Chrome VI

Chrome VI - how many times and at whieh level can it be found on finished produets (leather shoes and garments), or is it only a problem if shoes are disposed as waste and/or burned in certain facilities Levels above 150 ppm have been found on finished products. Nowad s Crlll is used as tanning agent but under certain circumstances it eould be oxidized into CrVt on the product. To avoid this, the tannery must use eertain reducing auxiliaries during production. It is also very important to have a low free Crlll level in the finished product to reduce the risk of CrVl formation. 

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Environment and health-related problems Water-soluble chrome(VI) compounds in the wet cement or mortar have a highly sensitising effect and are up to 90% the cause of allergic cement dermatitis (cement eczema, bricklayer s itch ). The high alkalinity (pH = 13) of cement aids the development of this contact eczema. Bricklayer s itch is one of the most frequent professional diseases in the construction industry. 

The manufacturers of a mass product that is far from the end-user, such as cement or concrete, are under extreme price competition and slightest changes in, say, the cost stracture can be decisive. Elimination of water-soluble chrome-VI compounds that cause chromate-induced eczema would only increase the price of the product minimally. And even if the severe price competition did in fact permit this increased margin (which is highly probable in this example), there has been no significant iimovation push. Uirfortunately, this occupational disease is hardly perceived by the public and the costs incurred by this type of eczema evidently can be externalised by the cement industry (and covered by the employer s liability insurance). 

The coulometry methods based on the physical law which sets the link between the weights of turned electricity and quantity of spent electricity. In many cases the electro generated coulometrical titrate enters in the oxidation process with organic substratum on the mechanism of reaction with the electron carriers. The most effective carriers ate the variable valence metals ions and its components oxidants—chrome (VI), manganese (III), cobalt (III), cerium (IV), vanadium (V), copper (II) deoxidants—cobalt (II), chrome (II), vanadium (HI), titanium (III), iron (II), copper (I), tin (II). The wide area of practical use of the halide ions (chloride-, bromide-, iodide-ions) highlights them apart Ifom a number of reagents—electron carriers. Halide—ions are... 

Dichromate anions are readily absorbed under acidic conditions by wool that has been dyed with chrome dyes. The chromium(VI) on the fibre is then gradually reduced by the cystine residues in wool keratin to chromium(III) cations, which react with the dye ligands to form a stable complex. In this way the cystine disulphide bonds are destroyed, resulting in oxidative degradation of the wool fibres [71]. 

Besides routine laboratory equipment (see section 6.1.4.1, subheading Instrumentation ), a VIS photospectrometer for quantitative detection at 550 nm of ferrocyto-chrome c is required. 

Benzoylphenylhydroxylamine (17 R1 = R2 = Ph) forms complexes with V, Sn, Ti and Zr in 5 to 9 M HC1 but only that of vanadium is extractable into chloroform, permitting a selective determination of that element in chrome ores. A-Cinnamoyl-V-phenylhydroxylamine is even more sensitive. In less acid solutions solvent extractable complexes are formed with a number of other cations and, for example, an orange-red complex of uranium(VI) is extracted by V-benzoyl-iV-phenylhydroxylamine into chloroform.52... 

Acute inhalation LC50 values for chromium trioxide were 87 and 137 mg chromium(VI)/m3 for female and male rats, respectively (American Chrome and Chemicals 1989). Female rats were more sensitive than males to the lethal effects of most chromium(VI) compounds except sodium chromate, which was equally toxic in both sexes. Signs of toxicity included respiratory distress, irritation, and body weight depression (Gad et al. 1986). The LC50 values are recorded in Table 2-1 and plotted in Figure 2-1. 

Dyspnea, cough, and wheezing were reported in two cases in which the subjects inhaled "massive amounts" of chromium(VI) trioxide. Marked hyperemia of the nasal mucosa without nasal septum perforation was found in both subjects upon physical examination (Meyers 1950). In a chrome plating plant where poor exhaust resulted in excessively high concentrations of chromium trioxide fumes,... 

Hepatic Effects. Chromium(VI) has been reported to cause severe liver effects in four of five workers exposed to chromium trioxide in the chrome plating industry. Derangement of the cells in the liver, necrosis, lymphocytic and histiocytic infiltration, and increases in Kupffer cells were reported. Abnormalities in tests for hepatic dysfunction included increases in sulfobromophthalein retention, gamma globulin, icterus, cephalin cholesterol flocculation, and thymol turbidity (Pascale et al. 1952). In a cohort of 4,227 workers involved in production of stainless steel from 1968 to 1984, excess deaths were observed from cirrhosis of the liver compared to expected deaths (0/E=55/31.6) based on national rates and matched for age, sex, and calender time having an SMR of 174 with confidence limits of 131-226 (Moulin et al. 1993). No measurements of exposure were provided. Based on limited information, however, the production of chromium compounds does not appear to be associated with liver effects. As part of a mortality and morbidity study of workers engaged in the manufacture of chromium(VI) compounds (84%) and chromium(III) compounds (16%) derived from chromium(VI) in Japan, 94 workers who had been exposed for 1-28 years were given a complete series of liver function... 

Studies of renal function in chrome platers, whose exposure is mainly to chromium(VI) compounds, have also yielded equivocal results. A positive dose-response for elevated urinary levels of p2-microglobulin was found in chrome platers who were exposed to 0.004 mg chromium(VI)/m3, measured by personal air... 

Occupational exposure to chromium(VI) compounds in a number of industries has been associated with increased risk of respiratory system cancers, primarily bronchogenic and nasal. Among the industries investigated in retrospective mortality studies are chromate production, chromate pigment production and use, chrome plating, stainless steel welding, ferrochromium alloy production, and leather tanning. 

Studies of chromate production workers, who are exposed to a variety of chromium compounds both hexavalent and trivalent, and chromate pigment industries, where exposure is mainly to chromium(VI), have consistently demonstrated an association with respiratory system cancer. Studies in chrome platers, who are exposed to chromium(VI) and other agents, including nickel, generally support the conclusion that certain chromium(VI) compounds are carcinogenic. Studies in stainless steel welders exposed to chromium(VI) and other chemicals, and in ferrochromium alloy workers, who are exposed mainly to chromium(O) and chromium(III), but also to some chromium(VI), were inconclusive. Studies in leather tanners, who are exposed to chromium(III), were consistently negative. 

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