Poisoning significance

Proudfoot AT, Stewart MS, Eevitt T, Widdop B. Paraquat poisoning significance of plasma-paraquat concentrations. Lancet 1979 2 330-332. 

Cr poisoning Significant Not seen in early stage but causes various ... 

Because of the risk of lead poisoning, the exposure of children to lead-based paint is a significant public health concern. The first step in the quantitative analysis of lead in dried paint chips is to dissolve the sample. Corl evaluated several dissolution techniques. " In this study, samples of paint were collected and pulverized with a Pyrex mortar and pestle. Replicate portions of the powdered paint were then taken for analysis. Results for an unknown paint sample and for a standard reference material, in which dissolution was accomplished by a 4-6-h digestion with HNO3 on a hot plate, are shown in the following table. 

Sweetening. Another significant purification appHcation area for adsorption is sweetening. Hydrogen sulfide, mercaptans, organic sulfides and disulfides, and COS need to be removed to prevent corrosion and catalyst poisoning. They ate to be found in H2, natural gas, deethanizer overhead, and biogas. Often adsorption is attractive because it dries the stream as it sweetens. 

Toxicity. Sodium fluoroacetate is one of the most effective all-purpose rodenticides known (18). It is highly toxic to all species of rats tested and can be used either in water solution or in bait preparations. Its absence of objectionable taste and odor and its delayed effects lead to its excellent acceptance by rodents. It is nonvolatile, chemically stable, and not toxic or irritating to the unbroken skin of workers. Rats do not appear to develop any significant tolerance to this compound from nonlethal doses. However, it is extremely dangerous to humans, to common household pets, and to farm animals, and should only be used by experienced personnel. The rodent carcasses should be collected and destroyed since they remain poisonous for a long period of time to any animal that eats them. 

Great care must be exercised ia the preparation and use of Ziegler-Natta catalysts. They are easily poisoned by moisture, among other things. They are pyrophoric and are used ia conjunction with large amounts of flammable monomer and solvent, and so can present a significant safety hazard. 

Rhenium oxides have been studied as catalyst materials in oxidation reactions of sulfur dioxide to sulfur trioxide, sulfite to sulfate, and nitrite to nitrate. There has been no commercial development in this area. These compounds have also been used as catalysts for reductions, but appear not to have exceptional properties. Rhenium sulfide catalysts have been used for hydrogenations of organic compounds, including benzene and styrene, and for dehydrogenation of alcohols to give aldehydes (qv) and ketones (qv). The significant property of these catalyst systems is that they are not poisoned by sulfur compounds. 

Sodium nitrite is poisonous and prolonged contact with dry sodium nitrite or its solutions can cause irritation to the skin, eyes, and mucous membranes. The LD q (oral, rat) is 85 mg per kg body weight (11). Inhalation or ingestion of significant quantities of dust or mist may result in acute toxic effects such as nausea, cyanosis, and low blood pressure, which can lead to possible coUapse, coma, and even death. 

Medical Uses. A significant usage of chelation is in the reduction of metal ion concentrations to such a level that the properties may be considered to be negligible, as in the treatment of lead poisoning. However, the nuclear properties of metals may retain then full effect under these conditions, eg, in nuclear magnetic resonance or radiation imaging and in localizing radioactivity. 

Occasional brief contacts of Hquid carbon tetrachloride with unbroken skin do not produce irritation, though the skin may feel dry because of removal of natural oils. Prolonged and repeated contacts may cause dermatitis, cracking of the skin, and danger of secondary infection. Carbon tetrachloride is apparenfly absorbed through the skin but at such a slow rate that there is no significant hazard of systemic poisoning in normal industrial operations. 

Eor shifting coal-derived gas, conventional iron—chromium catalysts can be used. Because coal gas has a significantly higher concentration of carbon monoxide than is found in gas streams in conventional refineries, the catalyst must be able to withstand high thermal loads. However, potential catalyst poisons such as phenol and other hydrocarbons are not a concern in entrained-bed gasifiers. 

Organic chloride and cycle diluent specifications are less critical since the flows are significantly less. The organic chloride specifications must prevent gross contamination as weU as the potential of soHds that would lead to plugging. The cycle diluent must also be free of gross contamination as weU as significant catalyst poisons such as sulfur (170). 

There are situations where thermal oxidation may be preferred over catalytic oxidation for exhaust streams that contain significant amounts of catalyst poisons and/or fouling agents, thermal oxidation may be the only technically feasible control where extremely high VOC destmction efficiencies of difficult to control VOC species are required, thermal oxidation may attain higher performance and for relatively rich VOC waste gas streams, ie, having >20 25% lower explosive limit (LEL), the gas stream s explosive properties and the potential for catalyst overheating may require the addition of dilution air to the waste gas stream (12). 

Install automatic or manual activation of bottom discharge valve to drop batch into a dump tank with diluent, poison, or inhibitor, or to an emergency containment area (May not be effective for systems such as polymerization reactions where there is a significant increase in viscosity.)... 

Mercury is used in the manufacture of thermometers, barometers and switchgear, and in the production of amalgams with copper, tin, silver and gold, and of solders. A major use in the chemical industry is in the production of a host of mercury compounds and in mercury cells for the generation of chlorine. Mercury has a significant vapour pressure at ambient temperature and is a cumulative poison. 

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