Chromium
Chromium is a durable metal used in electroplating, paint pigments (chrome yellow), primers and corrosion inhibitors, wood preservatives, textile preservatives, and leather tanning agents. Chromium exposure may occur by inhalation, ingestion, or skin exposure. Although chromium can exist in a variety of oxidation states, most human exposures involve one of two types: trivalent (eg, chromic oxide, chromic sulfate) or hexavalent (eg, chromium trioxide, chromic anhydride, chromic acid, dichromate salts). Toxicity is associated most commonly with hexavalent compounds; however, fatalities have occurred after ingestion of compounds of either type, and chronic skin sensitivity probably is related to the trivalent form. Chromium picolinate is a trivalent chromium compound often promoted as a body-building agent.
Mechanism of toxicity
Trivalent chromium compounds are relatively insoluble and noncorrosive and are less likely to be absorbed through intact skin. Biological toxicity is estimated to be 10- to 100-fold lower than that of the hexavalent compounds.
Hexavalent compounds are powerful oxidizing agents and corrosive to the airway, skin, mucous membranes, and GI tract. Acute hemolysis and renal tubular necrosis may also occur. Chronic occupational exposure to less soluble hexavalent forms is associated with chronic bronchitis, dermatitis, and lung cancer.
Chromic acid is a strong acid, whereas some chromate salts are strong bases.
Toxic dose
Inhalation. The OSHA workplace permissible exposure limit (PEL, 8-hour time-weighted average) for chromic acid and hexavalent compounds is 0.05 mg/m3 (carcinogen). For bivalent and trivalent chromium, the PEL is 0.5 mg/m3.
Skin.
Related posts:
Full access? Get Clinical Tree
