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At least 1,063 records · Page 59Linked to original sources
PubMed2006

Screening high-fluoride and high-arsenic drinking waters and surveying endemic fluorosis and arsenism in Shaanxi province in western China.

The objectives of this study were to screen high-fluoride and high-arsenic drinking waters, to evaluate the effectiveness of fluoride-reducing projects and to assess the present condition of endemic fluorosis and arsenism in Shaanxi province in western China. For screening high-fluoride drinking waters, five water samples were collected from each selected village where dental fluorosis patients were detected in 8-12 year-old children. For evaluating the effectiveness of fluoride-reducing projects, four water samples were collected from each project at end-user level. Fluoride concentrations in water samples were measured by fluoride-selective electrode method or spectrophotometry. Dental fluorosis in children aging 8-12 years was examined according to Horowitz's Tooth Surface Index of Fluorosis. Skeletal fluorosis in adults was detected clinically and radiologically according to Chinese Criteria of Clinical Diagnosis of Skeletal Fluorosis. For screening high-arsenic waters, 20 water samples were collected from each village which was selected from areas characterized by the geographic features to induce high-arsenic underground water, i.e., alluvial plains, ore mining or smelting areas, geothermal artesians, and thermal springs. Arsenic concentrations in water samples were determined by spectrophotometry or arsine generation atomic fluorospectrophotometry. Arsenism in adults aging 40-89 years was examined in villages with arsenic concentrations in drinking water above 0.05 mg/l according to Chinese Criteria for Classification of Endemic Arsenism Areas and Clinical Diagnoses of Endemic Arsenism. The results showed that the fluoride level of 7144 water samples was 1.17 +/- 0.93 mg/l. There were 3396 (47.6%) high-fluoride waters (fluoride level was above 1.0 mg/l) distributing in 786 (45.1%) villages, where about 0.8 million (50.0%) people inhabited. Additionally, the 1315 fluoride-reducing projects were studied. The fluoride level of the projects was 2.79 +/- 1.09 and 0.98 +/- 0.47 mg/l before and after building the projects, which remained at relatively lower level (1.03 +/- 0.47 mg/l). But there were still 58.0% of the projects providing drinking waters with fluoride concentrations beyond 1.0mg/l. The rates of dental fluorosis and skeletal fluorosis were 38.2% and 11.8%, respectively. The arsenic level of 1732 water samples was 0.010 +/- 0.082 mg/l. There were 174 (14.9%) high-arsenic waters (arsenic level was above 0.010 mg/l) being detected, distributing in 41 (38.7%) villages. The arsenic level in 53 (4.5%) water samples was beyond 0.025 mg/l. There were 3 villages with arsenic level in drinking water beyond Chinese National Permissible Limits (0.050 mg/l), and the prevalence rate of arsenism reached 37.0% in these three villages, 3.7%, 22.2%, and 11.1% of subjects suffering from mild, moderate, and severe arsenism, respectively. Conclusively, the wide distribution of high-fluoride drinking waters contributes to the prevalence of dental and skeletal fluorosis in Shaanxi province and the quality of fluoride-reducing projects should be further improved. Ore mining and smelting induces high-arsenic drinking waters, resulting in arsenism prevalence in Shang-luo city. Proper measures should be taken to deal with water pollution in the ore mining and smelting areas in order to solve the high-arsenic water problem in Shaanxi province.

Adult↗
PubMed1960

A note on the demyelination produced in hens by dialkylfluoridates.

Hens were treated with organophosphorus compounds until signs of neurotoxicity developed. The sciatic nerves, spinal cord, and medulla were then examined histologically by the Marchi method, to determine the extent and distribution of demyelination. The lesions were proportional to the dose of compound injected, and the spinal cord was more sensitive than the sciatic nerves. It is suggested that the spinal cord, and not the sciatic nerves, is the main site of damage in clinical paralysis following dyflos poisoning.

Animals↗
PubMed1989

[Poisoning with a wood preservative].

Autopsy findings and the results of chemical-toxicological analysis are presented on a case of suicide with a wood preservative containing potassium fluoride. The highest amounts of fluoride were found in kidney and urine; there was no increase of fluorides amount in the brain. The analysis was done by colorimetry after micro-diffusion.

Cause of Death↗
PubMed1984

Late preventive effects of phenylmethylsulfonyl-fluoride on carbon tetrachloride-induced liver necrosis.

The administration to rats of phenylmethylsulfonylfluoride (PMSF) 6 or 10 h after tetrachloride (CCl4) significantly prevented liver necrosis induced by this hepatotoxin at 24 h but not at 72 h. Preventive effects of PMSF were not due to interference with CCl4 absorption from the peritoneum since CCl4 levels in livers of treated and untreated animals were not significantly different. The present and previous results from our laboratory suggest that degradative processes mediated by proteases and esterases might play a role in late reversible stages of CCl4-induced liver cell injury.

Animals↗
PubMed1997

New method for retrospective detection of exposure to organophosphorus anticholinesterases: application to alleged sarin victims of Japanese terrorists.

