Chromium+(hexavalent)

Hexavalent Chromium //Chromium (VI), Cr(VI)//


  Although archeological studies of the Chinese Terracotta Army (buried in the 3rd Century BC) found chromium-coated bronze spear tips, "modern" chromium was found by westerners much later. Chromium ore, known as Siberian Red Lead, was discovered in 1766 by German Johann Gottlob Lehmann. It was difficult to mine and remove its components. Through various scientific studies of the ore, elemental chromium was discovered in 1797 by the French chemist Louis-Nicolas Vaquelin who burned the ore with charcoal (carbon) in a reaction that resulted in the formation of solid chromium crystals.
 * Discovery **

Chromium is used for leather tanning and chrome plating, as well as in pigments for dyes, paints, inks, and plastics. It can also be added to these and other surface coatings as an anti-corrosive agent.    ** Products**  <span style="font-size: 120%; font-family: 'Times New Roman',Times,serif; color: rgb(13, 130, 24);"><span style="font-size: 90%; color: rgb(0, 0, 0);"> <span style="font-size: 120%; font-family: 'Times New Roman',Times,serif; color: rgb(13, 130, 24);"><span style="font-size: 90%; color: rgb(0, 0, 0);">  <span style="font-size: 120%; font-family: 'Times New Roman',Times,serif; color: rgb(13, 130, 24);"><span style="font-size: 90%; color: rgb(0, 0, 0);">  <span style="font-size: 120%; font-family: 'Times New Roman',Times,serif; color: rgb(13, 130, 24);"><span style="font-size: 90%; color: rgb(0, 0, 0);"> <span style="font-size: 120%; font-family: 'Times New Roman',Times,serif; color: rgb(13, 130, 24);"><span style="font-size: 90%; color: rgb(0, 0, 0);"> Chrome plating is commonly used for appliances. <span style="font-size: 120%; font-family: 'Times New Roman',Times,serif; color: rgb(13, 130, 24);"><span style="font-size: 90%; color: rgb(0, 0, 0);"> <span style="font-size: 120%; font-family: 'Times New Roman',Times,serif; color: rgb(13, 130, 24);"><span style="font-size: 90%; color: rgb(0, 0, 0);"> Chromium is used in the creation of stainless steel. <span style="font-size: 120%; font-family: 'Times New Roman',Times,serif; color: rgb(13, 130, 24);"> **Hazards** <span style="font-size: 120%; font-family: 'Times New Roman',Times,serif; color: rgb(13, 130, 24);"> <span style="font-size: 120%; font-family: 'Times New Roman',Times,serif; color: rgb(13, 130, 24);"> <span style="color: rgb(13, 130, 24);"> <span style="font-size: 90%; color: rgb(0, 0, 0);">Chromium is harmful to humans and animals and is a known carcinogen. It can work its way through the environment in a variety of ways, making it hard to track. Chromium tends to settle in soil and water, offering a pleth <span style="font-size: 120%; font-family: 'Times New Roman',Times,serif; color: rgb(13, 130, 24);"><span style="font-size: 90%; color: rgb(0, 0, 0);">ora of ways to come in contact with humans.
 * <span style="font-size: 120%; color: rgb(13, 130, 24);">Uses **

<span style="color: rgb(0, 0, 0);"> People can be exposed to Chromium by doing any of the following: • Ingesting contaminated food or water • Breathing contaminated air or skin contact in the workplace • Living near an uncontrolled waste site
 * <span style="color: rgb(13, 130, 24);"> Exposure **

**Short and Long-Term Health Effects** <span style="color: rgb(0, 0, 0);">While small amounts of chromium are important to plant and animal processes (it assists in the body’s use of sugar, protein, and fat), over-exposure to chromium can cause ulcers and irritation of skin, respiratory and digestive tracts depending on how a person is exposed. It is also a known carcinogen.

**The Erin Brockovich Case** <span style="font-size: 90%; color: rgb(0, 0, 0);">The case of drinking water contamination in Hinkley, California involved a natural gas pipeline lined with hexavalent chromium to prevent corrosion of the cooling tower. Waste water used dissolved the chromium (VI), which was discharged into unlined wastewater ponds. The water with chromium dissolved in it made its way into the groundwater, contaminating the drinking water supply. The concentration of Cr(VI) in the water exceeded the EPA's maximum contaminant level of 0.10 ppm. Residents of Hinkley were experiencing health problems from respiratory failure to cancer, prompting Brockovich's case. In the 1996 settlement, Erin Brockovich won a resounding $333 million, the largest settlement for a direct action lawsuit. The story of the case was made into a blockbuster movie staring Julia Roberts in 2000.