ACGIH: TWA 0.0002 mg/m3; STEL 0.0005 mg/m3 (Skin)OSHA: Ceiling 0.1 mg/m3NIOSH: IDLH 15 mg/m3; TWA 0.0002 mg/m3
物理描述：
Ammonium dichromate is a bright orange red crystalline solid. It is readily ignited and burns producing a voluminous green residue. If heated in a closed container, the container may rupture due to the decomposition of the material. It may also act as a strong oxidizing agent if mixed with or contaminated with combustible material. It is soluble in water.
颜色/状态：
Solid at 15 °C and 1 atm
气味：
Odorless
稳定性/保质期：
Stable under recommended storage conditions.
自燃温度：
225 °C
分解：
Thermal decomposition is initiated by locally heating to 190 °C, and flame spreads rapidly through the mass.
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)
IDENTIFICATION AND USE: Ammonium dichromate is a solid at 15 °C and 1 atm, forming orange needles. It is not registered for current pesticide use in the U.S., but approved pesticide uses may change periodically and so federal, state and local authorities must be consulted for currently approved uses. It is used as a source of pure nitrogen (especially in the laboratory); in pyrotechnics (Vesuvius fire); in lithography and photo engraving; in special mordant, catalysts, and porcelain finished; intermediate in the manufacturing of pigments; of magnetic recording materials. It is also used as an oxidimentric standard in analytical chemistry. HUMAN EXPOSURE AND TOXICITY: Highly corrosive to skin and mucous membranes. If ingested, violent gastroenteritis with cholera-like stools, peripheral vascular collapse, vertigo, muscle cramps, coma, hemorrhagic diathesis, fever, liver damage & acute renal failure. Methemoglobinemia is probably secondary to intravascular hemolysis. It has been reported in the literature that the ingestion of ammonium dichromate by a child resulted in multiple-organ-system failure and death. Exchange transfusion and hemodialysis were ineffective in removing significant amounts of chromium or causing sustained clinical improvement. In an industrial setting, workers exposed to ammonium dichromate were clinically examined, and 9 of 18 showed dermatitis on the back of the hands and forearms. Three of these workers were transferred and were cured of their dermatitis. ANIMAL STUDIES: Experiments on rats showed inhalation of dust caused edema in perivascular and peribronchial tissue. Ammonium dichromate caused more pronounced changes than did sodium dichromate. ECOTOXICITY STUDIES: Strong irritant. Ammonium toxicity stems from unionized fraction. Chromium will usually be the allergen and limiting factor of the two; Highly toxic by ingestion or inhalation. Threshold concentration for fresh and saltwater fish: 0.05 ppm Cr(VI). Threshold concentration for free ammonia to fish: 0.5 ppm Cr(VI). Toxic to plants.
Hexavalent chromium's carcinogenic effects are caused by its metabolites, pentavalent and trivalent chromium. The DNA damage may be caused by hydroxyl radicals produced during reoxidation of pentavalent chromium by hydrogen peroxide molecules present in the cell. 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)
WEIGHT OF EVIDENCE CHARACTERIZATION: Under the current guidelines (1986), Cr(VI) is classified as Group A - known human carcinogen by the inhalation route of exposure. Carcinogenicity by the oral route of exposure cannot be determined and is classified as Group D. Under the proposed guidelines (1996), Cr(VI) would be characterized as a known human carcinogen by the inhalation route of exposure on the following basis. Hexavalent chromium is known to be carcinogenic in humans by the inhalation route of exposure. Results of occupational epidemiological studies of chromium-exposed workers are consistent across investigators and study populations. Dose-response relationships have been established for chromium exposure and lung cancer. Chromium-exposed workers are exposed to both Cr(III) and Cr(VI) compounds. Because only Cr(VI) has been found to be carcinogenic in animal studies, however, it was concluded that only Cr(VI) should be classified as a human carcinogen. Animal data are consistent with the human carcinogenicity data on hexavalent chromium. Hexavalent chromium compounds are carcinogenic in animal bioassays, producing the following tumor types: intramuscular injection site tumors in rats and mice, intrapleural implant site tumors for various Cr(VI) compounds in rats, intrabronchial implantation site tumors for various Cr(VI) compounds in rats and subcutaneous injection site sarcomas in rats. In vitro data are suggestive of a potential mode of action for hexavalent chromium carcinogenesis. Hexavalent chromium carcinogenesis may result from the formation of mutagenic oxidatitive DNA lesions following intracellular reduction to the trivalent form. Cr(VI) readily passes through cell membranes and is rapidly reduced intracellularly to generate reactive Cr(V) and Cr(IV) intermediates and reactive oxygen species. A number of potentially mutagenic DNA lesions are formed during the reduction of Cr(VI). Hexavalent chromium is mutagenic in bacterial assays, yeasts and V79 cells, and Cr(VI) compounds decrease the fidelity of DNA synthesis in vitro and produce unscheduled DNA synthesis as a consequence of DNA damage. Chromate has been shown to transform both primary cells and cell lines. HUMAN CARCINOGENICITY DATA: Occupational exposure to chromium compounds has been studied in the chromate production, chromeplating and chrome pigment, ferrochromium production, gold mining, leather tanning and chrome alloy production industries. Workers in the chromate industry are exposed to both trivalent and hexavalent compounds of chromium. Epidemiological studies of chromate production plants in Japan, Great Britain, West Germany, and the United States have revealed a correlation between occupational exposure to chromium and lung cancer, but the specific form of chromium responsible for the induction of cancer was not identified ... Studies of chrome pigment workers have consistently demonstrated an association between occupational chromium exposure (primarily Cr(VI)) and lung cancer. Several studies of the chromeplating industry have demonstrated a positive relationship between cancer and exposure to chromium compounds. ANIMAL CARCINOGENICITY DATA: Animal data are consistent with the findings of human epidemiological studies of hexavalent chromium ... /Chromium (VI)/
Evaluation: There is sufficient evidence in humans for the carcinogenicity of chromium(VI) compounds. Chromium(VI) compounds cause cancer of the lung. Also positive associations have been observed between exposure to Chromium(IV) compounds and cancer of the nose and nasal sinuses. There is sufficient evidence in experimental animals for the carcinogenicity of chromium(VI) compounds. Chromium(VI) compounds are carcinogenic to humans (Group 1). /Chromium(VI) compounds/
来源:Hazardous Substances Data Bank (HSDB)
毒理性
致癌性证据
铬 hexavalent 化合物：已知是人类致癌物。/铬 hexavalent 化合物/
Chromium Hexavalent Compounds: known to be human carcinogens. /Chromium hexavalent compound/
Process for preparing chromium(III) oxide, comprising the steps of:
a) Decomposing an alkali metal ammonium chromate double salt at a temperature of 200 to 650° C., especially of 250 to 550° C.,
b) washing the decomposition product obtained after a) and
c) calcining the product obtained after b) at a temperature of 700 to 1400° C., especially of 800 to 1300° C.
制备三价铬氧化物的过程，包括以下步骤：
a) 在200至650°C的温度下分解一种碱金属铵铬酸盐双盐，特别是在250至550°C的温度下进行；
b) 洗涤步骤a)得到的分解产物；
c) 在700至1400°C的温度下煅烧步骤b)得到的产物，特别是在800至1300°C的温度下进行。
CIAHOTNY, KAREL;MACHALEK, PAVEL;PICK, PETR;SIMANEK, JIRI, SB. USCHT PARZE D., 56,(1988) C. 145-172
