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PubMed2006

Perchlorate induces hermaphroditism in threespine sticklebacks.

Recently, concern regarding perchlorate contamination has arisen in many contexts. Perchlorate has many military, commercial, and domestic applications, and it has been found in milk, drinking and irrigation water, and produce. Perchlorate is harmful at low levels, yet it remains unregulated in the United States while the U.S. Environmental Protection Agency attempts to establish acceptable exposure levels. The present study investigated potential reproductive effects on vertebrates using a model fish species, the threespine stickleback (Gasterosteus aculeatus). Sticklebacks were raised from syngamy through sexual maturity in untreated water and in three target concentrations of sodium perchlorate-treated water. Perchlorate was found to interfere with the expression of nuptial coloration, courtship behavior, and normal sexual development. Genetic testing revealed that some females were masculinized to the extent that they produced both sperm and eggs, and histological analysis showed that these individuals had intersexual gonads (ovotestes) containing both oocytes and cells undergoing spermatogenesis. In vitro fertilizations revealed that those gametes were capable of self- and cross-fertilization. However, crosses using sperm derived from genetic females died either during the blastula phase or near the onset of organogenesis. Sperm derived from genetic males produced viable fry when crossed with eggs derived from genetic females from all treatments. To our knowledge, the present study provides the first evidence that perchlorate produces androgenic effects and is capable of inducing functional hermaphroditism in a nonhermaphroditic vertebrate.

Animals↗
PubMed1977

Stability of aqueous perchlorate formulations.

The stability of three aqueous perchlorate formulations used in nuclear medicine was studied as a function of the formulation and storage temperature. The formulations were intravenous potassium perchlorate solution, oral sodium perchlorate-sorbitol solution and oral potassium perchlorate in cherry syrup solution. The assays were conducted gravimetrically by precipitation with tetra-n-pentylammonium bromide. All formulations were found to be stable at least nine months. It is recommended that any formulation containing potassium perchlorate be kept at room temperature since precipitation of the active ingredient may occur if refrigerated. Sodium perchlorate formulations, however, may be refrigerated if desired because of their greater solubility.

Drug Stability↗
PubMed2005

Gas-phase ion association provides increased selectivity and sensitivity for measuring perchlorate by mass spectrometry.

Perchlorate (ClO4-) competitively inhibits the uptake of iodide by the thyroid gland. Trace quantities of perchlorate are being increasingly detected in food and environmental samples. There is great concern that perchlorate contamination may be far more widespread than believed until now. Increasingly sensitive and unambiguous methods are needed for measuring perchlorate. We report here an ion chromatography-ion association-electrospray ionization-mass spectrometry (IC/IA-ESI-MS) method of substantially greater selectivity and sensitivity than other available single-stage MS approaches. A long chain dipositive cationic agent (D2+) is added postcolumn in low concentration. This ion associates with perchlorate, even in the gas phase. Perchlorate is, thus, detected as DClO4+ in the positive ion mode at an m/z value between 300 and 400 (depending on the choice of D2+). This results in much better S/N and selectivity, as compared to detecting 35ClO4- at m/z 99, where H34SO4- also responds. We show results for various dicationic agents which vary in their selectivity and affinity for ClO4-, typically being at least 1 order of magnitude more selective for ClO4- over HSO4-. For a 100-microL injected standard, limits of detection (LOD, S/N = 3) are as good as 25 ng/L on a single quadrupole mass spectrometer. Calibration for concentrations up to 100 microg/L displays an r2 value of > or =0.9993. We show applicability to various real samples. A number of the studied reagents are suitable for such applications.

Journal Article↗
PubMed2005

Dracorhodin perchlorate induces A375-S2 cell apoptosis via accumulation of p53 and activation of caspases.

