Silicic acid, aluminum magnesium salt

Endpoint summary

Description of key information

Under the experimental conditions, various forms of synthetic amorphous silica showed no irritating effects to the skin and to the eyes of albino rabbits. However, it must be taken into account that silicic acid, aluminium magnesium salt (MAS) could produce mechanical irritation to the skin and the eyes. Depending on the production parameters applied in the precipitation and filtration process, a wide range of MAS products with different chemical properties can be produced (see chapter 2.1). Particularly, the variable content of sodium ions and variable pH values (up to pH 10.6) of SMAS products have to be considered. Due to their chemical properties, MAS products might cause irritating effects to the skin and the eyes. This potential hazard is addressed by the advice to wear suitable personal protective equipment, including goggles, gloves and protective clothing.

Additional information

Only secondary literature is available on Silicic acid, aluminium magnesium salt (MAS) for skin and eye irritation. The original studies are not available and documentation of the reviewed data is limited. Therefore data of MAS are insufficient for assessment. However, there are data for structurally related compounds.

Skin irritation

Various forms of synthetic amorphous silica were not irritating to intact skin of albino rabbits exposed to 0.5 g of the respective test item for 24 hours under occlusive conditions. Not even evidence of erythema or edema was observed following topical application of the test materials within 72 hours (Keating 1973). Dermal application of 20 mg Syloid 244 per skin area of rabbits for 24 hours under occlusive conditions showed no irritating effects.

The skin irritation potential of silicic acid, titanium salt was determined according to the national guideline 16CFR 1500.11 by Borgstedt (1982). The test item was applied as an aqueous slurry (0.5 mL of 1 g test material in 1 mL water) to the intact skin of rabbits for 24 hours under occlusive conditions. Under the conditions of the test, the test substance was not irritating to the skin.

Silicic acid, aluminium magnesium salt (MAS) was a weak primary skin irritant in rabbits and had no cumulative skin irritation in guinea pigs (CTFA 1970, Munch 1944, Hazelton Laboratories, Inc. 1968). No gross effects were observed in any of these studies. The application of 2 g of MAS made to the skin of two human subjects daily for one week caused no effects (Munch 1944). Based on the limited documentation of the reviewed studies, the available data of MAS are insufficient for assessment and only data of the structurally related compounds were taken into account for risk assessment.

Eye irritation

Sodium silicoaluminate was used as fine powder (0.1 g) and has shown slight, reversible irritating effects on the conjunctivae of the rabbit eyes (Calkins 1978f). Iris or cornea were not affected at all. Based on the results, the test item is not ocular irritating.

According to the OECD guideline 405, the eye irritation potential of Syloid C 803 was determined by instillation of the test material into the conjunctival sac of rabbits (Bücher 2002). None of the rabbits showed swelling of lids or any redness of conjunctivae. No changes of iris or the cornea could be observed in the animals.

Using the Draize test, a 4 % solution of Silicic acid, aluminium magnesium salt (MAS) caused minimal eye irritating effects in rabbits (CTFA 1970 and Hazelton Laboratories, Inc. 1968). Based on the limited documentation of the reviewed studies, the available data of MAS are insufficient for assessment and only data of the structurally related compounds were taken into account for risk assessment.

Skin irritation

Various forms of synthetic amorphous silica were not irritating to intact skin of albino rabbits exposed to 0.5 g of the respective test item for 24 hours under occlusive conditions. Not even evidence of erythema or edema was observed following topical application of the test materials within 72 hours (Keating 1973). Dermal application of 20 mg Syloid 244 per skin area of rabbits for 24 hours under occlusive conditions showed no irritating effects.

The skin irritation potential of silicic acid, titanium salt was determined according to the national guideline 16CFR 1500.11 by Borgstedt (1982). The test item was applied as an aqueous slurry (0.5 mL of 1 g test material in 1 mL water) to the intact skin of rabbits for 24 hours under occlusive conditions. Under the conditions of the test, the test substance was not irritating to the skin.

 

Eye irritation

Sodium silicoaluminate was used as fine powder (0.1 g) and has shown slight, reversible irritating effects on the conjunctivae of the rabbit eyes (Calkins 1978f). Iris or cornea were not affected at all. Based on the results, the test item is not ocular irritating.

According to the OECD guideline 405, the eye irritation potential of Syloid C 803 was determined by instillation of the test material into the conjunctival sac of rabbits (Bücher 2002). None of the rabbits showed swelling of lids or any redness of conjunctivae. No changes of iris or the cornea could be observed in the animals.

 

Effect level: empty Endpoint conclusion: Adverse effect observed

Effect level: empty Endpoint conclusion: Adverse effect observed

Effect level: empty Endpoint conclusion: Adverse effect observed

Justification for classification or non-classification

Based on the studies of structurally related compounds, no irritating effects are expected from the exposure to silicic acid, aluminium magnesium salt. No need for classification as skin or eye irritant.

However, depending on the variable composition of MAS, the potential to cause irritating effects to the eyes and the skin have to be considered and precautions are required to protect the eyes and the skin.