1453 Chromium(IV) oxide Chromium dioxide or chromium(IV) oxide is a synthetic magnetic substance once widely used in magnetic tape emulsion. With the increasing popularity of CDs and DVDs, the use of chromium(IV) oxide has declined. However, it is still used in data tape applications for enterprise-class storage systems. It is still considered today by many oxide and tape manufacturers to have been the most optimal magnetic recording particulate ever invented. A single study indicates that inhalation exposure to Cr(IV) (as CrO2) does not have significant adverse effect on the blood system. 12018-01-8 CrO2 105.972210 Black crystals. 375°C (decomposes) Oral (L16) ; inhalation (L16) ; dermal (L16) Trivalent chromium may also form complexes with peptides, proteins, and DNA, resulting in DNA-protein crosslinks, DNA strand breaks, DNA-DNA interstrand crosslinks, chromium-DNA adducts, chromosomal aberrations and alterations in cellular signaling pathways. It has been shown to induce carcinogenesis by overstimulating cellular regulatory pathways and increasing peroxide levels by activating certain mitogen-activated protein kinases. It can also cause transcriptional repression by cross-linking histone deacetylase 1-DNA methyltransferase 1 complexes to CYP1A1 promoter chromatin, inhibiting histone modification. Chromium may increase its own toxicity by modifying metal regulatory transcription factor 1, causing the inhibition of zinc-induced metallothionein transcription. (A12, L16, A34, A35, A36) Chromium is absorbed from oral, inhalation, or dermal exposure and distributes to nearly all tissues, with the highest concentrations found in kidney and liver. Bone is also a major storage site and may contribute to long-term retention. Hexavalent chromium's similarity to sulfate and chromate allow it to be transported into cells via sulfate transport mechanisms. Inside the cell, hexavalent chromium is reduced first to pentavalent chromium, then to trivalent chromium by many substances including ascorbate, glutathione, and nicotinamide adenine dinucleotide. Chromium is almost entirely excreted with the urine. (A12, L16) No indication of carcinogenicity (not listed by IARC). (L135) Chromium(IV) oxide is used in magnetic tape emulsion in data tape applications for enterprise-class storage systems. (L525) Chromium in its trivalent state is not very toxic. It may be oxidized to hexavalent chromium, a known carcinogen. Hexavalent chromium has also been shown to affect reproduction and development. (A12) Chromium in its trivalent state is not very toxic, but it may be oxidized to hexavalent chromium. Breathing hexavalent chromium can cause irritation to the lining of the nose, nose ulcers, runny nose, and breathing problems, such as asthma, cough, shortness of breath, or wheezing. Ingestion of hexavalent chromium causes irritation and ulcers in the stomach and small intestine, as well as anemia. Skin contact can cause skin ulcers. (L16) There is no know antidote for chromium poisoning. Exposure is usually handled with symptomatic treatment. (L16) 2009-06-19T21:58:48Z 2014-12-24T20:23:55Z Sulfate transporter (P50443) Sulfate anion transporter 1 (Q9H2B4) (A12) http://en.wikipedia.org/wiki/Chromium(IV)_oxide 48263 C053245 Chromium(IV) oxide true Sulfate transporter (P50443) Sulfate anion transporter 1 (Q9H2B4) (A12) O=[Cr]=O CrO2 InChI=1S/Cr.2O InChIKey=AYTAKQFHWFYBMA-UHFFFAOYSA-N 83.9949 83.930341148 Exogenous Solid 21171202