Dracorhodin perchlorate, an anthocyanin red pigment, induces human melanoma A375-S2 cell death through the apoptotic pathway. Caspase-3, -8, -9, and -10 inhibitors partially reversed the cell death induced by dracorhodin perchlorate. Caspase-3 and -8 were activated, followed by the degradation of caspase-3 substrates, the inhibitor of caspase-activated DNase, and poly-(ADP-ribose) polymerase. Dracorhodin perchlorate upregulated the expression ratio of Bax/Bcl-2 and significantly increased the expression of p53 and p21(WAF1) proteins. The cell death was partially reduced by the mitogen-activated protein kinase c-JUN NH2-terminal protein kinase (JNK MAPK) inhibitor (SP600125) and p38 MAPK inhibitor (SB 203580), while the MEK inhibitor (PD98059) augmented cell death; the drug induced sustained phosphorylation of JNK and p38 MAPK. Moreover, the Fas agonistic antibody CH-11 has a synergistic effect with dracorhodin perchlorate. The phoshatidylinositol 3-kinase (PI3-K) family inhibitor wortmanin and tyrosine kinase inhibitor genistein rescued the viability loss induced by dracohodin perchlorate. Taken together, dracorhodin perchlorate induces apoptosis in A375-S2 cells via accumulation of p53, alters the Bax/Bcl-2 ratio, and activates caspases and p38/JNK MAPKs.

Apoptosis↗
PubMed2000

Neonatal thyroid-stimulating hormone level and perchlorate in drinking water.

BACKGROUND: The effect of perchlorate in drinking water on neonatal blood thyroid-stimulating hormone (thyrotropin; TSH) levels was examined for Las Vegas and Reno, Nevada. METHODS: The neonatal blood TSH levels in Las Vegas (with up to 15 microg/L (ppb) perchlorate in drinking water) and in Reno (with no perchlorate detected in the drinking water) from December 1998 to October 1999 were analyzed and compared. The study samples were from newborns in their first month of life (excluding the first day of life) with birth weights of 2, 500-4,500 g. A multivariate analysis of logarithmically transformed TSH levels was used to compare the mean TSH levels between Las Vegas and Reno newborns, with age and sex being controlled as potential confounders. RESULTS: This study of neonatal TSH levels in the first month of life found no effect from living in the areas with environmental perchlorate exposures of </=15 microg/L (P = 0.97). CONCLUSIONS: This study, which was sensitive enough to detect the effects of age and gender on neonatal blood TSH levels, detected no effect from environmental exposures to perchlorate.

Age Factors↗
PubMed2004

Isolation and characterization of autotrophic, hydrogen-utilizing, perchlorate-reducing bacteria.

Recent studies have shown that perchlorate (ClO(4) (-)) can be degraded by some pure-culture and mixed-culture bacteria with the addition of hydrogen. This paper describes the isolation of two hydrogen-utilizing perchlorate-degrading bacteria capable of using inorganic carbon for growth. These autotrophic bacteria are within the genus Dechloromonas and are the first Dechloromonas species that are microaerophilic and incapable of growth at atmospheric oxygen concentrations. Dechloromonas sp. JDS5 and Dechloromonas sp. JDS6 are the first perchlorate-degrading autotrophs isolated from a perchlorate-contaminated site. Measured hydrogen thresholds were higher than for other environmentally significant, hydrogen-utilizing, anaerobic bacteria (e.g., halorespirers). The chlorite dismutase activity of these bacteria was greater for autotrophically grown cells than for cells grown heterotrophically on lactate. These bacteria used fumarate as an alternate electron acceptor, which is the first report of growth on an organic electron acceptor by perchlorate-reducing bacteria.

Bacteria↗
PubMed1987

The perchlorate discharge test for examining thyroid function in rats.

A perchlorate discharge test was developed for rats to detect changes in the thyroidal iodide accumulation and organification mechanisms. Rats were pretreated with compounds that alter thyroid function by different mechanisms: SK&F 93479 (an H2-antagonist that enhances pituitary thyroid stimulating hormone drive by increasing thyroid hormone clearance) and propylthiouracil (an inhibitor of iodide organification). Six hours following administration of 125I, either potassium perchlorate (10 mg/kg x 2.5 min) or saline was given i.p. Perchlorate significantly reduced the thyroid: blood 125I ratio in propylthiouracil-treated rats but had no effect in those pretreated with SK&F 93479, indicating an iodide organification block in the former. At the same time thyroidal radioiodide accumulation in SK&F 93479-treated rats (no perchlorate) was enhanced, whereas that in propylthiouracil-treated animals (no perchlorate) was depressed.

Animals↗
PubMed2005

Equilibrium unfolding of dimeric and engineered monomeric forms of lambda Cro (F58W) repressor and the effect of added salts: evidence for the formation of folded monomer induced by sodium perchlorate.

