Measurement of the Spectral Shape of the ß-Decay of

We report on a comparison between the theoretically predicted and experimentally measured spectra of the first-forbidden nonunique ß-decay transition ^{137}Xe(7/2^{-})→^{137}Cs(7/2^{+}). The experimental data were acquired by the EXO-200 experiment during a deployment of an AmBe neutron source. The ultralow background environment of EXO-200, together with dedicated source deployment and analysis procedures, allowed for collection of a pure sample of the decays, with an estimated signal to background ratio of more than 99 to 1 in the energy range from 1075 to 4175 keV. In addition to providing a rare and accurate measurement of the first-forbidden nonunique ß-decay shape, this work constitutes a novel test of the calculated electron spectral shapes in the context of the reactor antineutrino anomaly and spectral bump.

Search for Neutrinoless Double-ß Decay with the Complete EXO-200 Dataset.

A search for neutrinoless double-ß decay (0νßß) in ^{136}Xe is performed with the full EXO-200 dataset using a deep neural network to discriminate between 0νßß and background events. Relative to previous analyses, the signal detection efficiency has been raised from 80.8% to 96.4±3.0%, and the energy resolution of the detector at the Q value of ^{136}Xe 0νßß has been improved from σ/E=1.23% to 1.15±0.02% with the upgraded detector. Accounting for the new data, the median 90% confidence level 0νßß half-life sensitivity for this analysis is 5.0×10^{25} yr with a total ^{136}Xe exposure of 234.1 kg yr. No statistically significant evidence for 0νßß is observed, leading to a lower limit on the 0νßß half-life of 3.5×10^{25} yr at the 90% confidence level.

Search for Neutrinoless Double-Beta Decay with the Upgraded EXO-200 Detector.

Results from a search for neutrinoless double-beta decay (0νßß) of ^{136}Xe are presented using the first year of data taken with the upgraded EXO-200 detector. Relative to previous searches by EXO-200, the energy resolution of the detector has been improved to σ/E=1.23%, the electric field in the drift region has been raised by 50%, and a system to suppress radon in the volume between the cryostat and lead shielding has been implemented. In addition, analysis techniques that improve topological discrimination between 0νßß and background events have been developed. Incorporating these hardware and analysis improvements, the median 90% confidence level 0νßß half-life sensitivity after combining with the full data set acquired before the upgrade has increased twofold to 3.7×10^{25} yr. No statistically significant evidence for 0νßß is observed, leading to a lower limit on the 0νßß half-life of 1.8×10^{25} yr at the 90% confidence level.

Toxicity study of di(2-ethylhexyl)phthalate (DEHP) in combination with acetone in rats.

In two separate studies with exposure duration 9 weeks or 4 weeks, male Wistar rats were dosed with di(2-ethylhexyl)phthalate (DEHP) by gavage and exposed to drinking water with or without acetone (0.5% wt/v in the 9-week study, 1.0% wt/v in the 4-week study). In the 9-week study the doses of DEHP were 0, 125, 250, 500 or 1000 mg/kg b.wt. In the 4-week study the doses of DEHP were increased to 1000, 5000 and 10,000 mg/kg b.wt. In the 9-week study, the relative liver weight was increased in the rats exposed to 500 and 1000 mg/kg b.wt. No interaction of DEHP and acetone was observed in any of the measured parameters. In the 4-week study DEHP, at the highest dose level, resulted in severe general toxicity. The group exposed to DEHP in combination with acetone was more affected. Male fertility was decreased. Body weight was decreased, and the relative weight of the liver, kidney, heart, brain and adrenals increased. The relative weight of the testes decreased in the 5000 and 10,000 mg/kg b.wt. groups. The weight of seminal vesicles and epididymals decreased at 10,000 mg/kg b.wt. In animals exposed to 5000 and 10,000 mg DEHP/kg b.wt. a severe atrophy of the seminiferous tubules and a slight diffuse Leydig's cell hyperplasia was observed. The cellular debris and conglomerates of desquamated cells found in the lumen of the seminiferous tubules were immunostained positive for vimentin. This indicates that Sertoli cell cytoplasm is included in the conglomerates an interesting finding not previously described. No specific interaction of DEHP and acetone was observed in any of the measured parameters.

Toxicity of the styrene metabolite, phenylglyoxylic acid, in rats after three months' oral dosing.

