Chromium and its compounds

The substance
Chromium is an odourless, hard, steel-grey coloured metal that takes a high polish. It melts at about 1860 0C. The principal ore is chromite, which is found in Zimbabwe, Russia, South Africa, Turkey, Iran and Finland. All compounds of chromium are coloured. The principal ore from which chromium is extracted is chromite. Chromium has three main valence forms - metallic chromium(0), chromium(III) and chromium(VI). Chromium(III) or trivalent chromium occurs naturally in the environment (e.g. in chromite) and is an essential dietary nutrient. Metallic chromium(0) and chromium(VI) or hexavalent chromium are produced by industrial processes.

Use
The major use of the element chromium is as an essential alloy in stainless steel. Chromium is also used to form many useful high performance alloys, for example for high temperature parts of jet engines. Chromium compounds are used for making bricks in furnaces, as dyes and pigments, for chrome plating, as a chemical catalyst, in leather tanning and wood preserving.

Major emissions
In general, the largest man-made sources of chromium emissions to the environment are chemical manufacturing, the combustion of fossil fuels, waste incineration and steel making. A significant source is also glass production. Since chromium occurs as an element in the earth's crust; releases to the environment also result from natural sources.

Impacts on human health and environment
Excessive exposure to chromium(VI) compounds can lead to health effects and may cause cancer. Some chromium compounds are also toxic to aquatic life; chromium(VI) compounds are more toxic and are readily absorbed by biological systems whereas chromium(III) are less toxic and are not readily absorbed by living species. Certain aquatic species bioaccumulate chromium although fish do not appear to do so. However, hazards depend on the form and bioavailability of chromium.

Certain chromium (VI ) compounds are priority substances under Regulation 793/93. The risk assessment report has been completed and can be downloaded from http://ecb.jrc.it/existing-chemicals/.

Emission to air reporting threshold: 100 kg/year

Emission to water reporting threshold: 50 kg/year

Data source: European Pollutant Emission Register