Hematite, chromium green black

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Endpoint conclusion

Endpoint conclusion:

no study available

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The chemical and physiological properties of the pigment hematite chromium green black are characterised by inertness because of the specific synthetic process (calcination at high temperatures, approximately 1000°C), rendering the substance to be of a unique, stable crystalline structure in which all atoms are tightly bound and not prone to dissolution in environmental and physiological media. This manufacturing process leads to a very low bioaccessibility of the elements contained in the pigment. This has been investigated experimentally in vitro by simulating dissolution under physiological conditions considered to mimic the most relevantexposure routes (oral, dermal and inhalation), as follows:

 

1.) Gamble’s solution (GMB, pH 7.4) which mimics the interstitial fluid within the deep lung under normal health conditions,

2.) phosphate-buffered saline (PBS, pH 7.2), which is a standard physiological solution that mimics the ionic strength of human blood serum,

3.) artificial sweat (ASW, pH 6.5) which simulates the hypoosmolar fluid, linked to hyponatraemia (loss of Na+ from blood), which is excreted from the body upon sweating,

4.) artificial lysosomal fluid (ALF, pH 4.5), which simulates intracellular conditions in lung cells occurring in conjunction with phagocytosis and represents relatively harsh conditions and

5.) artificial gastric fluid (GST, pH 1.5), which mimics the very harsh digestion milieu of high acidity in the stomach.

 

 The dissolution of chromium from the test item hematite chromium green black was below the L.O.D at a loading of 0.1g/L after 2 and 24 hours. Further, the dissolution of aluminium from the test item hematite chromium green black was in a range of <1 (pH 7.4) and 8.6 ug/L (pH 1.5) and below 10 ug/L at a loading of 0.1g/L after 2 and 24 hours.

 

In conclusion, since the dissolved Cr and Al concentrations from this pigmentunder simulated physiological conditionswere below 10 ug/L even at the highest loading of 0.1g/L, corresponding to a solubility of less than 0.01 %, this pigment may reasonably be considered biologically inert.

Justification for classification or non-classification

The chemical and physiological properties of the pigment hematite chromium green black are characterised by inertness because of the specific synthetic process (calcination at high temperatures, approximately 1000°C), rendering the substance to be of a unique, stable crystalline structure in which all atoms are tightly bound and not prone to dissolution in environmental and physiological media. Bioavailability which is the basis for the oral, dermal or inhalation exposure route is not given. In consequence, this substance may reasonably be considered inert in all media relevant for uptake into the body and also the compartment relevant for distribute within body tissues. Hence, no genetic toxicity effects are expected and no further testing is considered to be required. No classification for genetic toxicity according to EC Regulation No. 1272/2008 is anticipated.