Sodium dihydrogenorthophosphate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vivo

Remarks:

In vivo. Study was performed prior to the update of the REACH Regulation and prior to the validation of in vitro test methods.

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1986-07-15 to 1986-07-19

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1987

Report date:

1987

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: No guideline followed

Principles of method if other than guideline:

Monosodium Phosphate (MSP) Technical was instilled into the test eyes of four New Zealand White rabbits at a dose of 0.1 g. The eyes of two rabbits remained unwashed while the eyes of the remaining two rabbits were gently washed with 100 mL of tap water approximately 20 - 30 seconds after treatment. Eyes were assessed for irritation using the method of Draize at 1, 24, 48 and 72 h after instillation.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Sodium dihydrogenorthophosphate

EC Number:

231-449-2

EC Name:

Sodium dihydrogenorthophosphate

Cas Number:

7558-80-7

Molecular formula:

H3O4P.Na

IUPAC Name:

sodium dihydrogen phosphate

Details on test material:

Identity: Monosodium phosphate (MSP)
Formulation: Technical
Reference number: 485B2097U
Storage: room temperature
Purity: > 99 % based on water content
Stability: stable indefinitely
Chemical composition: NaH2PO4
FMC-T#: 429
Physical description: white granules

Test animals / tissue source

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Hazleton Research Animals, Inc., Denver, Pennsylvania, USA.
- Age at study initiation: Young adult
- Weight at study initiation: 2.63 to 2.97 kg
- Housing: Individual housing in stainless steel rabbit cages. DACB cageboard bedding was used in the litter pans.
- Diet: Ad libitum
- Water: Ad libitum
- Sex of animals: Male


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 69 - 74ºF
- Humidity (%): 52 - 58 %
- Photoperiod: 12 h dark / 12 h light


IN-LIFE DATES: From: 15-07-1986 To: 19-7-1986

Test system

Vehicle:

unchanged (no vehicle)

Controls:

other: The right eye of each rabbit was treated; and the remaining left eye was used as a control.

Amount / concentration applied:

TEST MATERIAL
- Amount applied: 0.1 g

Duration of treatment / exposure:

2 rabbits were exposed for approximately 30 seconds after treatment.
2 rabbits remined unwashed and therefore exposed for 72 h.

Observation period (in vivo):

72 h

Number of animals or in vitro replicates:

4 animals

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing: The eyes of two rabbits remained unwashed. The remaining two rabbits were gently washed with 100 mL of tap water at a rate of 100 mL per minute.
- Time after start of exposure: approximately 20 - 30 seconds after treatment.


SCORING SYSTEM: Draize. The primary irritation index was calculated separately for both washed and unwashed eyes for each scoring interval. Additional assessment of irritation provided by FMC Internal guidelines.


TOOL USED TO ASSESS SCORE: 2 % sodium fluorescein

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

conjunctivae score

Remarks:

redness

Basis:

other: all animals tested

Time point:

24/48/72 h

Score:

0.6

Max. score:

3

Reversibility:

fully reversible within: 72 hours

Results 2

Irritation parameter:

cornea opacity score

Basis:

other: all animals tested

Time point:

24/48/72 h

Score:

0

Max. score:

4

Results 3

Irritation parameter:

iris score

Basis:

other: all animals tested

Time point:

24/48/72 h

Score:

0

Max. score:

2

Results 4

Irritation parameter:

chemosis score

Basis:

other: all animals tested

Time point:

24/48/72 h

Score:

0

Max. score:

4

Irritant / corrosive response data:

One-hour after instillation, all eyes exhibited mild conjunctivitis. At the 24-h scoring, one of the washed had slight conjunctival redness; both unwashed eyes had slight conjuncitvitis. Washed eyes recovered within 48 h and unwashed eyes recovered within 72 h of dosing. Washing the eyes with tap water shortly after exposure slightly decreased both the severity and the duration of the irritation observed.

Other effects:

None reported

Any other information on results incl. tables

Table 1. Pretest eye examination:

Animal No.	Exam method	Right eye	Left eye	Body weight
B5431M	Penlight	N	N	2.63
	Fluorescein	N	N
B5436M	Penlight	N	N	2.97
	Fluorescein	N	N
B5430M	Penlight	N	N	2.97
	Fluorescein	N	N
B5432M	Penlight	N	N	2.70
	Fluorescein	N	N
Mean				2.82
± S.D.				± 0.178

Table 2. Individual eye scores: 1 hour

Animal Number	Cornea	Iris	Conjunctivae			Other comments
	Opacity/Area	Iritis	Redness	Chemosis	Discharge
B5431M	0 / 0	0	1	1	3	0
B5436M	0 / 0	0	1	1	3	0
B5430M (w)	0 / 0	0	0	1	3	0
B5432M (w)	0 / 0	0	1	0	3	0

Primary Eye Irritation Index = Unwashed 10.0/110, washed 8.0/110

(w) = washed

Table 3. Individual eye scores: 24 hour

Animal Number	Cornea	Iris	Conjunctivae			Cornea
	Opacity/Area	Iritis	Redness	Chemosis	Discharge	Stain / Area
B5431M	0 / 0	0	1	0	1	0 / 0
B5436M	0 / 0	0	1	0	2	0 / 0
B5430M (w)	0 / 0	0	0	0	0	0 / 0
B5432M (w)	0 / 0	0	1	0	0	0 / 0

Primary Eye Irritation Index = Unwashed 5.0/110, washed 1.0/110

(w) = washed

Individual eye scores: 48 hour

Animal Number	Cornea	Iris	Conjunctivae
	Opacity/Area	Iritis	Redness	Chemosis	Discharge
B5431M	0 / 0	0	1	0	0
B5436M	0 / 0	0	1	0	2
B5430M (w)	0 / 0	0	0	0	0
B5432M (w)	0 / 0	0	0	0	0

Primary Eye Irritation Index = Unwashed 4.0/110, washed 0/110

(w) = washed

Table 4. Individual eye scores: 72 hour

Animal Number	Cornea	Iris	Conjunctivae
	Opacity/Area	Iritis	Redness	Chemosis	Discharge
B5431M	0 / 0	0	0	0	0
B5436M	0 / 0	0	0	0	0
B5430M (w)	0 / 0	0	0	0	0
B5432M (w)	0 / 0	0	0	0	0

Primary Eye Irritation Index = Unwashed 0/110, washed 0/110

(w) = washed

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of this study, the author concludes that the test material is temporarily approximated to be minimally irritating to unwashed eyes and practically non-irritating to washed eyes.
Although the study has only been conducted on two animals (unwashed eyes) it is considered to be sufficient for classification and labelling due to the minimal effects noted and is therefore submitted as a key study with supporting data also provided to support the conclusions on classification and labelling.