Synthetic amorphous magnesium silicate, with molar ratio (SiO2:MgO) range of 1.4-4

Eye irritation

Administrative data

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17-20 September 2009

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

The study has been performed using a sample from Dallas Group of America. The particle size analysis performed on the Dallas and PQ corporation material show that they are sufficiently similar. The only difference between the materials are the molar ratios. The molar ratio of the tested Dallas material is within the range of the PQ Corporation registered substance. No additional testing is therefore required.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Silicic acid, magnesium salt

EC Number:

215-681-1

EC Name:

Silicic acid, magnesium salt

Cas Number:

1343-88-0

Molecular formula:

MgO.xSiO2, the molar ratio SiO2:MgO typically ranges from 1.4-4

IUPAC Name:

Synthetic amorphous magnesium silicate, with molar ratio (SiO2:MgO) range of 1.4-4

Details on test material:

Synthetic magnesium silicate, SRR-000-57-6 , a white powder.
No further details given in study report.

Specific details on test material used for the study:

Synthetic magnesium silicate, SRR-000-57-6 , a white powder.
No further details given in study report.

Test animals / tissue source

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Kuiper Rabbitry, Gary, Indiana.
- Age at study initiation:10-12 weeks old
- Weight at study initiation: 2.44 to 2.63 kg
- Housing: House individually in stainless steel cages
- Diet: Purina Rabbit Chow available ad libitum
- Water (e.g. ad libitum): Water was available ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°F): 63-73
- Humidity (%):30-70

Test system

Vehicle:

unchanged (no vehicle)

Controls:

other: the contralateral eye served as the untreated control for each rabbit

Amount / concentration applied:

The animals were dosed by instilling 0.1 mL packed volume of the test material into one eye of each animal.

Duration of treatment / exposure:

72 hours

Observation period (in vivo):

The eyes were examined at 1, 24, 48 and 72 hours after treatment for signs of irritation.

Number of animals or in vitro replicates:

Three animals were dosed.

Details on study design:

Three animals were dosed by instilling 0.1 mL packed volume of the test material into one eye of each animal and then holding the eye lids together for one second to prevent loss of the material. The eyes were examined at 1, 24, 48 and 72 hours after treatment and a eye irritation score given according to Draize. If there were no evidence of irritation the study was ended at 72 hours. All test animals were sacrificed at the end of the study.

Results and discussion

In vivo

Results

Irritation parameter:

maximum mean total score (MMTS)

Basis:

mean

Score:

6.67

Max. score:

110

Reversibility:

fully reversible within: 48-72 hours

Remarks on result:

other: No corneal or iridial reactions were observed for any rabbit, conjunctival reactions did not exceed a grading of 1 at any point

Irritant / corrosive response data:

There was minimal eye irritation reactions in all of the test subjects and the maximum group mean score was 6.67/110.0 at the 1 hour observation.
No corneal or iridial responses were evident in any rabbit. The mean 24-72 h score for conjunctival redness response was 0.44 and for chemosis was 0. Neither reaction exceeded EU classification criteria.

Other effects:

No further effects to report.

Any other information on results incl. tables

Rabbit Number	Tissue	1	24	48	72
918	Cornea (D-A)	-	0	0	0
	Iris	0	0	0	0
	Conjunctiva (R-S-D)	6	2	0	0
	Total	6	2	0	0
919	Cornea (D-A)	-	0	0	0
	Iris	0	0	0	0
	Conjunctiva (R-S-D)	6	2	0	0
	Total	6	2	0	0
920	Cornea (D-A)	-	0	0	0
	Iris	0	0	0	0
	Conjunctiva (R-S-D)	8	4	2	0
	Total	8	4	2	0
Averages	Cornea (D-A)	-	0	0	0
	Iris	0	0	0	0
	Conjunctiva (R-S-D)	6.67	2.67	0.67	0
	Total	6.67	2.67	0.67	0

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

There were minimal eye irritation reactions in all of the test subjects and the maximum group score was 6.67/110.0 at the 1 hour observation. In accordance with the OPPTS/OECD Guidelines, the sample was classified as Toxicity category III (Corneal irritation clearing in 7 days or less).

The mean 24-72 h score for conjunctival redness response was 0.44 and for chemosis was 0. Neither reaction exceeded EU classification criteria.

Executive summary:

A Dallas sample of magnesium silicate was tested for eye irritation in accordance with the OECD guidelines 405. The grade of magnesium silicate was not noted in the report but the particle size distribution and molar ratio which differs with grades will not alter the outcome of an irriation study. The study concluded that minimal eye irritation was observed. In accordance with the OPPTS/OECD Guidelines, the sample was classified as Toxicity category III (Corneal irritation clearing in 7 days or less).