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chromium and compounds of chromium

SPRI Emission Reporting Threshold
10.0 Kg/yr Pollutant Emissions to Air
20.0 Kg/yr Pollutant Emissions to Water
20.0 Kg/yr Pollutant Emissions to Waste Water
50.0 Kg/yr Pollutant Emissions to Land
This sheet is a generic summary, designed to give the reader a basic level of background information about the substance in question. Great care has been taken to represent as effectively and correctly as possible the broad range of (not necessarily consistent) information which is available from a variety of sources. The reader must accept therefore that this sheet has no legal status and cannot be relied upon in any legal proceedings. SEPA disclaims any responsibility or liability whatsoever for errors and omissions in this sheet.
What is it?
Pure chromium is produced mainly from the naturally occurring ore "chromite". It is a hard steel-grey coloured metal which can be highly polished. It has a high melting point (1860 degrees celsius). Chromium forms compounds with various chemical valencies (0, III, VI) - many of which are highly coloured.
What is it used for?
Chromium is an essential part of stainless steel. It is also a part of other specialised alloys (mixtures of metals), such as those used in the high temperature parts of jet engines. Compounds of chromium are used to make bricks, in dyes and pigments, for chrome plating, in leather tanning and for wood preserving.
Where does it come from?
The main releases of chromium are from chemical manufacture, the combustion of fossil fuels, incineration of waste, in the production of iron and steel and during glass production. Smaller amounts are also released naturally from the earth's crust.
How might it affect the environment?
Exposure to certain levels of chromium compounds may be toxic to some species of wildlife. Some aquatic species (but not fish) accumulate chromium. Chromium (VI) compounds are more readily absorbed and more highly toxic than chromium (III) compounds. No significant effects on the global environment are expected.
How might exposure to it affect human health?
Pure chromium metal and alloys containing chromium are non-toxic and non-carcinogenic. Exposure to normal (low) environmental concentrations of chromium compounds is unlikely to harm human health. However, inhalation of high levels of chromium (VI) compounds following an accidental release or in occupational settings may damage the lungs (including causing lung cancer). It may also damage the liver, kidneys, intestines or stomach. Chromium (III) compounds are much less toxic and non-carcinogenic, even at high levels.
What steps are being taken to limit the potential impacts?
UK (including Scottish) legislation controlling releases of chromium are those concerned with classification of dangerous substances released to surface waters; and the pollution prevention and control regulations. European Directives covering pollution of aquatic environment by dangerous substances (76/464) control chromium releases to water bodies. International control is through the OSPAR convention for the protection of marine environment of the north-east Atlantic.