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Diss Factsheets

Administrative data

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

In conclusion, since the dissolved Zr and Fe concentrations from this pigment (zirconium zircon with encapsulated hematite) under simulated physiological conditions were below 67.1 µg/L and 25.4 µg/L respectively, even at the highest loading of 0.1g/L, referring to a solubility of 0.07 % and 0.03 %, the pigment is considered biologically inert.


Testing in bacteria reverse mutation assays, although of limited relevance for metals (HERAG, 2007), yielded negative results.

Additional information

The chemical and physiological properties of the pigment zirconium zircon with encapsulated hematite 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 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 Zr of the test item is between below LoD (0.22 µg/LL (PBS) and 67.1 µg/L/ 64.2 µg/L (GST) at a loading of 0.1g/L after 2 and 24 hours.


 


The dissolution of Fe of the test item is in a range of below LoD (1.78 µg/L)/ below LoQ (5.95 µg/L,GMB) and 16.5 µg/L/ 25.4 µg/L (GST) at a loading of 0.1g/L after 2 and 24 hours.


 


A pH dependent dissolution can be observed.In conclusion, since the dissolved Zr and Fe concentrations were below 65 µg/L even at the highest loading of 0.1g/L, referring to a solubility of 0.065 %, this pigment may reasonably be considered biologically inert.


 


Bacteria reverse mutation assay


The bacteria reverse mutation assay (Engelhardt_1992) yielded a negative result. However, tests on the mutagenic potential of zirconium zircon with encapsulated hematite in bacteria are considered dispensable for principal considerations, since inorganic metal compounds are frequently negative in this assay due to limited capacity for uptake of metal ions (Guidance on information requirements and chemical safety assessment, Chapter R.7a, p. 387; HERAG facts sheet mutagenicity, Chapter 2.1). The evaluation of this reference is therefore primarily based on the method description.

Justification for classification or non-classification

The chemical and physiological properties of the pigment zirconium zircon with encapsulated hematite 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.