title: In vivo assessment of arsenic bioavailability in rice and its significance for human health risk assessment.
abstract: BACKGROUND
  Millions of people worldwide consume arsenic-contaminated rice; however, little is known about the uptake and bioavailability of arsenic species after arsenic-contaminated rice ingestion.
  
  
  OBJECTIVE
  In this study, we assessed arsenic speciation in greenhouse-grown and supermarket-bought rice, and determined arsenic bioavailability in cooked rice using an in vivo swine model.
  
  
  RESULTS
  In supermarket-bought rice, arsenic was present entirely in the inorganic form compared to greenhouse-grown rice (using irrigation water contaminated with sodium arsenate), where most (approximately 86%) arsenic was present as dimethylarsinic acid (organic arsenic). Because of the low absolute bioavailability of dimethylarsinic acid and the high proportion of dimethylarsinic acid in greenhouse-grown rice, only 33 +/- 3% (mean +/- SD) of the total rice-bound arsenic was bioavailable. Conversely, in supermarket-bought rice cooked in water contaminated with sodium arsenate, arsenic was present entirely in the inorganic form, and bioavailability was high (89 +/- 9%).
  
  
  CONCLUSIONS
  These results indicate that arsenic bioavailability in rice is highly dependent on arsenic speciation, which in turn can vary depending on rice cultivar, arsenic in irrigation water, and the presence and nature of arsenic speciation in cooking water. Arsenic speciation and bioavailability are therefore critical parameters for reducing uncertainties when estimating exposure from the consumption of rice grown and cooked using arsenic-contaminated water.
authors.affiliation: Centre for Environmental Risk Assessment and Remediation, Division of Information Technology, Engineering and the Environment, University of South Australia, Adelaide, South Australia, Australia. Albert.Juhasz@unisa.edu.au
authors.forename: Albert L
authors.initials: AL
authors.lastname: Juhasz
authors.forename: Euan
authors.initials: E
authors.lastname: Smith
authors.forename: John
authors.initials: J
authors.lastname: Weber
authors.forename: Matthew
authors.initials: M
authors.lastname: Rees
authors.forename: Allan
authors.initials: A
authors.lastname: Rofe
authors.forename: Tim
authors.initials: T
authors.lastname: Kuchel
authors.forename: Lloyd
authors.initials: L
authors.lastname: Sansom
authors.forename: Ravi
authors.initials: R
authors.lastname: Naidu
mesh_terms: D000818:Animals; D001151:Arsenic / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D001682:Biological Availability; D002101:Cacodylic Acid / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D005506:Food Contamination / Q000032:analysis*; D006801:Humans; D012275:Oryza / Q000737:chemistry*; D018570:Risk Assessment; D013552:Swine
chemical_list: D002101:Cacodylic Acid; D001151:Arsenic