Perchlorate Accumulation Research Articles

Trends in the Exposure, Distribution, and Health Risk Assessment of Perchlorate among Crayfish in the Middle and Lower Reaches of the Yangtze River.

Perchlorate is a well-known thyroid-disrupting chemical as well as an extremely stable inorganic pollutant widely distributed in the environment. Therefore, perchlorate posts potential risks to the environment as well as human health. Crayfish is a dominant aquatic food with increasing consumption levels in recent years. It is crucial to evaluate the accumulation of perchlorate with well-water-soluble properties in crayfish and to assess its health risks. In our present study, we obtained crayfish samples from cultivated ponds and markets based on the regions of the Middle and Lower Reaches of the Yangtze River. The perchlorate concentration was measured in all 206 samples using ultra-high performance liquid chromatography coupled with mass spectrometry (UPLC–MS). Monte Carlo simulation was used to perform health risk assessments. The results indicated that perchlorate levels ranged from 7.74–43.71 μg/kg for cultivated crayfish and 4.90–16.73 μg/kg for crayfish sold in markets. The perchlorate accumulation mainly occurred in exoskeleton parts. All the HQ values were remarkable, at less than one—indicating that perchlorate exposure through the ingestion of crayfish does not pose an appreciable risk to human health.

Novel insight into the resilient drivers of bioaccumulation perchlorate on lipid nutrients alterations in goat milk by spatial multi-omics

The migration of perchlorate into dairy products through water or detergent is becoming increasingly serious. Spatiotemporal profiles of lipid nutrients associated with perchlorate response were investigated by spatial multi-omics of goat milk. In response to perchlorate accumulation, lipoprotein lipase activity was inhibited in glycerolipid metabolism, thereby resulting in the excessive accretion of triglycerides. Goat milk was selected as the test matrix and conducted to simulate the biological cumulation of perchlorate and evaluate effects of different dietary perchlorate levels (0.0–2.0 mg/kg) on nutritional quality of goat milk. Perchlorate altered phospholipase A2 expression level, affected glycerophospholipid metabolism thus triggered significant changes in phosphatidylcholine (23.35–31.88 μg/mL). Excess triacylglycerol accumulation (3259–6032 μg/mL) caused by perchlorate was due to the inhibition of glycerolipid metabolism mediated by lipoprotein lipase. The study indicated that dietary perchlorate exposure resulted in the decline of nutritional quality in goat milk, which indirectly posed a serious threat to the health of consumers.

Differential Responses of Two Rice Varieties to Perchlorate Stress

Two rice varieties, one perchlorate-tolerant (Gannuoxiang, GN) and the other perchlorate-sensitive (IR65598-112-2, IR), were exposed to 20, 200, and 400 mg/kg soil perchlorate to investigate their physiological responses and perchlorate accumulation. It was found that perchlorate decreased leaf chlorophyll content in both rice varieties. The activities of superoxide dismutase (SOD) and catalase (CAT) decreased while peroxidase (POD) increased in both rice varieties under perchlorate stress at tillering stage. Rice variety IR showed earlier physiological response and was more affected by perchlorate than GN. Perchlorate induced physiological response in different ways depending on perchlorate contamination level, rice variety, and growing stage. Perchlorate concentration in leaves was significantly higher than that in roots, stems and seeds. Perchlorate accumulation in IR leaves was higher than GN, but GN stored more perchlorate in its edible portion at low perchlorate level. These results indicated that high sensitivity of the rice variety IR to perchlorate stress might be due to antioxidant enzymes in perchlorate-detoxification and its higher perchlorate accumulation in leaves.

Effects of perchlorate on growth of four wetland plants and its accumulation in plant tissues

Perchlorate contamination in water is of concern because of uncertainties about toxicity and health effects, impact on ecosystems, and possible indirect exposure pathways to humans. Therefore, it is very important to investigate the ecotoxicology of perchlorate and to screen plant species for phytoremediation. Effects of perchlorate (20, 200, and 500 mg/L) on the growth of four wetland plants (Eichhornia crassipes, Acorus calamus L., Thalia dealbata, and Canna indica) as well as its accumulation in different plant tissues were investigated through water culture experiments. Twenty milligrams per liter of perchlorate had no significant effects on height, root length, aboveground part weight, root weight, and oxidizing power of roots of four plants, except A. calamus, and increasing concentrations of perchlorate showed that out of the four wetland plants, only A. calamus had a significant (p<0.05) dose-dependent decrease in these parameters. When treated with 500 mg/L perchlorate, these parameters and chlorophyll content in the leaf of plants showed significant decline contrasted to control groups, except the root length of E. crassipes and C. indica. The order of inhibition rates of perchlorate on root length, aboveground part weight and root weight, and oxidizing power of roots was: A. calamus > C. indica > T. dealbata > E. crassipes and on chlorophyll content in the leaf it was: A. calamus > T. dealbata > C. indica > E. crassipes. The higher the concentration of perchlorate used, the higher the amount of perchlorate accumulation in plants. Perchlorate accumulation in aboveground tissues was much higher than that in underground tissues and leaf was the main tissue for perchlorate accumulation. The order of perchlorate accumulation content and the bioconcentration factor in leaf of four plants was: E. crassipes > C. indica > T. dealbata > A. calamus. Therefore, E. crassipes might be an ideal plant with high tolerance ability and accumulation ability for constructing wetland to remediate high levels of perchlorate polluted water.

