title: Total arsenic concentrations in toenails quantified by two techniques provide a useful biomarker of chronic arsenic exposure in drinking water.
abstract: Accurate quantitation of any contaminant of interest is critical for exposure assessment and metabolism studies that support risk assessment. A preliminary step in an arsenic exposure assessment study in Nevada quantified total arsenic (TAs) concentrations in tissues as biomarkers of exposure. Participants in this study (n=95) were at least 45 years old, had lived in the area for more than 20 years, and were exposed to a wide range of arsenic concentrations in drinking water (3-2,100 ppb). Concentrations of TAs in blood, urine, and toenails determined by hydride generation-atomic fluorescence spectrometry (HG-AFS) ranged from below detection to 0.03, 0.76, and 12 ppm, respectively; TAs in blood rarely exceeded the limit of detection. For comparison, TAs in toenails determined by neutron activation analysis (NAA) ranged from below detection to 16 ppm. Significant (P<0.0001) positive regressions were seen between the TAs concentration in toenails and in drinking water (adjusted r(2)=0.3557 HG-AFS, adjusted r(2)=0.3922 NAA); TAs concentrations in urine were not described by drinking water As (adjusted r(2)=0.0170, P=0.1369). Analyses of TAs in toenails by HGAFS and NAA yielded highly concordant estimates (r=0.7977, P<0.0001). These results suggest that toenails are a better biomarker of chronic As exposure than urine in the current study, because the sequestration of As in toenails provides an integration of exposure over time that does not occur in urine.
authors.affiliation: Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, United States Environmental Protection Agency, North Carolina 27711, USA. adair.blakely@epa.gov
authors.forename: Blakely M
authors.initials: BM
authors.lastname: Adair
authors.forename: Edward E
authors.initials: EE
authors.lastname: Hudgens
authors.forename: Michael T
authors.initials: MT
authors.lastname: Schmitt
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Calderon
authors.forename: David J
authors.initials: DJ
authors.lastname: Thomas
mesh_terms: D001151:Arsenic / Q000032:analysis* / Q000097:blood / Q000652:urine; D015415:Biomarkers / Q000032:analysis*; D006801:Humans; D013058:Mass Spectrometry; D009262:Nails / Q000737:chemistry*; D013054:Spectrophotometry, Atomic; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000097:blood / Q000652:urine
chemical_list: D015415:Biomarkers; D014874:Water Pollutants, Chemical; D001151:Arsenic