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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

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Administrative data

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Description of key information

Key value for chemical safety assessment

Additional information

In vitro release studies with chromium carbide, Cr metal, and Cr2O3 show that the release rate of Cr into different artificial body fluids is very low, and therefore the bioaccessibility is also low. No studies were available on the toxicokinetics of trichromium dicarbide. Therefore, available studies with chromium metal, chromium(III) oxide and other chromium(III) salts have been used in this dossier. Other chromium(III) salts are more soluble than chromium carbide, but it can be assumed that the kinetic behaviour is quite similar.

Absorption of chromium in the body is largely dependent on chromium species. Intratracheal studies on chromium(III)oxide show that lung clearance of these insoluble chromium compounds is slow. The elimination half-life was 11 days in sheep administered chromium(III) oxide and 6 months in rats after intratracheal administration of chromite particles. No studies on gastrointestinal absorption is available on poorly soluble chromium(III))species, but even soluble chromium(III)chloride is absorbed only at the levels of <2% from the GI-tract. Thus, the oral absorption of chromium carbide is likely to be very low, due to the practically insoluble nature of the substance. The dermal absorption of chromium metal has been tested by in vitro models, and has been shown to be very low.

In the blood plasma, most of the chromium is bound to large molecular mass proteins (e. g. transferrin). Chromium associates also with the oligopeptide low-molecular-weight chromium-binding substance (chromodulin). In blood, chromium is mostly (about 95%) bound to large molecular weight plasma proteins and only a minor part of the chromium can be found in erythrocytes.

The administered Cr is mainly distributed into the liver, kidneys, spleen and bone. Some Cr may also reach the interstitium of the testis, and it may accumulate in the placenta. Only low amounts have been shown to cross the placenta. Many of these toxicokinetic studies were done with CrCl3, which is much more soluble than chromium carbide. Therefore, the absorption of this substance is much higher than that of the practically insoluble chromium carbide and the systemic distribution of trichromium dicarbide likely to be significantly lower.

The excretion of absorbed chromium(III) occurs mainly in the faeces, and to a low extent in the urine.