In vivo assessment of arsenic bioavailability in rice and its significance for human health risk assessment.
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.
Juhasz
Albert L
AL
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
Smith
Euan
E
Weber
John
J
Rees
Matthew
M
Rofe
Allan
A
Kuchel
Tim
T
Sansom
Lloyd
L
Naidu
Ravi
R
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
D002101:Cacodylic Acid; D001151:Arsenic