With regard to detection of exposure to anticholinesterase, the presently used methods have the disadvantage that they cannot detect either low-level exposures with certainty or the structure of the agent and the extent of poisoning. In principle, organophosphate-inhibited butyrylcholinesterase in human plasma is the most persistent and abundant source for biomonitoring of exposure to organophosphate anticholinesterases. Fluoride ions reactivate the inhibited enzyme readily at pH 4, converting the organophosphate moiety into the corresponding phosphofluoridate. Subsequent quantitation of the latter product provides a reliable, highly sensitive and retrospective method for detection of exposure to, or handling of, organophosphates such as nerve agents and organophosphorus pesticides. We applied the new procedure to serum samples from victims of the Tokyo subway attack by the AUM Shinriyko sect and from an earlier incident at Matsumoto. In serum of 10 of 11 victims from the Tokyo incident and of 2 of the 7 samples from the Matsumoto incident, reactivation with fluoride ions yielded sarin concentrations in the range of 0.2-4.1 ng/ml serum. Evidently, these victims had been exposed to an organophosphate with the structure PriO(CH3)P(O)X, presumably with X = F (sarin). Several applications of the new procedure to establish nerve agent and/or organophosphate (OP) pesticide exposure can be envisaged, e.g., (i) in biomonitoring of exposure for health surveillance of those handling organophosphates, (ii) in cases of alleged exposure to nerve agents and/or OP pesticides in armed conflict situations or terrorist attacks, (iii) in medical treatment of intoxication, and (iv) in forensic cases against suspected terrorists that may have handled anticholinesterases.

Cholinesterase Inhibitors↗
PubMed2004

Carbonic anhydrase inhibitors: inhibition of the membrane-bound human isozyme IV with anions.

The membrane-associated human isozyme of carbonic anhydrase, hCA IV, has been investigated for its interaction with anion inhibitors, for the CO(2) hydration reaction catalyzed by this enzyme. Surprisingly, halides were observed to act as potent hCA IV inhibitors, with inhibition constants in the range of 70-90 microM, although most of these ions, and especially fluoride, the best hCA IV inhibitor among the halides, are weak inhibitors of other isozymes, such as hCA I, II and V. The metal poisons cyanate, cyanide and hydrogen sulfide were weaker hCA IV inhibitors (K(i)'s in the range of 0.6-3.9 mM), whereas thiocyanate, azide, nitrate and nitrite showed even weaker inhibitory properties (K(i)'s in the range of 30.8-65.1 mM). Sulfate was a good hCA IV inhibitor (K(i) of 9 mM), although it is a much weaker inhibitor of isozymes I, II, V and IX. Excellent hCA IV inhibitory properties showed sulfamic acid, sulfamide, phenylboronic acid and phenylarsonic acid, with K(i)'s in the range of 0.87-0.93 microM, whereas their affinities for the other investigated isozymes were in the millimolar range. The interaction of some anions with the mitochondrial isozyme hCA V has also been investigated for the first time here. It has been observed that among all these isozymes, hCA V has the lowest affinity for bicarbonate and carbonate (K(i)'s in the range of 82-95 mM), which may represent an evolutionary adaptation of this isozyme to the rather alkaline environment (pH 8.5) within the mitochondria, where hCA V plays important functions in some biosynthetic reactions involving carboxylating enzymes (pyruvate carboxylase and acetyl coenzyme A carboxylase). There are important differences of affinity for anions between the two membrane-associated isozymes, hCA IV and hCA IX.

Anions↗
PubMed2004

Abatement of sulfur hexafluoride emissions from the semiconductor manufacturing process by atmospheric-pressure plasmas.

Sulfur hexafluoride (SF6) is an important gas for plasma etching processes in the semiconductor industry. SF6 intensely absorbs infrared radiation and, consequently, aggravates global warming. This study investigates SF6 abatement by nonthermal plasma technologies under atmospheric pressure. Two kinds of nonthermal plasma processes--dielectric barrier discharge (DBD) and combined plasma catalysis (CPC)--were employed and evaluated. Experimental results indicated that as much as 91% of SF6 was removed with DBDs at 20 kV of applied voltage and 150 Hz of discharge frequency for the gas stream containing 300 ppm SF6, 12% oxygen (O2), and 40% argon (Ar), with nitrogen (N2) as the carrier gas. Four additives, including Ar, O2, ethylene (C2H4), and H2O(g), are effective in enhancing SF6 abatement in the range of conditions studied. DBD achieves a higher SF6 removal efficiency than does CPC at the same operation condition. But CPC achieves a higher electrical energy utilization compared with DBD. However, poisoning of catalysts by sulfur (S)-containing species needs further investigation. SF6 is mainly converted to SOF2, SO2F4, sulfur dioxide (SO2), oxygen difluoride (OF2), and fluoride (F2). They do not cause global warming and can be captured by either wet scrubbing or adsorption. This study indicates that DBD and CPC are feasible control technologies for reducing SF6 emissions.

Air Pollutants↗