title: Development of biomonitoring equivalents for barium in urine and plasma for interpreting human biomonitoring data.
abstract: The objectives of the present work were: (1) to assemble population-level biomonitoring data to identify the concentrations of urinary and plasma barium across the general population; and (2) to derive biomonitoring equivalents (BEs) for barium in urine and plasma in order to facilitate the interpretation of barium concentrations in the biological matrices. In population level biomonitoring studies, barium has been measured in urine in the U.S. (NHANES study), but no such data on plasma barium levels were identified. The BE values for plasma and urine were derived from U.S. EPA's reference dose (RfD) of 0.2 mg/kg bw/d, based on a lower confidence limit on the benchmark dose (BMDL05) of 63 mg/kg bw/d. The plasma BE (9 μg Ba/L) was derived by regression analysis of the near-steady-state plasma concentrations associated with the administered doses in animals exposed to barium chloride dihydrate in drinking water for 2-years in a NTP study. Using a human urinary excretion fraction of 0.023, a BE for urinary barium (0.19 mg/L or 0.25 mg/g creatinine) was derived for US EPA's RfD. The median and the 95thpercentile barium urine concentrations of the general population in U.S. are below the BE determined in this study, indicating that the population exposure to inorganic barium is expected to be below the exposure guidance value of 0.2 mg/kg bw/d.
authors.affiliation: Health Canada, Ottawa, ON, Canada.
authors.forename: Devika
authors.initials: D
authors.lastname: Poddalgoda
authors.affiliation: Health Canada, Ottawa, ON, Canada.
authors.forename: Kristin
authors.initials: K
authors.lastname: Macey
authors.affiliation: Health Canada, Ottawa, ON, Canada.
authors.forename: Henry
authors.initials: H
authors.lastname: Assad
authors.affiliation: Risk Sciences International, Ottawa, ON, Canada. Electronic address: KKrishnan@Risksciences.com.
authors.forename: Kannan
authors.initials: K
authors.lastname: Krishnan
mesh_terms: D000818:Animals; D001464:Barium / Q000097:blood* / Q000652:urine*; D003404:Creatinine / Q000652:urine; D004781:Environmental Exposure; D004784:Environmental Monitoring; D006801:Humans; D009749:Nutrition Surveys; D012016:Reference Values; D018570:Risk Assessment
chemical_list: D001464:Barium; D003404:Creatinine
keywords: BE; Barium; Biomonitoring; Biomonitoring equivalent; Exposure guidance values