Perchlorate Accumulation in Forage and Edible Vegetation

Abstract

The accumulation of perchlorate in vegetation is becoming a concern, with increasing numbers of sites reporting the presence of perchlorate in groundwater and surface water. This study investigated potential perchlorate uptake and distribution by a variety of forage and edible crops in both the laboratory and the field. Perchlorate concentrations in soybean leaves grown in the greenhouse were significantly higher than perchlorate concentrations in soybean seeds and pods. Perchlorate concentrations in alfalfa grown in sand were significantly lower than those in alfalfa grown in soil. The concentration of perchlorate in tomato was lower in the fruit than the leaves. Commercially grown wheat and alfalfa samples all contained perchlorate, 0.72-8.6 mg/kg of fresh weight (FW) in the wheat stems, 0.71-4.4 mg/kg of FW in the wheat heads, and 2.9 mg/kg of FW in alfalfa. All field garden samples tested (including cucumber, cantaloupe, and tomato) that were irrigated with perchlorate-tainted water contained perchlorate at various concentrations ranging from 0.040 to 1.65 mg/kg of FW. Bioconcentration factors (BCF), ratios of plant fresh weight concentrations to estimated or measured groundwater concentrations [(microg/kg of FW)/microg/L], were all in the same order of magnitude ranging from 215 +/- 126 for wheat stems to 233 +/- 264 for wheat heads and to 380 +/- 89 for alfalfa. BCF for garden fruit samples were much lower (0.5-20). Results from this study highlight the potential for perchlorate exposure by routes other than drinking water.

Drinking water contribution to aggregate perchlorate intake of reproductive-age women in the United States estimated by dietary intake simulation and analysis of urinary excretion data

“…Consistent with findings from previous studies or perchlorate concentrations in foods (Jackson et al, 2005;Sanchez et al, 2005a;Sanchez et al, 2005b;Murray et al, 2008;Sanchez et al, 2008), results from our dietary simulations suggest that drinking water contamination accounts for a relatively small proportion of total population intake for reproductive-age women in the United States. As shown in Table 5, addition of reasonable assumed drinking water perchlorate distributions increases the central tendency (mean and median) estimates of national perchlorate intakes for reproductive-age women by between approximately 3 and 24%.…”

Perchlorate exposure from food crops produced in the lower Colorado River region

“…In reality perchlorate has been found in agricultural products nationally and internationally outside the LCRR (FDA, 2004;Jackson et al, 2005;Sanchez et al, 2005a;El Aribi et al, 2006;Murray et al, 2008), including areas where there is no known contamination of water. Nevertheless, for instances in which we assume that individuals consume products from within and outside the LCRR, our estimates of exposure (Table 2) agree closely with those exploratory data reported by the FDA (FDA, 2007;Murray et al, 2008) for similar population groupings.…”

Perchlorate Exposure of the US Population, 2001–2002

“…For example, dietary habits such as the consumption of milk and green leafy vegetables vary across age and ethnicity groups. Samples of dairy milk and green-leafy vegetables have been reported to contain perchlorate (Hogue, 2003;Kirk et al, 2003;FDA, 2004;Capuco et al, 2005;Jackson et al, 2005). Therefore, increased consumption of these foods could increase perchlorate exposure (Blount et al, 2006).…”