Soluble threshold limit concentration

Sulfur Polymer Cement. SPC has been proven effective in reducing leach rates of reactive heavy metals to the extent that some wastes can be managed solely as low level waste (LLW). When SPC is combined with mercury and lead oxides (both toxic metals), it interacts chemically to form mercury sulfide, HgS, and lead sulfide, PbS, both of which are insoluble in water. A dried sulfur residue from petroleum refining that contained 600-ppm vanadium (a carcinogen) was chemically modified using dicyclopentadiene and oligomer of cyclopentadiene and used to make SC (58). This material was examined by the California Department of Health Services (Cal EPA) and the leachable level of vanadium had been reduced to 8.3 ppm, well below the soluble threshold limit concentration of 24 ppm (59). 

In California Code of Regulations (CCR) Title 22, the State of California imposes additional requirements for the disposal of waste containing 20 inorganic and 18 organic persistent and bioaccumulative toxic substances (CCR, 1991). Hazardous characteristics of waste streams contaminated with these substances are determined as Total Threshold Limit Concentrations (TTLQ and Soluble Threshold Limit Concentrations (STLC), shown in Appendix 4. 

List of California Toxic Substances, their Soluble Threshold Limit Concentrations and Total Threshold Limit Concentrations... 

STLC denotes Soluble Threshold Limit Concentration. 

Cal 1forni a Soluble threshold limit concentration for wastes 0.25 mg/L CELDS 1992... 

G. Total Threshold Leaching Concentration (TTLC) and Soluble Threshold Limit Concentration (STLC)... 

To protect humans and other mammals, proposed air-quality criteria range from 0.01 to less than 1.0 mg/m3 for metallic nickel and slightly soluble nickel compounds, 0.015-0.5 mg/m3 for water soluble nickel compounds, and 0.005 to 0.7 mg/m3 for nickel carbonyl (Table 6.10). Inhalation of nickel subsulfide concentrations (0.11 to 1.8 mg Ni/m3) near the current threshold limit value of 1 mg Ni/m3 can produce detrimental changes in the respiratory tract of rats after only a few days of exposure (Benson et al. 1995). Additional animal studies are recommended to identify minimally effective inhalation exposure levels for the various nickel compounds (USPHS 1993). Continued monitoring of nickel refining, nickel-cadmium battery manufacture, and nickel powder metallurgy installations is recommended because ambient air levels of bioavailable nickel at these... 

Methoxyflurane (Penthmne) is the most potent inhala-tional agent available, but its high solubility in tissues limits its use as an induction anesthetic. Its pharmacological properties are similar to those of halothane with some notable exceptions. For example, since methoxyflurane does not depress cardiovascular reflexes, its direct myocardial depressant effect is partially offset by reflex tachycardia, so arterial blood pressure is better maintained. Also, the oxidative metabolism of methoxyflurane results in the production of oxalic acid and fluoride concentrations that approach the threshold of causing renal tubular dysfunction. Concern for nephrotoxicity has greatly restricted the use of methoxyflurane. 

Among the possible limitations for the use of NMR as a screening tool, the relative insensitivity of NMR as compared with other spectroscopical methods is the more important. This fact imposes the use of high total compound concentration for the ligand molecules and limits the mixture size that can be tested because of compound solubility, protein precipitation and non-specific binding. We shall see in several examples that this limitation turns out to be inherently less important as the use of new probes and higher fields become available, lowering the threshold of sample concentration to be used in these studies. 

Gels swollen in binary solvents have been the subject of many investigations for their ability to modify the polymer-solvent interaction.4 7 Several authors8 10 have reported that gels made from PNIPA, swollen in aqueous solutions of aromatic compounds, collapse at aromatic concentrations above a certain threshold. This phenomenon has been attributed to the approach of the solubility limit, of the host molecule in water.9... 

Occupational Safety and Health Administration (OSHA) has not identified thresholds for carcinogens that will protect 100% of the population. It usually recommends that occupational exposures to carcinogens be limited to the lowest detectable concentration. To ensure maximum protection from carcinogens through the use of respiratory protection, only the most reliable and protective respirators are recommended. The OSHA permissible exposure limit (PEL) for benzene-soluble fraction of coke oven emissions is 0.150 mg m. ... 

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