Soluble Threshold Limit

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)... 

A commercially interesting low calorie fat has been produced from sucrose. Proctor Gamble has patented a mixture of penta- to octafatty acid ester derivatives of sucrose under the brand name Olestra. It was approved by the FDA in January 1996 for use as up to 100% replacement for the oil used in preparing savory snacks and biscuits. Olestra, a viscous, bland-tasting Hquid insoluble in water, has an appearance and color similar to refined edible vegetable oils. It is basically inert from a toxicity point of view as it is not metabolized or absorbed. It absorbs cholesterol (low density Hpoprotein) and removes certain fat-soluble vitamins (A, D, E, and K). Hence, Olestra has to be supplemented with these vitamins. No standard LD q tests have been performed on Olestra however, several chronic and subchronic studies were performed at levels of 15% in the diet, and no evidence of toxicity was found. No threshold limit value (TLV), expressed as a maximum exposure per m of air, has been estabhshed, but it is estimated to be similar to that of an inert hpid material at 5 mg/m. ... 

Orally in rats, the toxicity of sodium tungstate was highest, tungsten trioxide was intermediate, and ammonium tungstate [15855-70-6] lowest (59,60). In view of the degree of systemic toxicity of soluble compounds of tungsten, a threshold limit of 1 mg of tungsten per m of air is recommended. 

Recommendations by the ACGIH are classified as threshold limit values (TLV) based on 8-h TWA. Chromium metal and alloys, Cr(II) compounds and Cr(III) compounds, including chromite ore, have a TLV of 0.5 mg/m Cr in air. Water-soluble Cr(VI) compounds have a TLV of 0.05 mg/m Cr. Certain water-insoluble Cr(VI) compounds, ie, the chromates of 2inc, barium, calcium, lead, strontium, sintered chromic acid, and processing chromite ores, also have a TLV of 0.05 mg/m as well as a human carcinogen designation (145). 

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... 

The maximum threshold limits of metals or metal ions soluble in 0,1 m hydrochloric acid is as follows ... 

On a national basis, Toys require compliance of limits for the same impurities as outlined under food packaging. In particular trace metal amounts have to be considered as well as threshold limits for aromatic amines, soluble in 0,07 m hydrochloric acid. The trace amount of cancerogenic amine should, depending on the various countries, not exceed 5 or 10 ppm. 

The 2003 ACGIH threshold limit valuetime-weighted average (TLV-TWA) for aluminum is lOmg/m for the metal dust, 5 mg/m for pyro powders and welding fumes, as Al, and 2mg/m for the soluble salts and alkyls, as Al. 

The 2003 ACGIH threshold limit value-time-weighted average (TLV-TWA) for barium, and soluble barium compounds, as Ba is 0.5mg/m for barium sulfate it is lOmg/m for total dust containing no asbestos and <1% silica. 

The 2003 ACGIH threshold limit valuetime-weighted averages (TLV-TWAs) are as follows elemental Ni and metal, 1.5mg/m soluble Ni compounds, O.lmg/m insoluble Ni compounds, 0.2mg/m nickel subsulfide,... 

Chick embryos exposed to rhodium on the eighth day of incubation were stunted mild reduction of limb size and feather growth inhibition were also observed. A number of rhodium compounds have tested positive in bacterial assays for genetic altering capability. The 2003 ACGIH threshold limit valuetime-weighted averages (TLV-TWAs) are 1.0 mg/m for the metal, l.Omg/m as Rh, insoluble compounds, and 0.01 mg/m as Rh, soluble compounds. 

Many publishers make available their databases on floppy disks or CD-ROMs, which are often found inside the back cover of the book. An example is the Properties of Organic Compounds (Tide and Milne 1999), which is a CD-ROM list of 27,500 known organic compounds and their formulas, molecular weights, melting points, boiling points, densities, refractive indexes, colors, solubility scales, vapor pressures, and threshold limit values (TLVs) that workers can be exposed to in a normal 8 h workday and 40 h workweek. This reference gives only a limited number of properties, and does not go into flammability or toxicity. Solubility in water is given only as a... 

Tire means by which chemicals enter the body are inhalation (breadiing), ingestion (swallowing), and absorption (skin or living tissue contact). Once in the system these chemicals may produce such symptoms as tissue irritation, rash, dizziness, anxiety, narcosis, headaches, pain, fever, tremors, shortness of breath, birth defects, paralysis, cancer, and death, to mention a few. The amount of chemical diat enters the body is called the "dose." The relationship that defines the body response to the dose given is called the "dose-response curve." The lowest dose causing a detectable response is the "threshold limit." The "limit" is dependent on factors such as particle size of contaminant, solubility, breathing rate, residence time in the system, and human susceptibility. 

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