Male Wistar rats were dosed with 0, 1250, 3750 or 5000 mg/l of phenylglyoxylic acid (PGA) (CAS no. 611-73-4) in the drinking water ad libitum for 3 months. During the entire treatment period, there were no gross signs of toxicity related to PGA. No changes in neurobehavior were found after using a functional observational battery or radial arm maze. An increased relative kidney weight was seen in the highest dose-group (Controls: 0.504 +/- 0.031 g/100 g b.wt.; 5000 mg PGA/l: 0.579 +/- 0.033 g/100 g b.wt.; p<0.01). No other organ weights were affected. Histopathology revealed no change in kidney structure. No changes in clinical biochemistry. In the highest dose-group three animals out of ten showed reduction in peripheral nerve myelin sheath thickness. No such changes were seen in the control group. The study revealed no changes in auditory brain stem response but minor changes in electroretinography. The noradrenaline (NA) concentration decreased in pons and thalamus whereas it increased in medulla oblongata and whole brain. The dopamine (DA) concentration increased in cerebellum, hippocampus, pons, and whole brain. The most marked DA increase was seen in hippocampus (Controls: 0.56 +/- 0.10 nmol/g tissue; 5000 mg/l: 1.04 +/- 0.11 nmol/g tissue; p<0.001). The 5-hydroxytryptamine (5-HT) concentration decreased in cerebellum, cerebral cortex, hippocampus, and medulla oblongata, whereas it increased in thalamus. The yield of synaptosomal protein, synaptosomal NA, DA, and 5-HT concentrations, and DA uptake rate were not affected. When dosed males were mated with naive females, there were no differences between groups in the pregnancy rate, number of corpora luteae, implantations, live or dead fetuses, resorptions, preimplantation loss, or postimplantation loss. It is concluded that a part of the effects on kidney, peripheral nerves, and vision, which have previously been reported after exposure to styrene, might be induced by the styrene metabolite, PGA. If PGA has ototoxic effects in rats, the dosing in the present study is not sufficient to induce the necessary ototoxic concentration in blood. Alternatively, the ototoxicity of styrene, like toluene, may be caused the parent compound itself and not by a metabolite like PGA.

Teratogenicity and in vitro mutagenicity studies on nonoxynol-9 and -30.

Polyoxyethylene alkylphenols (PA) are a group of non-ionic surfactants with a widespread use. As part of the safety evaluation of PA a teratology study with nonoxynol-9 and -30 (NP-9 and NP-30) administered perorally and epicutaneously to rats was performed. In addition the mutagenicity of NP-9 was tested in the Ames test. Treatment of pregnant rats with NP-30 (up to 1 g/kg b.wt./day, orally) did not reveal any signs of adverse effects. Pregnant rats given 250 mg or 500 mg NP-9/kg b.wt./day orally exhibited a statistically significant decrease in weight gain. A concomitant effect in these dams on reproduction, and an increase in the incidence of extra ribs and dilated pelvic cavity in their foetuses was interpreted as a consequence of a toxic effect of high doses of NP-9. No clear cut effect was observed when pregnant rats were dosed epicutaneously with up to 500 mg of NP-9/kg b.wt./day. A slight but persistent response in one tester strain in the Ames test was not interpreted as a clear mutagenic effect of NP-9.

Subchronic oral toxicity of turmeric oleoresin in pigs.

Turmeric oleoresin was fed for 102-109 days to groups of eight pigs (males and females) at dietary levels providing intakes of 60, 296 and 1551 mg/kg body weight/day. Twelve pigs served as controls. The highest dose group showed a reduction in weight gain and in food-conversion efficiency. Statistically significant dose-related increases in the weight of the liver and the thyroid were recorded at all dose levels. Pericholangitis, hyperplasia of the thyroid and epithelial changes in the kidney and urinary bladder were observed in the two higher dose groups. It is questionable whether a no-adverse-effect level can be established on the basis of the observations in this experiment. Further studies should be initiated to elucidate the mechanism of action of turmeric.

Study of toxicity of butylated hydroxyanisole (BHA) in pregnant gilts and their foetuses.

An embryotoxicity study on butylated hydroxyanisole (BHA) was carried out in SPF pigs (Danish Landrace). BHA was incorporated in the diet and administered to pigs in doses of 0, 50, 200 and 400 mg/kg body wt/day from mating (artificial insemination) to day 110 of the gestation period, when the foetuses were removed. Significant lower weight gain was observed in the dams dosed 400 mg/kg body wt/day. Absolute and relative organ weight for the liver and thyroid gland showed a dose-related increase, BHA neither affected the reproduction data nor the incidence of defects in the foetuses.

A short term peroral study of the food colour, Ponceau 6R in pigs.

Ponceau 6R (the tetrasodium salt of 1-(4-sulpho-1-naphthyl-azo)-2-naphthol-3,6,8-trisulphonic acid) was fed to pigs at dietary levels of 0 (control), 100, 500 and 1500 mg/kg body wt./day for 102--105 days. In the 1500-mg group a decrease in weight gain and food utilization was seen, and 1 pig died with a hemolytic anaemia. Dose dependent discolouration was seen of the connective tissue in the groups given 1500 and 500 mg/kg body wt. For this effect the no-effect-level was 100 mg Ponceau 6R/kg body wt. per day.

A study of the embryotoxicity of the food colour Ponceau 4 R in rats.

An embryotoxicity study on Ponceau 4 R was carried out in SPF Wistar rats. The substance was given by gavage from day 1 to 20 of the gestation period in doses of 0, 1000, 2000, and 4000 mg/kg bw per day, dissolved in distilled water. The foetuses were removed on day 21. No effect due to the treatment with the dye was observed with regard to the number of corpora luteae (CL), of implantations, of foetuses dead or alive with regard to gross malformations, to skeletal and internal malformations or to the weight of the foetuses.