Substance fact sheet
The National Pollutant Inventory (NPI) provides information on the types and amounts of pollutants being emitted in the Australian community.
This page provides facts about chromium (III) compounds. It describes how you might be exposed to this substance, how exposure might effect you and the environment, common uses, comparative data about chromium (III) compounds and its physical and chemical properties.
For more information about some of the terms used in this page, see the NPI glossary.
The National Pollutant Inventory (NPI) holds data for all sources of chromium (III) compounds emissions in Australia .
This depends on how much chromium a person has been exposed to, for how long, the nature of the chromium compound(s), and current state of health. Trivalent chromium compounds are considerably less toxic than the hexavalent compounds and are neither irritating nor corrosive under normal conditions. However, all forms of chromium can be toxic at high levels. People who are allergic to chromium may have asthma attacks after breathing high levels of chromium (III) in air. Repeated or prolonged skin contact may cause irritation. In severe cases, skin allergy can occur with itching, redness and/or an eczema-like rash.
Chromium can be inhaled or ingested.
Chromium(III) is an essential nutrient in the diet of humans and animals in very small amounts. Very small amounts of chromium (III) are in everyday foods. Other forms of chromium are not needed by living organisms. The general population is exposed to chromium (III) in food, drinking water and in air. Atmospheric contamination is caused by the combustion of natural gas, oil and coal.
See Sources for more information.
Worksafe Australia :
The eight hour time weighted average (TWA) exposure for chromium (III) compounds (as Cr) is 0.5 mg/m3.
The Australian NOHSC National Exposure Standards Database link is probably the most useful source of information.
Chromium (III) and chromium (VI) both have high chronic toxicity to aquatic life. No data are available on the long-term effects of chromium to plants, birds, or land animals. Chromium (III) has moderate acute toxicity to aquatic life. No data are available on the short-term effects of chromium to plants, birds, or land animals. Fish do not appear to take up or store chromium in their bodies.
Chromium can be transported as particles released into the atmosphere or as dissolved compounds in natural waters.
Chromium (III) can be found in nature and low background levels in air, water and food occur everywhere. Manufacturing, disposal of products or chemicals containing chromium, or burning of fossil fuels release chromium to the air, soil, and water. Chromium particles settle from air in less than 10 days. Chromium sticks strongly to soil particles. Most chromium in water sticks to dirt particles that fall to the bottom and only a small amount of chromium dissolves.
Australian Water Quality Guidelines for Fresh and Marine Waters: (ANZECC, 1992):
Maximum of 0.01 mg/L (i.e. 0.00001 g/L) in fresh waters and 0.05 mg/L (i.e. 0.00005 g/L) in marine waters respectively. Important: These are total chromium concentrations and are based on the assumption that all chromium is in the more toxic chromium (VI) form.
Chromium metal is used as an alloying element to harden steel and to manufacture stainless steel. Chromium compounds are used for chrome plating (e.g. protective coatings for automotive and equipment accessories), as dyes, as inorganic paint pigments, for leather tanning, as fungicides and wood preservatives, and as catalysts. More applications are in the photographic industry (sensitiser), in industrial water treatment (including treatment of cooling tower water), as medicinal astringents and antiseptics, and in nuclear and high temperature research. Chromium (III) compounds are employed as pigment, as catalyst, as tanning agent in the tanning industry, in the production of pure chromium metal and chromium (VI) compounds, and in the production of refractory bricks. More specifically, chromium (III) oxide is used as a paint pigment, a fixative for certain textile dyes and as a catalyst. Chromium (III) acetate is used to fix certain textile dyes, to harden photographic emulsions and as a catalyst. Chromium (III) nitrate is used in the preparation of chrome catalysts, in textile printing operations, and as a corrosion inhibitor. Chromic sulfate is used in tanning, green paints, inks and text dyes and in ceramics.
