title: Chlorine isotopic composition of perchlorate in human urine as a means of distinguishing among exposure sources.
abstract: Perchlorate (ClO4(-)) is a ubiquitous environmental contaminant with high human exposure potential. Natural perchlorate forms in the atmosphere from where it deposits onto the surface of Earth, whereas synthetic perchlorate is manufactured as an oxidant for industrial, aerospace, and military applications. Perchlorate exposure can potentially cause adverse health effects in humans by interfering with the production of thyroid hormones through competitively blocking iodide uptake. To control and reduce perchlorate exposure, the contributions of different sources of perchlorate exposure need to be quantified. Thus, we demonstrate a novel approach for determining the contribution of different perchlorate exposure sources by quantifying stable and radioactive chlorine isotopes of perchlorate extracted from composite urine samples from two distinct populations: one in Atlanta, USA and one in Taltal, Chile (Atacama region). Urinary perchlorate from the Atlanta region resembles indigenous natural perchlorate from the western USA (δ(37)Cl=+4.1±1.0‰; (36)Cl/Cl=1 811 (±136) × 10(-15)), and urinary perchlorate from the Taltal, Chile region is similar to natural perchlorate in nitrate salt deposits from the Atacama Desert of northern Chile (δ(37)Cl=-11.0±1.0‰; (36)Cl/Cl=254 (±40) × 10(-15)). Neither urinary perchlorate resembled the isotopic pattern found in synthetic perchlorate. These results indicate that natural perchlorate of regional provenance is the dominant exposure source for the two sample populations, and that chlorine isotope ratios provide a robust tool for elucidating perchlorate exposure pathways.
authors: Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.
authors: Armen
authors: A
authors: Poghosyan
authors: Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
authors: Maria
authors: M
authors: Morel-Espinosa
authors: Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
authors: Liza
authors: L
authors: Valentin-Blasini
authors: Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
authors: Benjamin C
authors: BC
authors: Blount
authors: CENTRO FONDAP/ACCDIS, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors: Catterina
authors: C
authors: Ferreccio
authors: Arsenic Health Effects Research Program, School of Public Health, University of California, Berkeley, California, USA.
authors: Craig M
authors: CM
authors: Steinmaus
authors: Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.
authors: Neil C
authors: NC
authors: Sturchio
mesh_terms: D002713:Chlorine / Q000737:chemistry*; D004781:Environmental Exposure; D006801:Humans; D016273:Occupational Exposure; D010472:Perchlorates / Q000652:urine*
chemical_list: D010472:Perchlorates; D002713:Chlorine; C494474:perchlorate