TOXICOLOGICAL PROFILE FOR CHROMIUM - Davidborowski.com

CHROMIUM 2312. HEALTH EFFECTS2.11 METHODS FOR REDUCING TOXIC EFFECTSThis section will describe clinical practice and research concerning methods for reducing toxic effects ofexposure to chromium. However, because some of the treatments discussed may be experimental andunproven, this section should not be used as a guide for treatment of exposures to chromium. Whenspecific exposures have occurred, poison control centers and medical toxicologists should be consultedfor medical advice. The following text provides specific information about treatment following exposuresto chromium:Nadig RJ. 1994. Cadmium and other metals and metalloids. In: Goldfrank LR, Weisman RS,Flomenbaum NE, et al, eds. Goldfrank's toxicologic emergencies. 5th ed. Norwalk, CT: Appleton andLange,1063-1069.2.11.1 Reducing Peak Absorption Following ExposureGeneral recommendations for reducing absorption of chromium following acute inhalation exposure haveincluded moving the patient to fresh air, monitoring for respiratory distress, and administering humidifiedsupplemental oxygen with assisted ventilation if required (HSDB 1998). The absorption of inhaledchromium compounds depends on such factors as oxidation state, particle size, and solubility.Chromium(VI) passes through the alveolar lining of the lungs to the bloodstream more readily than doeschromium(III) (see Section 2.3.1.1), and more soluble compounds are absorbed more readily than thosethat are less soluble (Bragt and van Dura 1983). Although chromium(VI) is more readily absorbed fromthe lungs than chromium(III), various components of the respiratory system can reduce chromium(VI) tochromium(III), which is far less capable of crossing cell membranes than chromium(VI), thereby reducingthe bioavailability of chromium to target cells (De Flora and Wetterhahn 1989). Epithelial lining fluid(ELF) is capable of reducing chromium(VI) (Petrilli et al. 1986b) and may represent the first line ofdefense against inhaled chromium(VI). Ascorbic acid (vitamin C) and glutathione, both of which werefound to reduce chromium(VI) to chromium(III) in cell-free bronchoalveolar lavage fluid or solublefractions of rat lungs in vitro, appear to be involved in this activity of ELF (Suzuki and Fukuda 1990).Uptake and reduction of chromium(VI) by pulmonary alveolar macrophages, catalyzed by NADH- orNADPH-dependent cytosolic enzyme activities, may lead to virtually irreversible sequestration andefficient removal by mucociliary action (De Flora and Wetterhahn 1989; De Flora et al. 1984, 1987b).Reduction of chromium(VI) within pulmonary alveolar macrophage homogenates was stimulated in ratsby the administration of the glutathione precursor, N-acetylcysteine (De Flora and Wetterhahn 1989). As