Magnesium hydroxide

Eye irritation

Administrative data

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2010-04-22 to 2010-09-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.5 (Acute Toxicity: Eye Irritation / Corrosion)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2400 (Acute Eye Irritation)

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: JMAFF guidelines (2000); including the most recent partial revisions.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Magnesium hydroxide

EC Number:

215-170-3

EC Name:

Magnesium hydroxide

Cas Number:

1309-42-8

Molecular formula:

H2MgO2

IUPAC Name:

magnesium dihydroxide

Specific details on test material used for the study:

- Name of the test material used in the report: Magnesium hydroxide
- Appearance: white powder
- Batch No.: 20BR0026
- Purity: 99.90%
- Storage: at room temperature in the dark
- Expiry date: 2012-01-31

Test animals / tissue source

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Harlan, Belton, Leics, England
- Age at study initiation: Animals used within the study were at least 6 weeks old
- Weight at study initiation: Body weights were at least 1.0 kg
- Housing: Animals were individually housed in labelled cages with perforated floors and shelters.
- Diet: Pelleted diet for rabbits approximately 100 grams per day was provided at least three times a week.
- Water: Free access to tap water
- Acclimation period: Acclimitisation period was at least 5 days before start of treatment under laboratory conditions.
Results of analysis for diet, hay and water were assessed and did not reveal any findings that were considered to have affected the study integrity.
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.0±3.0°C
- Humidity (%): 40-70%
- Air changes (per hr): 15 air changes per hour
- Photoperiod (hrs dark / hrs light):12 hours artificial fluorescent light and 12 hours darkness per day.

IN-LIFE DATES: From: 06-04-2010 to: 2-04-2010

Test system:

Amount/ concentration applied:
Animals were treated by instillation of on average, 57.3 mg (range 57.0-57.5 mg) of the test substance (a volume of approximately 0.1mL) in the conjunctival sac of one of the eyes.

Observation period:
Observations were made 1, 24, 48 and 72 hours after instillation.
Mortality/ Viability: Twice daily
Toxicity: At least once daily
Body weight: Day of treatment and after the final observation
Necropsy: No necropsy was performed according to protocol.
Irritation: The eyes of each animal were examined approximately 1, 24, 48 and 72 hours after instillation of the test substance. The irritation scores and a description of all other (local) effects were recorded.

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent no treatment

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 57.3 mg (range 57.0 – 57.5 mg)

Duration of treatment / exposure:

24 hours

Observation period (in vivo):

72 hours

Number of animals or in vitro replicates:

3 males were used in the treatment.

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done):
no


SCORING SYSTEM:
See box: Any other information on materials ane methods incl. tables.

TOOL USED TO ASSESS SCORE: 2% fluorescein; Where standard lighting was considered inadequate for observing minor effects, eye examinations were performed using an ophthalmic examination lamp.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Results 2

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

2

Remarks on result:

no indication of irritation

Results 3

Irritation parameter:

conjunctivae score

Remarks:

redness

Basis:

mean

Time point:

24/48/72 h

Score:

1

Max. score:

3

Reversibility:

fully reversible within: 72 hours

Results 4

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

0.2

Max. score:

4

Reversibility:

fully reversible within: 72 hours

Irritant / corrosive response data:

Instillation of approximately 57 mg of Magnesium hydroxide into one eye of each of three rabbits resulted in effects on the cornea, iris and conjunctivae. The corneal injury consisted of a slight dulling of the normal lusture and/or epithelial damage (maximum 10% of the corneal area) in two animals. The corneal injury had resolved within 24 or 48 hours. Iridial irritation grade 1 was observed in all animals and had resolved within 24 hours. The irritation of the conjunctivae consisted of redness, chemosis and discharge and completely resolved within 72 hours in all animals.

Coloration/ Remnants
Remnants of the test substance were present in the eye of two animals on Day 1.

Toxicity/ Mortality:
No symptoms of systemic toxicity were observed in the animals during the test period and no mortality occurred.

Any other information on results incl. tables

Table 1: Mean value eye irritation scores 

	Mean 24, 48 and 72 hours.
Animal	Corneal opacity	Iris	Conjunctivae
			Redness	Chemosis
328	0.0	0.0	1.0	0.0
377	0.0	0.0	1.0	0.3
379	0.0	0.0	1.0	0.3

 

 

Table 2: Animal specifications

Animal	Sex	Age at start (weeks)	Body weights( grams)
			Prior to application	At termination
328	Male	10-12	2198	2256
377	Male	7-9	1516	1701
379	Male	7-9	1615	1739

 

Table 3: Individual Eye Irritation Scores

		Cornea			Iris	Conjunctivae
Animal No.	Time after dosing (hours)	Opacity (0-4)	Area (0-4)	Fluor area (%)	(0-2)	Redness (0-3)	Chemosis (0-4)	Discharge (0-3)	Comments
1	1	0	0	-	1	1	1	1	-
	24	0	0	0	0	2	0	0	-
	48	0	0	-	0	1	0	0	-
	72	0	0	-	0	0	0	0	-
2	1	0	1	-	1	1	2	1	b g
	24	0	0	0	0	2	1	0	-
	48	0	0	-	0	1	0	0	-
	72	0	0	-	0	0	0	0	-
3	1	0	1	-	1	2	2	2	b g
	24	0	1	10	0	2	1	1	g
	48	0	0	-	0	1	0	0	-
	72	0	0	0	0	0	0	0	-

Fluor area: Green staining after fluorescein treatment (percentage of total corneal area)

b Remnants of the test substance in the eye.

g Slight dulling of the normal luster of the cornea.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Based on these results Magnesium hydroxide does not have to be classified and has no obligatory labelling requirement for eye irritation according to the GHS criteria.

Executive summary:

In a primary eye irritation study conducted according to OECD guideline 405, 57 mg of magnesium hydroxide was instilled into the conjunctival sac of one of the eyes of 3 male rabbits without rinsing. Observations were made 1, 24, 48 and 72 hours after instillation. Irritation was scored by the method of Draize.

 

Instillation of the test substance resulted in effects on the cornea, iris and conjunctivae. The corneal injury consisted of slight dulling of the normal lustre and/or epithelial damage (maximum 10% of the corneal area) in two animals. The corneal injury had resolved within 24 or 48 hours. Iridial irritation grade 1 was observed in all animals and had resolved within 24 hours. The irritation of the conjunctivae consisted of redness, chemosis and discharge and completely resolved within 72 hours in all animals.

 

In this study, magnesium hydroxide is not an eye irritant based on GHS criteria.