Iron titanium pseudobrookite

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

In conclusion, since the dissolved Fe, Ti and Al and concentrations from this pigment under simulated physiological conditions were below 178 µg/L, 106 µg/L and 139 µg/L (GST) , respectively even at the highest loading of 0.1g/L, corresponding to a solubility of less than 0.4 % after 24 hours, this pigment may reasonably be considered biologically inert.

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 Pseudobrookite 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.

 

Solubility of Fe from the pigment Pseudobrookite in physiological media was in a range of below LOD and 25.5 µg/L (GST) after 2 hours. After 24 hours a dissolution range from below LOD - 178 µg/L (GST) was measured.

 

Solubility of Ti from the pigment Pseudobrookite in physiological media was in a range of below LOD and 15.7 µg/L (GST) after 2 hours. After 24 hours a dissolution range from below LOD – 105.8 µg/L (GST) was measured.

 

Solubility of Al from the pigment Pseudobrookite in physiological media was in a range of below LOD and 57.9 µg/L (GST) after 2 hours. After 24 hours a dissolution range from below LOD – 138.4 µg/L (GST) was determined.

 

In conclusion, since the dissolved Fe, Ti and Al and concentrations from this pigment under simulated physiological conditions were below 178 µg/L, 106 µg/L and 139 µg/L (GST) , respectively even at the highest loading of 0.1g/L, corresponding to a solubility of less than 0.4 % 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 Pseudobrookite 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 negligible. In consequence, this substance may reasonably be considered inert in nearly all media relevant for uptake into the body and also the compartment relevant for distribute within body tissues.

 

Hence, no genetic toxicity/mutagenic 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.