[No public or meaningful name is available]

Endpoint summary

Description of key information

In conclusion, since the dissolved Cr, Fe, Ti and Zn and concentrations from this pigment under simulated physiological conditions were below 20.9 µg/L, 90.2 µg/L, 94.6 µg/L and 112 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.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

The chemical and physiological properties of the pigment Chromium, iron, titanium and zinc spinel and rutile 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 Cr from the pigment Chromium, iron, titanium and zinc spinel and rutile in physiological media was in a range of below 2.98 and 10.3 µg/L (GST) after 2 hours. After 24 hours a dissolution range from below 3.43 – 20.9 µg/L (GST) was measured.

Solubility of Fe from the pigment Chromium, iron, titanium and zinc spinel and rutile in physiological media was in a range of below LOD and 25.2 µg/L (GST) after 2 hours. After 24 hours a dissolution range from below LOD – 90.2 µg/L (GST) was measured.

Solubility of Ti from the pigment Chromium, iron, titanium and zinc spinel and rutile in physiological media was in a range of below LOD and 25.7 µg/L (GST) after 2 hours. After 24 hours a dissolution range from below 0.83 – 94.6 µg/L (GST) was determined.

Solubility of Zn from the pigment Chromium, iron, titanium and zinc spinel and rutile in physiological media was in a range of below 0.688 and 86.9 µg/L (GST) after 2 hours. After 24 hours a dissolution range from below LOD – 112 µg/L (GST) was determined.

In conclusion, since the dissolved Cr, Fe, Ti and Zn and concentrations from this pigment under simulated physiological conditions were below 20.9 µg/L, 90.2 µg/L, 94.6 µg/L and 112 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.