Perchlorate transport and inhibition of the sodium iodide symporter measured with the yellow fluorescent protein variant YFP-H148Q/I152L

Perchlorate is an environmental contaminant that impairs thyroid function by interacting with the sodium iodide symporter (NIS), the transporter responsible for iodide uptake in the thyroid gland. Perchlorate is well known as a competitive inhibitor of iodide transport by NIS, and recent evidence demonstrates that NIS can also transport perchlorate. In this study, we evaluated the yellow fluorescent protein (YFP) variant YFP-H148Q/I152L, as a genetically encodable biosensor of intracellular perchlorate concentration monitored by real-time fluorescence microscopy. Fluorescence of recombinant YFP-H148Q/I152L was suppressed by perchlorate and iodide with similar affinities of 1.2 mM and 1.6 mM, respectively. Perchlorate suppressed YFP-H148Q/I152L fluorescence in FRTL-5 thyroid cells and NIS-expressing COS-7 cells, but had no effect on COS-7 cells lacking NIS. Fluorescence changes in FRTL-5 cells were Na +-dependent, consistent with the Na +-dependence of NIS activity. Perchlorate uptake in FRTL-5 cells resulted in 10-fold lower intracellular concentrations than iodide uptake, and was characterized by a higher affinity ( K m 4.6 μM for perchlorate and 34.8 μM for iodide) and lower maximal velocity ( V max 6.8 μM/s for perchlorate and 39.5 μM/s for iodide). Perchlorate also prevented iodide-induced changes in YFP-H148Q/I152L fluorescence in FRTL-5 cells, with half-maximal inhibition occurring at 1.1–1.6 μM. In conclusion, YFP-H148Q/I152L detects perchlorate accumulation by thyroid and other NIS-expressing cells, and reveals differences in the kinetics of perchlorate versus iodide transport by NIS.

Perchlorate accumulation and migration in the deep vadose zone in a semiarid region

Summary For 25 years, a plant in Israel manufacturing ammonium perchlorate disposed of untreated wastewater in four unlined ponds. This study explores the transport mechanisms of perchlorate infiltrated from 1965 to 1990 from one of these active storage ponds into a deep (40 m) layered vadose zone and the underlying Israeli coastal aquifer. Perchlorate migration from 1990, when wastewater disposal ceased, until today, with infiltration due only to natural rain (∼500 mm y −1 ), was also studied. Several indirect methods were used, including: mass balance in the unsaturated zone profile, δ 18 O and δ 2 H profiles below the pond, and a comparison of the same sediment profiles in 2005 and 2007. The isotopic composition of the pore water could be divided into two separate groups: lighter (depleted) and heavier (enriched) samples. All samples in the lighter group were from the shallow vadose zone, above two clayey layers, and represent natural infiltration of rainwater. The enriched samples were from the deeper section of the unsaturated zone (20–40 m) and represent water used for perchlorate manufacturing 14 years prior to drilling. Consequently, the overall maximum infiltration rate was estimated to be 1.4 m y −1 . Below the clayey layer almost identical perchlorate concentrations were found along the sediment profile in 2005 and 2007 (two boreholes, 3 m apart). Very different perchlorate profiles were observed above the clayey layers. This suggests that perchlorate below the clay layers (20–40 m) is practically stagnant under the current natural conditions. The reduction in perchlorate concentration in groundwater below the ponds vs. its increased concentration further downgradient supports the contention that the current migration of perchlorate from the vadose zone to the groundwater is very small. We estimate that perchlorate concentration in the groundwater under the infiltration pond, which was 187 mg l −1 in 2004, will reach 10 μg l −1 within about 14 years. The existence of a clayey layer crossing the thick vadose zone was thus found to significantly change the infiltration rate when ponded conditions were replaced with natural precipitation.