The equilibrium unfolding transitions of Cro repressor variants, dimeric variant Cro F58W and monomer Cro K56[DGEVK]F58W, have been studied by urea and guanidine hydrochloride to probe the folding mechanism. The unfolding transitions of a dimeric variant are well described by a two state process involving native dimer and unfolded monomer with a free energy of unfolding, DeltaG(0,un)(0), of approximately 10-11 kcal/mol. The midpoint of transition curves is dependent on total protein concentration and DeltaG(0,un)(0) is independent of protein concentration, as expected for this model. Unfolding of Cro monomer is well described by the standard two state model. The stability of both forms of protein increases in the presence of salt but decreases with the decrease in pH. Because of the suggested importance of a N2<-->2F dimerization process in DNA binding, we have also studied the effect of sodium perchlorate, containing the chaotropic perchlorate anion, on the conformational transition of Cro dimer by CD, fluorescence and NMR (in addition to urea and guanidine hydrochloride) in an attempt both to characterize the thermodynamics of the process and to identify conditions that lead to an increase in the population of the folded monomers. Data suggest that sodium perchlorate stabilizes the protein at low concentration (<1.5 M) and destabilizes the protein at higher perchlorate concentration with the formation of a "significantly folded" monomer. The tryptophan residue in the "significantly folded" monomer induced by perchlorate is more exposed to the solvent than in native dimer.

Bacteriophage lambda↗
PubMed2005

Trace level perchlorate analysis by ion chromatography-mass spectrometry.

Perchlorate is commonly used as an oxidant in solid fuel propellant for rockets and missiles. Recently perchlorate contamination was found in many aquifers associated with Colorado River and other sites. Perchlorate was also found at elevated level in crops that use contaminated water for irrigation. Ion chromatography with conductivity detection could be used to measure perchlorate levels in drinking and wastewaters as per United States Environmental Protection Agency method 314, but at lower levels and with complexity of the matrix there could be false positive and/or false negative. This study was done to demonstrate the detection of perchlorate with lower detection limit with high ionic matrix by ion chromatography-mass spectrometry.

Chromatography, Ion Exchange↗
PubMed2006

US Environmental Protection Agency Method 314.1, an automated sample preconcentration/matrix elimination suppressed conductivity method for the analysis of trace levels (0.50 microg/L) of perchlorate in drinking water.

Since 1997 there has been increasing interest in the development of analytical methods for the analysis of perchlorate. The US Environmental Protection Agency (EPA) Method 314.0, which was used during the first Unregulated Contaminant Monitoring Regulation (UCMR) cycle, supports a method reporting limit (MRL) of 4.0 microg/L. The non-selective nature of conductivity detection, combined with very high ionic strength matrices, can create conditions that make the determination of perchlorate difficult. The objective of this work was to develop an automated, suppressed conductivity method with improved sensitivity for use in the second UCMR cycle. The new method, EPA Method 314.1, uses a 35 mm x 4 mm cryptand concentrator column in the sample loop position to concentrate perchlorate from a 2 mL sample volume, which is subsequently rinsed with 10 mM NaOH to remove interfering anions. The cryptand concentrator column is combined with a primary AS16 analytical column and a confirmation AS20 analytical column. Unique characteristics of the cryptand column allow perchlorate to be desorbed from the cryptand trap and refocused on the head of the guard column for subsequent separation and analysis. EPA Method 314.1 has a perchlorate lowest concentration minimum reporting level (LCMRL) of 0.13 microg/L in both drinking water and laboratory synthetic sample matrices (LSSM) containing up to 1,000 microg/L each of chloride, bicarbonate and sulfate.

Chromatography, Liquid↗
PubMed2006

The thyroid endocrine disruptor perchlorate affects reproduction, growth, and survival of mosquitofish.

