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Rice consumption contributes to arsenic exposure in US women

  1. Margaret R. Karagasa,b
  1. aChildren's Environmental Health and Disease Prevention Center at Dartmouth, Hanover, NH 03755;
  2. bSection of Biostatistics and Epidemiology, Department of Community and Family Medicine, Dartmouth Medical School, Hanover, NH 03756;
  3. cDepartment of Biological Sciences, Dartmouth College, Hanover, NH 03755;
  4. dDepartment of Pharmacology and Toxicology, University of Arizona, Tucson, AZ 85721;
  5. eDartmouth Hitchcock Medical Center, Lebanon, NH 03756; and
  6. fTrace Element Analysis Laboratory, Department of Earth Sciences, Dartmouth College, Hanover, NH 03755

  1. Edited by Jerome Nriagu, University of Michigan, Ann Arbor, MI, and accepted by the Editorial Board October 17, 2011 (received for review June 7, 2011)

Abstract

Emerging data indicate that rice consumption may lead to potentially harmful arsenic exposure. However, few human data are available, and virtually none exist for vulnerable periods such as pregnancy. Here we document a positive association between rice consumption and urinary arsenic excretion, a biomarker of recent arsenic exposure, in 229 pregnant women. At a 6-mo prenatal visit, we collected a urine sample and 3-d dietary record for water, fish/seafood, and rice. We also tested women's home tap water for arsenic, which we combined with tap water consumption to estimate arsenic exposure through water. Women who reported rice intake (n = 73) consumed a median of 28.3 g/d, which is ∼0.5 cup of cooked rice each day. In general linear models adjusted for age and urinary dilution, both rice consumption (g, dry mass/d) and arsenic exposure through water (μg/d) were significantly associated with natural log-transformed total urinary arsenic (Graphic, Graphic, both P < 0.0001), as well as inorganic arsenic, monomethylarsonic acid, and dimethylarsinic acid (each P < 0.005). Based on total arsenic, consumption of 0.56 cup/d of cooked rice was comparable to drinking 1 L/d of 10 μg As/L water, the current US maximum contaminant limit. US rice consumption varies, averaging ∼0.5 cup/d, with Asian Americans consuming an average of >2 cups/d. Rice arsenic content and speciation also vary, with some strains predominated by dimethylarsinic acid, particularly those grown in the United States. Our findings along with others indicate that rice consumption should be considered when designing arsenic reduction strategies in the United States.

Footnotes

  • ↵1D.G.-D. and K.L.C. contributed equally to this work.

  • ↵2To whom correspondence should be addressed. E-mail: diane.gilbert-diamond{at}dartmouth.edu.

  • Author contributions: K.L.C., T.P., C.L.F., and M.R.K. designed research; V.S., A.J.G., E.R.B., B.P.J., and M.R.K. performed research; D.G.-D., K.L.C., J.F.G., and M.R.K. analyzed data; and D.G.-D., K.L.C., J.F.G., T.P., and M.R.K. wrote the paper.

  • The authors declare no conflict of interest.

  • This article is a PNAS Direct Submission. J.N. is a guest editor invited by the Editorial Board.

  • This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1109127108/-/DCSupplemental.

Freely available online through the PNAS open access option.

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