Pendrin mediates uptake of perchlorate in a mammalian in vitro system

Efficiency of magnetic chitosan supported on graphene for removal of perchlorate ions from wastewater

In this study, we used a synthesized cross-linked magnetic chitosan with graphene oxide beads to study the removal of perchlorate from wastewater. The prepared complex was characterized using transmission electron microscopy (TEM), Fourier Transformation Infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM) and Thermal gravimetric analysis (TGA). Several parameters were studied including the effect of pH, contact time and the co-existing anions. The study showed that the adsorption could be studied in a wide range of pH. The study showed that the adsorption follows a pseudo-second-order model and Langmuir adsorption isotherm. The enthalpy and negative Gibbs standard free energy showed that the adsorption process was exothermic and spontaneous. The perchlorate adsorbent can be regenerated well by 0.1% NaCl solution.

Effects of perchlorate bioaccumulation on Spodoptera litura growth and sex ratio

Perchlorate (ClO4 (-)) pollution is widespread in the natural environment, but the effects of ClO4 (-) on the terrestrial insects are rarely studied. Here, when phytophagous insect Spodoptera litura larvae were fed on the diets with different ClO4 (-) concentrations, changes in their life-history traits were recorded; ClO4 (-) accumulations in feces and insect body were detected. The results demonstrated that ClO4 (-) bioaccumulation in insect at the different developmental stages was ranked in the order: adults > pupae > the 4th > 5th > 6th instar larvae. Besides, ClO4 (-) accumulations in the feces were ranked in the order: the 6th > 5th > 4th instar larvae. The ClO4 (-) accumulations in female pupae and adults were significantly higher than that in males. ClO4 (-) bioaccumulation in insect prolonged larval development time and caused a skewed sex ratio (the percentage of males at metamorphosis significantly decreased) under 100 to 200 mg ClO4 (-)/kg treatment. Therefore, ClO4 (-) accumulations in S. litura body presented developmental stage-, sex-specific pattern, and the sex-specific ClO4 (-) accumulations resulted in difference of sex ratio. These effects were observed at concentrations reported in natural environments contaminated with ClO4 (-), suggesting that this contaminant may pose a threat to the normal development and growth of this insect species.

Perchlorate-induced oxidative stress in isolated liver mitochondria

As a new threat to environment all through the world, perchlorate (ClO4(-)) was predominantly a thyrotoxin, and its toxic manifestations in non-thyroid were also documented. To date, little is known about the effect of ClO4(-) on cell and organelle. To reveal the toxicity of ClO4(-) on living organism in-depth, mitochondria isolated from liver of Carassius auratus were incubated with different concentrations of ClO4(-). The results demonstrated that ClO4(-)-induced mitochondrial oxidative stress, and subsequently caused a gradual opening of permeability transition pore leading to mitochondrial swelling and lipid peroxidative membrane damage. ClO4(-) has a conspicuous inhibition of electron transport chain activity which largely correlated to complexes I and IV. The investigations clearly demonstrated the oxidative stress of ClO4(-) in mitochondria, may well reveal cytotoxic effects in vitro that merit further investigation.

Spatial distribution of perchlorate, iodide and thiocyanate in the aquatic environment of Tianjin, China: environmental source analysis

Although China is the largest producer of fireworks (perchlorate-containing products) in the world, the pathways through which perchlorate enters the environment have not been characterized completely in this country. In this study, perchlorate, iodide and thiocyanate were measured in 101 water samples, including waste water, surface water, sea water and paired samples of rain water and surface runoff collected in Tianjin, China. The concentrations of the target anions were generally on the order of rain>surface water≈waste water treatment plant (WWTP) influent>WWTP effluent. High concentrations of perchlorate, iodide and thiocyanate were detected in rain samples, ranging from 0.35 to 27.3 (median: 4.05), 0.51 to 8.33 (2.92), and 1.31 to 107 (5.62) ngmL(-)(1), respectively. Furthermore, the concentrations of the target anions in rain samples were significantly (r=0.596-0.750, p<0.01) positively correlated with the concentrations obtained in the paired surface runoff samples. The anions tested showed a clear spatial distribution, and higher concentrations were observed in the upper reaches of rivers, sea waters near the coast, and rain-surface runoff pairs sampled in urban areas. Our results revealed that precipitation may act as an important source of perchlorate, iodide and thiocyanate in surface water. Moreover, iodide concentrations in the Haihe River and Dagu Drainage Canal showed a good correlation with an ideal marker (acesulfame) of domestic waste water, indicating that input from domestic waste water was an important source of iodide in the surface waters of Tianjin.

Removal of perchlorate from aqueous solution by cross-linked Fe(III)-chitosan complex

Cross-linked Fe(III)-chitosan composite (Fe-CB) was used as the adsorbent for removing perchlorate from the aqueous solution. The adsorption experiments were carried out by varying contact time, initial concentrations, temperatures, pH, and the presence of co-existing anions. The morphology of the adsorbent was discussed using FT-IR and SEM with X-EDS analysis. The pH ranging from 3.0-10.2 exhibited very little effect on the adsorption capability. The perchlorate uptake onto Fe-CB obeyed Langmuir isotherm model. The adsorption process was rapid and the kinetics data obeyed the pseudo second-order model well. The eluent of 2.5% (W/V) NaCl could regenerate the exhausted adsorbent efficiently. The adsorption mechanism was also discussed.