The perchlorate anion--an oxidizer found in rockets, missiles, some ammunition, flares, airbags, and fireworks--occurs as a contaminant in ground and surface water in many parts of the United States. Its toxic effects include inhibition of thyroid hormone synthesis. To investigate its chronic toxicity, mosquitofish (Gambusia holbrooki) adults and fry were exposed to aqueous sodium perchlorate at 1, 10, and 100mg/L, and growth and reproductive performance (fecundity, eggs/embryos mass, and gonadosomatic index [GSI]) were determined. Five-day acute toxicity tests were also performed. Perchlorate had a stimulatory effect on fecundity, GSI, and egg/embryo mass, at least for some treatments. The LC50 of sodium perchlorate was 404 mg/L. Growth was enhanced at 1mg/L but inhibited at 10mg/L. These results suggest that, at environmentally relevant concentrations, perchlorate does not induce acutely toxic effects but may have mild stimulatory or hormetic effects on fitness parameters in this species.

Animals↗
PubMed2006

Acute and chronic activity of perchlorate and hexavalent chromium contamination on the survival and development of Culex quinquefasciatus Say (Diptera: Culicidae).

Effects of water contamination with perchlorate and hexavalent chromium [Cr (VI)] on the mosquito Culex quinquefasciatus were assessed. The chronic (10-day) LC50s values for perchlorate and chromium were 74+/-8.0 mg/L and 0.41+/-0.15 mg/L, respectively. Relative Growth Index, a measure of growth and mortality rates in a population, was significantly reduced within 5 days for levels of perchlorate as low as 25 mg/L and for levels of chromium as low as 0.16 mg/L. Neither compound altered wing length of surviving adults. In combination, contaminants were synergistic, causing 14% more mortality than predicted. Acute (24-h) LC50 values for perchlorate and Cr (VI) were 17,000+/-3200 and 38+/-1.3 mg/L, respectively. Effects on mosquito larvae in contaminated environments are likely to be observed for Cr (VI) but not for perchlorate, which generally does not occur at levels as high as those shown here to affect larval mosquitoes.

Animals↗
PubMed2005

Enzymes responsible for chlorate reduction by Pseudomonas sp. are different from those used for perchlorate reduction by Azospira sp.

Pseudomonas sp. PDA is an unusual bacterium due to its ability to respire using chlorate under aerobic conditions. The chlorate reductase produced by PDA was shown to be intrinsically different from the enzyme responsible for chlorate and perchlorate [(per)chlorate] reduction produced by Azospira sp. KJ based on subunit composition and other enzyme properties. The perchlorate reductase from strain KJ appeared to have two subunits (100 and 40 kDa) while the chlorate reductase from PDA had three subunits (60, 48, and 27 kDa). N-terminal amino acid sequencing of the 100 kDa protein from strain KJ showed a 77% similarity with the perchlorate reductase alpha subunit from another perchlorate-respiring bacterium, Dechloromonas agitata, while the N-terminus amino acid sequence of the 60 kDa protein from strain PDA did not show a similarity to previously isolated chlorate or perchlorate reductases.

Amino Acid Sequence↗
PubMed2006

Comparison of biotic and abiotic treatment approaches for co-mingled perchlorate, nitrate, and nitramine explosives in groundwater.

Biological and abiotic approaches for treating co-mingled perchlorate, nitrate, and nitramine explosives in groundwater were compared in microcosm and column studies. In microcosms, microscale zero-valent iron (mZVI), nanoscale zero-valent iron (nZVI), and nickel catalyzed the reduction of RDX and HMX from initial concentrations of 9 and 1 mg/L, respectively, to below detection (0.02 mg/L), within 2 h. The mZVI and nZVI also degraded nitrate (3 mg/L) to below 0.4 mg/L, but none of the metal catalysts were observed to appreciably reduce perchlorate ( approximately 5 mg/L) in microcosms. Perchlorate losses were observed after approximately 2 months in columns of aquifer solids treated with mZVI, but this decline appears to be the result of biodegradation rather than abiotic reduction. An emulsified vegetable oil substrate was observed to effectively promote the biological reduction of nitrate, RDX and perchlorate in microcosms, and all four target contaminants in the flow-through columns. Nitrate and perchlorate were biodegraded most rapidly, followed by RDX and then HMX, although the rates of biological reduction for the nitramine explosives were appreciably slower than observed for mZVI or nickel. A model was developed to compare contaminant degradation mechanisms and rates between the biotic and abiotic treatments.

Aniline Compounds↗
PubMedDate not supplied

Development of cultures capable of reducing perchlorate and nitrate in high salt solutions.

