Perchlorate, nitrate, and iodine uptake and distribution in lettuce (Lactuca sativa L.) and potential impact on background levels in humans

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Abstract

Much focus has been placed on the impact of exposure to perchlorate (ClO4-) from drinking water. Recently, it has become more apparent that a significant percentage of the total ClO4- exposure may be due to ingestion of food. Most studies have only evaluated the uptake and distribution of ClO4- by plants without considering the potential for uptake of iodine (I) by the plant and the subsequent impacts on ClO4- uptake and distribution on human health. The objectives of this research effort were to evaluate the relative uptake of ClO4- and I supplied as either KI or KIO3, the two major environmental forms of I in a standard hydroponic nutrient solution using butter head lettuce. No interaction of ClO 4- uptake and distribution was found in the presence of I- or IO3- relative to previous studies evaluating ClO4- alone. Bioconcentration factors for ClO4- and total I in butter head lettuce when coexposed to both anions were similar for outer (292 ± 17 and 294 ± 12 L kg-1 of dry weight, respectively) and inner (76 ± 18 and 60 ± 8 L kg-1 of dry weight, respectively) leaves but not for roots (23 ± 3.7 and 359 ± 1.7 L kg-1 of dry weight, respectively) when the iodine was supplied as I-. The uptake of iodine was lower (BCF = 47 ± 3.8, 19 ± 0.6, and 189 ± 16, L kg-1 of dry weight for the outer and inner leaves and roots, respectively) for all tissues when iodine was supplied as IO3 -, with the greatest accumulation by the roots. These results suggest that if lettuce is grown using fertilizers containing both ClO4 - and I-, then the final ratio of IT/ClO 4 in the leaves will be essentially equal to the ratio in the fertilizer but lower if the I is supplied as IO3-. Therefore, the impact of the consumption of lettuce containing ClO 4- may be mitigated if the lettuce is grown using fertilizer with an appropriate amount of I to maintain the existing ratio of serum I to total goitrogen load (TGL). Nevertheless, the TGL in lettuce appeared to be almost completely dominated by NO3- with only a minor contribution of ClO4-, even for the highest exposure to ClO4-.

Original languageEnglish
Pages (from-to)12192-12198
Number of pages7
JournalJournal of Agricultural and Food Chemistry
Volume58
Issue number23
DOIs
StatePublished - Dec 8 2010

Keywords

  • Chilean nitrate fertilizer
  • Lactuca sativa
  • PEC
  • Perchlorate
  • TGL
  • iodate
  • iodide
  • iodine
  • lettuce

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