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INTRODUCTION

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Chromium toxicity results from occupational exposure, environmental exposure, or a combination of both routes. Like many metals, the clinical manifestations of chromium toxicity depend upon whether the exposure is acute or chronic and on the chemical form of chromium. Acute toxicity is more likely to involve multiple-organ failure, whereas chronic exposure is more likely to lead to cancer.

HISTORY AND EPIDEMIOLOGY

Chromium (from the Greek word for color, chroma) is a naturally occurring element that is found in oxidation states of –2 to +6, but it primarily exists in the trivalent (Cr3+) and hexavalent (Cr6+) forms. It was first discovered in 1797 in the form of Siberian red lead (crocoite: PbCrO4), and occurs only in combination with other elements, primarily as halides, oxides, or sulfides (Table 90–1). Elemental chromium (Cr0) does not occur naturally but is extracted commercially from ore. Chromium is found most abundantly in chromite ore (FeCr2O4).7

TABLE 90–1Common Forms of Chromium

Elemental chromium is a blue-white metal that is hard and brittle. It is typically polished to a fine, shiny surface, affords significant protection against corrosion, and added to steel to form stainless steel (an alloy of chromium, nickel, and iron). One of the most important uses of chrome plating is to apply a hard, smooth, surface to machine parts such as crankshafts, printing rollers, ball bearings, and cutting tools. This is known as “hard” chrome plating. Elemental chromium is also used in armor plating safes, and is used in forming brick molds because of its high melting point and moderate thermal expansion.

The carcinogenic potential of hexavalent chromium was first recognized as a cause of nasal tumors in Scottish chrome pigment workers in the late 1800s. In the 1930s, the pulmonary carcinogenicity of hexavalent chromium was first described in German chromate workers.10

PHARMACOLOGY

Chromium is an essential element involved in glucose ...

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