Perinatal exposure to perchlorate. thiocyanate, and nitrate in New Jersey mothers and newborns.

Perchlorate is a commonly occurring environmental toxicant that may be transported across the placental barrier by the sodium-iodide symporter (NIS), possibly resulting in both increased perchlorate exposure and decreased iodide uptake by the fetus. Therefore, we measured levels of three physiologically relevant NIS-inhibitors (perchlorate, nitrate, and thiocyanate) and iodide in maternal and fetal fluids collected during cesarean-section surgeries on 150 U.S. women. Geometric means of perchlorate, thiocyanate, and nitrate levels in maternal urine (2.90, 947, and 47900 microg/L, respectively) were similar to previously published results, while urinary iodide levels (1420 microg/L) were significantly higher (p < 0.0001), likely because of prevalent prenatal vitamin use in the study population (74%). Thiocyanate levels were higher in the maternal serum, cord serum, and amniotic fluid of smokers compared to women with environmental tobacco smoke exposure and nonsmokers (p-values of 0.0006, 0.0011, and 0.0026, respectively). Perchlorate was detected in most samples: urine (100%), maternal serum (94%), cord serum (67%), and amniotic fluid (97%). Maternal urinary perchlorate levels were positively correlated with perchlorate levels in amniotic fluid (r = 0.57), indicating that maternal urine perchlorate is an effective biomarker of fetal perchlorate exposure. Maternal serum perchlorate was generally higher than cord serum perchlorate (median ratio 2.4:1 for paired samples), and maternal urine perchlorate was always higher than fetal amniotic fluid perchlorate levels (mean ratio 22:1); conversely, iodide levels were typically higher in fetal fluids compared to maternal fluids. We found no evidence of either disproportionate perchlorate accumulation or lack of iodide in the fetal compartment. In this panel of healthy infants, we found no association between cord blood levels of these anions and newborn weight length, and head circumference.

Perchlorate, Nitrate, Thiocyanate, and Iodide Levels in Chicken Feed, Water, and Eggs from Three Farms

Perchlorate is an inhibitor of iodide uptake that is found widely in the environment. Given the potential for perchlorate accumulation during egg formation and the widespread consumption of eggs, it is important to examine eggs as a source of exposure to perchlorate and other potential inhibitors of iodide uptake (nitrate and thiocyanate). This study was conducted to determine potential human exposure to perchlorate from eggs produced by chicken flocks consuming differing amounts of perchlorate. The mean concentrations of perchlorate (7.16 ( 1.99 microg/kg of dry weight), nitrate (2820 ( 2100 microg/kg of dry weight), thiocyanate (574 +/- 433 microg/kg of dry weight), and iodide (2980 ( 1490 microg/kg of dry weight) in eggs (n = 180) from 15 chicken houses on 3 U.S. farms were determined. Chickens secreted into eggs an average of 23% of the perchlorate ingested from feed and water. Perchlorate levels in eggs were positively correlated with perchlorate intake (p < 0.001). Increased intake of perchlorate, nitrate, and thiocyanate was associated with decreased iodide levels in eggs, possibly indicating a competitive transport mechanism, such as sodium-iodide symporter. It was estimated that egg consumption contributes minimal perchlorate (approximately 0.040 microg) compared to the average total intake of approximately 10.5 microg for U.S. adults. Additionally, it was found that egg consumption was not associated with increased perchlorate exposure in 2820 individuals from the National Health and Nutrition Examination Survey (p value for the difference of least-squares means, pDiff = 0.225). From these findings it was concluded that, although chickens secrete perchlorate in eggs, eggs do not appear to be a significant source of perchlorate exposure for adults in the United States.

Thyroid-stimulating hormone increases active transport of perchlorate into thyroid cells

Perchlorate blocks thyroidal iodide transport in a dose-dependent manner. The human sodium/iodide symporter (NIS) has a 30-fold higher affinity for perchlorate than for iodide. However, active transport of perchlorate into thyroid cells has not previously been demonstrated by direct measurement techniques. To demonstrate intracellular perchlorate accumulation, we incubated NIS-expressing FRTL-5 rat thyroid cells in various concentrations of perchlorate, and we used a sensitive ion chromatography tandem mass spectrometry method to measure perchlorate accumulation in the cells. Perchlorate caused a dose-related inhibition of 125-iodide uptake at 1-10 microM. The perchlorate content from cell lysate was analyzed, showing a higher amount of perchlorate in cells that were incubated in medium with higher perchlorate concentration. Thyroid-stimulating hormone increased perchlorate uptake in a dose-related manner, thus supporting the hypothesis that perchlorate is actively transported into thyroid cells. Incubation with nonradiolabeled iodide led to a dose-related reduction of intracellular accumulation of perchlorate. To determine potential toxicity of perchlorate, the cells were incubated in 1 nM to 100 microM perchlorate and cell proliferation was measured. Even the highest concentration of perchlorate (100 microM) did not inhibit cell proliferation after 72 h of incubation. In conclusion, perchlorate is actively transported into thyroid cells and does not inhibit cell proliferation.

