Registration Dossier

Administrative data

Key value for chemical safety assessment

Additional information

The chemical and physiological properties of the pigment Zircon, cadmium yellow 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 relevant exposure 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 cadmium from the test item Zircon, cadmium yellow at a loading of 0.1g/L after 2 hours was between0.180µg/L (PBS) and 0.398 µg/L (ALF) and between 0.140 µg/L (GMB) - 0.722 µg/L (GST) after 24 hours. Further, the dissolution of zirconium from the test item Zircon, cadmium yellow was in a range ofbelow LODand 0.812 µg/L (ALF) at a loading of 0.1g/L after 2 hours and between below LOD (ASW) - 1.44 µg/L (ALF) after 24 hours.

 

In conclusion, since the dissolved Cd and Zr concentrations from this pigment under simulated physiological conditions were below 2.2 µg/L even at the highest loading of 0.1g/L, corresponding to a solubility of less than 0.003 % after 24 hours, this pigment may reasonably be considered biologically inert.

Justification for classification or non-classification

The chemical and physiological properties of the pigment Zircon, cadmium yellow indicate a very low bioaccessibility of the elements Cd and Zr from the crystalline structure. Thus, the bioavailability via oral, dermal or inhalation exposure routes can be considered as negligible in all media relevant for uptake into the body and also the compartment relevant for distribute within body tissues.

 

No classification for genetic toxicity according to Directive 67/548/EEC and EC Regulation No. 1272/2008 is anticipated.