Perchlorate Accumulation and Potential Exposure from Durum Wheat Irrigated with Colorado River Water

Abstract

Abstract The Colorado River is contaminated with low levels of perchlorate derived from aerospace-and defense-related fuel industries once located near the Las Vegas Wash. At sufficiently high doses, perchlorate can disrupt thyroid function by inhibiting uptake of iodide. Researchers have reported on the presence of perchlorate in lettuce (Lactuca sativa L.) grown in the lower Colorado River region. Recent work has demonstrated the potential for wheat (Triticum aestivum L.) to accumulate perchlorate when irrigated with perchlorate contaminated irrigation water in Texas. Over 45 000 ha of durum wheat (Triticum turgidum var. durum) are irrigated with Colorado River water in Arizona and California for the national and international pasta industries. Studies were conducted to determine perchlorate accumulation of wheat irrigated with Colorado River water. Perchlorate did accumulate in the above-ground plant components (982 to 3924 µg/kg dry weight (dw)) and roots (96 to 650 µg/kg dw) of immature durum wheat. For mature wheat, concentrations were greater in the stalk (490 µg/kg dw) compared to the spike (80 µ/kg dw). Most of the detectable perchlorate in the spike was in the rachis (125 µ/kg dw) and glumes (236 µ/kg dw). A majority of grain samples collected had perchlorate concentrations below levels of quantification by ion chromatography with tandem mass spectrometry (IC/MS/MS) (25<25 µg/kg dw. These results indicate potential exposure from the consumption of pasta products derived from durum wheat irrigated with Colorado River water are low relative to the reference dose adopted by USEPA.