Silicic acid, aluminum salt

Endpoint summary

Description of key information

Skin:
Not irritating to the skin (RA calcined Kaolin)
Eye:
Causes serious eye damage

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

Except for in vitro studies on the skin and eye irritating potential of silicic acid, aluminium salt, there are no in vivo data for the substance itself. Therefore a read-across approach was conducted from the structurally related substance kaolin, calcined.

Skin irritation

The skin irritation potential of silicic acid, aluminium salt was determined by Paulus (2010) according to OECD guideline (Draft proposal for a new guideline. In vitro skin irritation: human skin model test, Dezember, 2007) (Paulus, 2010, RL2). Approx. 25 mg of the test item were applied to EpiDerm^TM tissues. After 35 min incubation tissues were rinsed and incubated for further 42 hours. The cell viability was measured photometrically by dehydrogenase conversion of MTT into a blue formazan salt. No decrease of cell viability was detected compared to the negative control. Under these test conditions the substance has no skin irritation potential.

 

0.5 gram of the read across substance kaolin, calcined, as 50% (w/w) mixture in distilled water was applied to the skin of New Zealand rabbits (Engelhard Corp., 1997, RL2). The study was performed according to OECD guideline 404 under GLP-conditions. The observation period was terminated at 72 hours instead of 14 days, as no signs for dermal irritation (edema or erythema, respectively) were noted at any reading time point.

 

Eye irritation

The eye irritancy potential of silicic acid, aluminium salt was screened by using the Hen's Egg Test - Chorioallantoic Membrane (HET-CAM) assay (Paulus and Andres, 2010, RL1). 0.3 mL of the powdery test item was added to the membrane of 6 nine day incubated Lohmann Leghorn chicken eggs for 300 seconds. The calculated mean irritation score was in the first experiment 9.45 and in the second experiment 9.86 for the test material. As well, in a second, confirming study (Paulus and Andres, 2010, RL1)

the calculated mean irritation score for silicic acid, aluminium salt of batch no. 3080270 was 9.78. These values correspond to a classification as severely irritant. In this case, HET-CAM assay according to ICCVAM Test Method Evaluation Report: Appendix G -> ICCVAM recommended HET-CAM Method Protocol (Nov 2006) resulting in risk of serious eye damage, the substance is not to be tested in vivo.

Effects on eye irritation: corrosive

Justification for classification or non-classification

Based on in vitro studies no skin irritating effects, but severe eye irritating effects are expected from the exposure to silicic acid, aluminium salt. The negative result for the skin irritating potential in vitro is supported by an in vivo study of a structurally related compound. There is no need for further testing for eye irritation in vivo.

Skin

There is conclusive data available which is not sufficient for classification.

Eye

DSD: Silicic acid, aluminium salt is classified as Xi, R41: Risk of serious eye damage.

CLP: Silicic acid, aluminium salt causes serious eye damage, Category 1, H318.