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Toxicological information

Carcinogenicity

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Description of key information

In conclusion, since the dissolved Cr, Fe, Zn and Ni concentrations from this pigment (zinc iron chromite brown spinel) under simulated physiological conditions were below 117 µg/L (in sum) even at the highest loading of 0.1g/L, corresponding to a solubility of less than 0.11 %, this pigment may reasonably be considered biologically inert.

Key value for chemical safety assessment

Additional information

The chemical and physiological properties of the pigment zinc iron chromite brown spinel are characterised by inertness because of the specific synthetic process (calcination at high temperatures, approximately1000°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 1.7), which mimics the very harsh digestion milieu of high acidity in the stomach.

 

The dissolution of chromium from the test item zinc iron chromite brown spinel was below the L.O.Q. and 2.11 µg/L (pH 4.5) at a loading of 0.1g/L after 2 hours and in range of 0.31 µg/L and 5.81 µg/L (pH 4.5 ) after 24 hours. The dissolution of iron from the test item zinc iron chromite brown spinel was in a range of below LoD (pH 6.5) and 15.8 µg/L(pH 1.7) after 2 hours at a loading of 0.1 g/L and in range of below blank and 42.7 µg/L (pH 1.7) after 24 hours. Dissolution of nickel was in range of below L.O.D. (pH 7.4) and 2.71 µg/L (pH 1.7) at a loading of 0.1g/L after 2 hours and in range of below L.O.D. and 6.03 µg/L (pH 4.5).

Dissolution of zinc was in range of below L.O.D. (pH 7.4) and 51.1 µg/L (pH 1.7) at a loading of 0.1g/L after 2 hours and in range of below L.O.D. and 61.8 µg/L (pH 4.5).

 

In conclusion, since the dissolved Cr, Fe, Zn and Ni concentrations from this pigment (zinc iron chromite brown spinel) under simulated physiological conditions were below 117 µg/L (in sum) even at the highest loading of 0.1g/L, corresponding to a solubility of less than 0.12 %, this pigment may reasonably be considered biologically inert.

Justification for classification or non-classification

The chemical and physiological properties of the pigment zinc iron chromite brown spinel 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 carcinogenic effects are expected and no further testing is considered to be required. No classification for carcinogenicity according toDirective 67/548/EEC (basis for REACH) and the future EC Regulation No. 1272/2008 is anticipated.