An ion exchange process with biological perchlorate and nitrate destruction and reuse of spent regenerant brine has been proposed as an efficient and environmentally sound method to treat perchlorate-contaminated groundwater. A culture capable of reducing perchlorate and nitrate in spent ion exchange regenerant brine containing at least 30 g/L NaCl is needed for this to be feasible. A batch culture inoculated from activated sludge failed to acclimate to more than 15 g/L NaCl whether nitrate was present or not. A mixed culture inoculated from marine sediment was capable of simultaneously reducing 100mg/L perchlorate and denitrifying 500 mg/L nitrate within 5 h in a synthetic medium in the presence of 30 g/L NaCl. The growth conditions to maintain this culture in a healthy state required the addition of trace metals, Na2S, and phosphate. A second culture capable of removing 100 mg/L perchlorate from synthetic medium containing 60 g/L NaCl within 24 h was also developed.

Biodegradation, Environmental↗
PubMed2005

The removal of perchlorate from groundwater by activated carbon tailored with cationic surfactants.

In rapid small-scale column tests, cationic surfactant-tailored activated carbons (ACs) effectively removed perchlorate to below detection levels for up to 30 times longer than virgin AC. By pre-loading bituminous AC with dicocodimethylammonium chloride, tallowtrimethylammonium chloride, cetyltrimethylammonium chloride, or cetylpyridinium chloride, 75 ppb perchlorate was removed for 27,000-35,000 bed volumes before the effluent perchlorate rose above 1 ppb. These tests employed a natural groundwater that also contained 30 mg/L sulfate, 26 mg/L nitrate (as NO3-), and other ions. By the time of 25 ppb perchlorate breakthrough, 7.3-10.1% of quaternary ammonium sites had perchlorate associated with them. Although some of the surfactants leached out of the tailored carbon beds (0.6-21.2% of the amount loaded), the leached surfactant could be removed to below detectable limits with a virgin AC polishing bed that chased the tailored bed.

Adsorption↗
PubMed2005

Simultaneous removal of perchlorate and nitrate from drinking water using the ion exchange membrane bioreactor concept.

This work evaluates the feasibility of the ion exchange membrane bioreactor (IEMB) concept for the simultaneous removal of perchlorate and nitrate from drinking water, when nitrate is present in the ppm range and perchlorate in the ppb range. The IEMB concept combines Donnan dialysis and simultaneous biological degradation of both pollutants. Membrane transport studies showed that Donnan dialysis is suitable for obtaining water with concentrations of perchlorate and nitrate below the recommended levels. However, the pollutants were accumulated in a receiving stream, thus requiring additional treatment before disposal. On the other hand, the IEMB process operated with hydraulic retention times ranging from 1.4 to 8.3h in the water compartment, proved to remove effectively perchlorate and nitrate while preserving the water composition with respect to other ions, thus avoiding secondary contamination of the treated water. For a polluted water stream containing 100 ppb of ClO(4)(-) and 60 ppm of NO(3)(-), the concentrations of both ions in the treated stream were kept below the recommended levels of 4 ppb for ClO(4)(-) and 25 ppm for NO(3)(-). The IEMB system was operated under ethanol limitation, but even under these conditions, an increase of the perchlorate and nitrate concentrations in the treated water was not observed for up to 6 days.

Bioreactors↗
PubMed1987

Investigation of perchlorate, phosphate and ion-pairing eluent modifiers for the separation of cephalosporin epimers.

The retention behavior of several pairs of 7 alpha- and 7 beta-cephalosporin epimers was investigated using perchlorate, phosphate and ion-pairing eluent modifiers. At pH 2.5, sodium perchlorate, sodium phosphate and sodium pentanesulfonate all provided separation of epimers with free 7-amino groups. When the 7-amino group was blocked, as in cephalexin and cefaclor, sodium perchlorate gave the best separation at pH 2.5. A tetrabutylammonium ion-pairing system at pH 7.0 provided separation of all epimer pairs containing a free carboxylic acid at the 3 position. Hydrophobic, residual silanol and ionic interactions were factors in the retention mechanism of the cephalosporins under the conditions investigated. An ionic interaction of perchlorate with the protonated amine of the cephalosporin was postulated as an explanation of the retention and selectivity effects observed with perchlorate as an eluent modifier.

Cephalosporins↗