Seasonal variation and factors influencing perchlorate in water, snow, soil and corns in Northeastern China

Seasonal variation and influencing factors of perchlorate in snow, surface soil, rain, surface water, groundwater and corn were studied. Seven hundreds and seventy samples were collected in different periods in Harbin and its vicinity, China. Perchlorate concentrations were analyzed by ion chromatography-electrospray mass spectrometry. Results indicate that fireworks and firecrackers display from the Spring Festival to the Lantern Festival (February 2, 2011-February 17, 2011) can result in the occurrence of perchlorate in surface soil and snow. Perchlorate distribution is affected by wind direction in winter. Melting snow which contained perchlorate can dissolve perchlorate in surface soil, and then perchlorate can percolate into groundwater so that perchlorate concentrations in groundwater increased in spring. Perchlorate concentrations in groundwater and surface water decrease after rainy season in summer. Groundwater samples collected in the floodplain areas of the Songhua River and the Ashi River contained higher perchlorate concentrations than that far away with the rivers. The corns have the ability to accumulate perchlorate.

Perchlorate trophic transfer increases tissue concentrations above ambient water exposure alone in a predatory fish

This study examined effects of varying concentrations of the environmental contaminant perchlorate in northern pike (Esox lucius) based on exposure in water and/or from prey (threespine stickleback, Gasterosteus aculeatus). Routes of exposure to pike were through contaminated water at 0, 10, or 100 mg/L perchlorate for 49 d and/or through feeding, 1 per day over 14 d, sticklebacks that were previously maintained in water at 0, 10, or 100 mg/L perchlorate. Both water and food significantly contributed to pike tissue concentrations of perchlorate as compared to controls, but, as expected for a water-soluble contaminant, perchlorate did not biomagnify from prey to predatory fish. Pike gastrointestinal tissue retained significantly more perchlorate than other tissues combined. Route of exposure and concentration of perchlorate in various media are important to consider in risk assessment when evaluating uptake and tissue concentration of perchlorate because significantly higher tissue concentrations may result from combined prey and water exposures than from prey or water exposures alone in a concentration-dependent manner.

Radioactive iodide (131 I-) excretion profiles in response to potassium iodide (KI) and ammonium perchlorate (NH4ClO4) prophylaxis

Radioactive iodide (¹³¹I⁻) protection studies have focused primarily on the thyroid gland and disturbances in the hypothalamic-pituitary-thyroid axis. The objective of the current study was to establish ¹³¹I⁻ urinary excretion profiles for saline, and the thyroid protectants, potassium iodide (KI) and ammonium perchlorate over a 75 hour time-course. Rats were administered ¹³¹I⁻ and 3 hours later dosed with either saline, 30 mg/kg of NH₄ClO₄ or 30 mg/kg of KI. Urinalysis of the first 36 hours of the time-course revealed that NH₄ClO₄ treated animals excreted significantly more ¹³¹I⁻ compared with KI and saline treatments. A second study followed the same protocol, but thyroxine (T₄) was administered daily over a 3 day period. During the first 6–12 hour after ¹³¹I⁻ dosing, rats administered NH₄ClO₄ excreted significantly more ¹³¹I⁻ than the other treatment groups. T₄ treatment resulted in increased retention of radioiodide in the thyroid gland 75 hour after ¹³¹I⁻ administration. We speculate that the T₄ treatment related reduction in serum TSH caused a decrease synthesis and secretion of thyroid hormones resulting in greater residual radioiodide in the thyroid gland. Our findings suggest that ammonium perchlorate treatment accelerates the elimination rate of radioiodide within the first 24 to 36 hours and thus may be more effective at reducing harmful exposure to ¹³¹I⁻ compared to KI treatment for repeated dosing situations. Repeated dosing studies are needed to compare the effectiveness of these treatments to reduce the radioactive iodide burden of the thyroid gland.

Extrapolation of hypothalamic-pituitary-thyroid axis perturbations and associated toxicity in rodents to humans: case study with perchlorate

Functional aspects of the Hypothalamic-Pituitary-Thyroid (HPT) axis in rats and humans are compared, exposing why extrapolation of toxicant-induced perturbations in the rat HPT axis to the human HPT axis cannot be accomplished using default risk assessment methodology. Computational tools, such as biologically based dose response models for the HPT axis, are recommended to perform complex animal to human extrapolations involving the HPT axis. Experimental and computational evidence are presented that suggest perchlorate acts directly on the thyroid gland in rats. The apparent escape from perchlorate-induced inhibition of thyroidal uptake of radioactive iodide in humans is discussed along with "rebound" or increased thyroidal uptake of radioactive iodide observed after discontinued clinical treatment with perchlorate.