Sensitization hexavalent chromium

Unlike nickel, chromium metal does not produce allergic contact dermatitis. Some patients exhibit positive patch tests to divalent chromium compounds, but these compounds are considerably less potent as sensitizers than hexavalent chromium compounds. A case of chromium (chromic) sulfate-induced asthma in a plating worker, confirmed by specific challenge testing and the presence of IgE antibodies, has been reported. ... 

Repeated and prolonged skin contact with cement can result in dermatitis of the hands, forearms, and feet this is a primary irritant dermatitis and may be complicated in some instances by a secondary contact sensitivity to hexavalent chromium. In a study of 95 cement workers, 15 had a mild dermatitis of the hands, which consisted of xerosis with erythema and mild scaling of 20 workers who were patch tested with 0.25% potassium dichromate, one person had a mild reaction and the others were negative. 

Bennicelli C, Camoirano A, Petruzzelli S, et al. 1983. High sensitivity of salmonella TA102 in detecting hexavalent chromium mutagenicity and its reversal by liver and lung preparations. Mutat Res 122 1-5. 

Fowler JF, Kauffman CL, Marks JG, et al. 1999. An environmental hazard assessment of low-level dermal exposure to hexavalent chromium in solution among chromium-sensitized volunteers. J Occup Environ Med 41(3) 150-160. 

Jansen LH, Berrens L. 1968. Sensitization and partial desensitization of guinea pigs to trivalent and hexavalent chromium. Dermatologica 137 65-73. 

Chronic exposure to excess hexavalent chromium results in irritation of the skin and mucous membranes. Exposure to low doses of any form of chromium can induce allergic reactions causing skin rashes and swelling of the skin in sensitive individuals. Ulcerations (or chrome holes) can occur among workers who are exposed to high concentrations of chromic acid, sodium or potassium dichromate or chromate or ammonium dichromate. The ulcers... 

The data of Figure 259 show the temperature sensitivity of an activated catalyst when 02 is removed. The original catalyst contained 0.83 wt% Cr(VI) after activation in dry air at 800 °C. Then the atmosphere was changed to flowing dry N2 at various temperatures. Periodically, the catalyst was sampled to determine the amount of hexavalent chromium it contained. At 350 °C, the catalyst was completely stable in the absence of 02 for 70 h. At 650 °C, however, there was some decomposition, and the catalyst lost about half of its Cr(VI) in 50 h. At 800 °C, the decomposition was rapid, with most of the Cr(VI) being lost in just an hour or two. 

As discussed in Section 7.3.2, hexavalent chromium inhibits the nitrification process in activated sludge. However, organic substrate removal was not affected, which indicated that the various microorganisms might have different sensitivity to chromium (Vankova etal. 1999 Stasinalds etal. 2003). 

Most modern laboratories are nowadays equipped with flame atomic spectrometers, which are routinely used for the quantitative determination of metals in solution. If such equipment is available, detection of metals can be carried out much faster than with the usual wet tests, especially if separations are involved. Usually 1-2 ml solution is consumed during one test however in most cases the tests are so sensitive, that a portion of the original sample solution can be diluted 10-100 fold, leaving enough material for separations. Note that flame atomic spectrometric tests do not provide information about the oxidation state of the metal (e.g. they cannot differentiate between divalent and trivalent iron, trivalent or hexavalent chromium, etc.). ... 

With the exception of two sea urchin samples collected from Puerto Rico, most chromium residues reported in echinoderms have been less than l.Omg/kg DW. The elevated levels of 24.0 and 43.0mg/kg FW of whole organism in Puerto Rican sea urchins are exceptions, which were not reflected in sea cucumber muscle from the same vicinity, and thus should be viewed with caution. Echinoderms from the United Kingdom and environments were comparatively low in chromium concentrations were less than 0.46 mg Cr/kg DW whole organism. Embryos of a sea urchin (Anthocidaris sp.) developed normally in solutions containing 3.2. 2 mg Cr/L, but failed to develop at 8.4-10.0 mg Cr/L. Larvae of another species of sea urchin (Hemicentrotus sp.) were more sensitive, showing abnormal development or dying within 24 h at concenttations of < 1.0 mg Cr/L. Hexavalent chromium at 6.0 mg/L was associated with abnormal development in embryos of Anthocidaris crassispina. 

Detroit and New Orleans. Frequency of chromium dermatitis was highest in constmc-tion workers using cement. Other occupational exposures associated with chromium sensitivity include chromium plating, tanning of leather, application of anticorrosive agents, and printing. Oral ingestion of chromium com-poimds can sometimes lead to skin reactions in sensitive people. Hexavalent chromium com-poimds are more potent inducers and elicitors of skin sensitivity than trivalent chromium compoimds, probably because Cr+ com-poimds can penetrate die skin more readily than Cr+ compoimds. 

A number of metal salts have been found to induce delayed hypersensitivity, mainly of the contact type, in humans or in laboratory animals. Sensitivity to ions of chromium, mercury, platinum, nickel, beryllium, and others seem well established and Table 2 shows some recent findings. The best studied metal sensitizers are the chromium salts, since chromium eczema due to cement is the most important occupational dermatosis (Polak et al. 1973). Hexavalent chromium, in the form of potassium dichromate, is a better sensitizer than trivalent chromium. This seems related to the much better skin penetrating capacity of the dichromate, since numerous studies have shown that trivalent chromium compounds as opposed to hexavalent salt are the actual sensitizers (Polak et al. 1973). The same authors conclude that chromium is probably a component of the determinants formed with autologous carriers and does not produce autoantigens without further participation of the metal ion. In particular, oxidation reactions as generators of determinants seem inoperative in chromium hypersensitivity, since other strong oxidizers like... 

Besides the common inorganic anions (F , CU, Br, NOa , P04 , and S04 ) and cations (Na, K, NH4", Mg " ", and Ca " "), chromate and arsenite are of primary concern because of their greater toxicides as compared to chromium(III) and arsenate, respectively. Hexavalent chromium is a toxic form of chromium that must be monitored in manufacturing wastes. Ion chromatography with postcolumn addition of diphenylcarbazide is probably the most specific and sensitive method available for the determination of hexavalent chromium. 

Hence, cross-sensitivity between trivalent and hexavalent chromium was not convincingly manifested. 

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