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

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&amp;lt;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.

Accumulation and perchlorate exposure potential of lettuce produced in the Lower Colorado River region.

The Colorado River is contaminated with perchlorate concentrations of 1.5-8 microg/L, an anion linked to thyroid dysfunction. Over 90% of the lettuce (Lactuca sativa L.) consumed during the winter months in the United States is produced in the Lower Colorado River region. Studies were conducted in this region to survey the potential for lettuce perchlorate accumulation and estimate potential human exposure to perchlorate from lettuce. Total uptake of perchlorate in the above-ground plant of iceberg lettuce was approximately 5 g/ha. Exposure estimates ranged from 0.45 to 1.8 microg/day depending on lettuce types and trimming. For all lettuce types, hypothetical exposures were less than 4% of the reference dose recommended by the National Academy of Sciences. Results show the relative iodide uptake inhibition potential because of lettuce nitrate was 2 orders of magnitude greater than that associated with the corresponding trace levels of perchlorate. These data support the conclusion that potential perchlorate exposures from lettuce irrigated with Colorado River water are negligible relative to acute or long-term harmful amounts.

Perchlorate Accumulation in Forage and Edible Vegetation

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.

Accumulation of perchlorate in aquatic and terrestrial plants at a field scale.

Previous laboratory-scale studies have documented perchlorate ClO(-)(4) uptake by different plant species, but less information is available at field scale, where ClO(-)(4) uptake may be affected by environmental conditions, such as distance to streams or shallow water tables, exposure duration, and species. This study examined uptake of ClO(-)(4) in smartweed (Polygonum spp.) and watercress (Nasturtium spp.) as well as more than forty trees, including ash (Fraxinus greggii A. Gray), chinaberry (Melia azedarach L.), elm (Ulmus parvifolia Jacq.), willow (Salix nigra Marshall), mulberry [Broussonetia papyrifera (L.) Vent.], and hackberry (Celtis laevigata Willd.) from multiple streams surrounding a perchlorate-contaminated site. Results indicate a large potential for ClO(-)(4) accumulation in aquatic and terrestrial plants, with ClO(-)(4) concentration in plant tissues approximately 100 times higher than that in bulk water. Perchlorate accumulation in leaves of terrestrial plants was also dependent on species, with hackberry, willow, and elm having a strong potential to accumulate ClO(-)(4). Generally, trees located closer to the stream had a higher ClO(-)(4) accumulation than trees located farther away from the stream. Seasonal leaf sampling of terrestrial plants indicated that ClO(-)(4) accumulation also was affected by exposure duration, with highest accumulation observed in the late growing cycle, although leaf concentrations for a given tree were highly variable. Perchlorate may be re-released into the environment via leaching and rainfall as indicated by lower perchlorate concentrations in collected leaf litter. Information obtained from this study will be helpful to understand the fate of ClO(-)(4) in macrophytes and natural systems.

Perchlorate Identification in Fertilizers

Perchlorate has contaminated groundwater, drinking water, and soils at several locations in the United States. The primary source of contamination at sites that have been investigated to date seems to be from industrial and military operations that use perchlorate as an oxidizing agent. However, recent examination of several fertilizers and fertilizer components showed that perchlorate is present at levels up to 0.84 wt %. These preliminary results suggest that fertilizers could be a source for perchlorate accumulation in the food chain.

Determination of perchlorate accumulation in flame atomic absorption systems by ion-pairing chromatography

Perchlorate accumulation in flame atomic absorption systems has been studied using ion-pairing chromatography with indirect photometric detection. The results indicate that highly variable amounts of chloride are produced during the aspiration of perchlorate salts. Perchlorate accumulation was found to be related to the species aspirated and to the burner and spray chamber design. The effects of flame stoicheiometry, rinsing and preventative additives are discussed. The chromatographic technique and experimental design may assist in improving atomic absorption systems in order to provide optimised safety with respect to perchlorate-induced spray-chamber explosions.