Emissions to air and water may result from leather tanning industries, chemical manufacturing industries (e.g. dyes for paints, rubber and plastic products), metal finishing industries (e.g. chrome plating), manufacturers of pharmaceuticals, wood, stone, clay and glass products, electrical and aircraft manufacturers, steam and air conditioning supply services, cement producing plants (cement contains chromium), incineration of council refuse and sewage sludge, and combustion of oil and coal.
Chromium may be oxidised and leached from stainless steel into a water-soluble form.
Chromium is a relatively common element, naturally occurring in rocks, soil, plants, animals, and in volcanic dust and gases. Oil and coal contain traces of chromium (III). Chromium is chiefly found as the chromium (III) form in nature, and rarely as chromium (VI) compounds.
Motor vehicle exhaust may contain chromium.
Some textile and some leather products.
Approximately 400 substances were considered for inclusion on the NPI reporting list. A ranking and total hazard score was given based on health and environmental hazards and human and environmental exposure to the substance.
Chromium (III) compounds was ranked as 60 out of 400. The total hazard score taking into account both human health and environmental criteria is 3.2.
On a health hazard rating of 0 - 3 chromium (III) compounds registers 1.2. A score of 3 represents a very high hazard to health, 2 represents a medium hazard and 1 is harmful to health.
On an environmental rating of 0 - 3 chromium (III) compounds registers 2.0. A score of 3 represents a very high hazard to the environment and 0 a negligible hazard.
Factors taken into account to obtain this ranking and these scores include the extent of the material's toxic or poisonous nature and/or its lack of toxicity, and the measure of its ability to remain active in the environment and whether it accumulates in living organisms. It does not take into account exposure to the substance. Environmental exposure is reflected in the NPI rank for this substance (see comparative data below). A substance that scores highly as an environmental hazard is oxides of nitrogen at 3.0 and one of the lower scores is carbon monoxide at 0.8. A substance that scores highly as a health hazard is arsenic at 2.3 and one of the lowest scores is ammonia at 1.0.
| Substance name | Chromium (III) compounds |
| CASR number | 16065-83-1 |
| Molecular formula | Cr3+ |
| Synonyms |
Chromic ion, Chromium ion, Trivalent chromium |
| Physical properties: Chromium is a white, hard, lustrous and brittle metal that is extremely resistant to ordinary corrosive agents. Atomic Number: 24 Properties vary widely depending on the particular compound. Chromic oxide is a bright green hygroscopic powder with melting point of 2435 °C, boiling point of 4000 °C and specific gravity of 5.2. Chromium acetate is a grey-green to blue green pasty mass. Chromium nitrate is a pale green powder. Chromium chloride is a hygroscopic compound with melting point of 1152 °C and specific gravity of 2.8. All chromium compounds have no taste or odour. |
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| Chemical properties: The most stable oxidation state of the element chromium is chromium (III), found in chromite. Chromite is the most important chromium ore mined for the recovery of chromium. Another oxidation state of practical importance is chromium (VI) (CASR# 18540-29-9), but whilst there are some natural sources for chromium (VI), the majority originates from industrial activities. Chromium is chiefly found in its trivalent form in natural environments, except in sea water where chromium in its hexavalent state is prevailing, but at extremely low concentrations. Compared to chromium (III), chromium (VI) is assumed to be about 100 to 1000 times more toxic. Although each form can be converted to the other form under certain conditions, chromium (III) is not oxidised to chromium (VI) in the natural soil environment. Water solubility of chromium and its salts ranges from low to high, e.g chromium (III) oxide is insoluble in water, and chromic (III) acetate, chromium (III) nitrate and chromium (III) sulfate are soluble in water. Pure chromium metal (oxidation state of 0) which dissolves readily in non-oxidising mineral acids such as hydrochloric and sulfuric acids is not found in nature. Chromium (VI) compounds are dealt with elsewhere in the NPI. |
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There is more information that may be useful in understanding some of the issues surrounding the NPI.