename: Andy
authors.initials: A
authors.lastname: Nong
mesh_terms: D000818:Animals; D002170:Canada; D004781:Environmental Exposure / Q000009:adverse effects; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000493:pharmacokinetics*; D017408:Guidelines as Topic; D006207:Half-Life; D055768:Halogenated Diphenyl Ethers / Q000493:pharmacokinetics*; D006801:Humans; D018570:Risk Assessment / Q000379:methods; D014018:Tissue Distribution; D014481:United States; D014484:United States Environmental Protection Agency
chemical_list: D004785:Environmental Pollutants; D055768:Halogenated Diphenyl Ethers; C086401:pentabromodiphenyl ether