Sodium dihydrogenorthophosphate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation / corrosion, other

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:

No data

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:

1990

Report date:

1990

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

no

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

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

- Name of test material: monosodium phosphate
- Reference No. B485AB002
- Storage: room temperature
- FMC-T#: 860
- Physical description: white powder

Test animals

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hazleton Research Animals, Inc., Denver, Pennsylvania
- Age at study initiation: Young adult
- Weight at study initiation: 2.25 - 2.67 kg
- Housing: Individually housed in stainless steel cages with DACB cageboard bedding was used in the litter pans.
- Diet: Provided
- Water: Provided

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 68 - 72 ºF
- Humidity (%): 51 - 66 %
- Photoperiod (hrs dark / hrs light): 12 h dark / 12 h light

Test system

Type of coverage:

semiocclusive

Preparation of test site:

shaved

Vehicle:

physiological saline

Controls:

no

Amount / concentration applied:

0.5 g of test material.

Duration of treatment / exposure:

4 h

Observation period:

72 h

Number of animals:

Three

Details on study design:

TEST SITE
Area of exposure: From the scapular to the pelvic region. One test site was located on each side of the spinal column.
Type of wrap if used: Test material was weighed onto each 8-ply, 2 x 2 inch gauze pad and moistened with physiological saline. The gauze pad was secured to each test site with hypoallergenic tape. The entire trunk of the animal was wrapped with a semi-occlusive cheesecloth bandage.
The rabbits were dosed approximately 4 h after initiation of the light cycle.

REMOVAL OF TEST SUBSTANCE
Washing: Wrapping and pads were removed and the test sites were wiped with clean gauze moistened with methanol, then rinsed with tap water.
Time after start of exposure: 4 h.

SCORING SYSTEM: Approximately 30 min after unwrapping, the test sites of each rabbit were scored for irritation using the method of Draize. The 30 minute delay was instituted to allow for regression of pressure and hydration effects. The site was evaluated daily thereafter.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

erythema score

Basis:

other: all animals tested

Time point:

other: mean 24, 48 and 72 hours

Score:

0

Max. score:

4

Reversibility:

other: Not applicable

Results 2

Irritation parameter:

edema score

Basis:

other: all animals testing

Time point:

other: mean 24, 48 and 72 hours

Score:

0

Max. score:

4

Reversibility:

other: not applicable

Irritant / corrosive response data:

No irritation was noted on any of the test sites during any of the scoring intervals, and the test was terminated following the 72-h scoring.

Other effects:

All animals remained healthy throughout the study.

Any other information on results incl. tables

Table 3. Individual irritation scores

Animal #	Left		Right
	Erythema/eschar	Edema	Erythema/eschar	Edema
	4.5 hours:
B7879F	0	0	0	0
B7847M	0	0	0	0
B7877F	0	0	0	0
	24 hours:
B7879F	0	0	0	0
B7847M	0	0	0	0
B7877F	0	0	0	0
	48 hours:
B7879F	0	0	0	0
B7847M	0	0	0	0
B7877F	0	0	0	0
	72 hours:
B7879F	0	0	0	0
B7847M	0	0	0	0
B7877F	0	0	0	0

Table 4. The group irritation scores for each scoring interval are presented below:

Scoring Interval	Irritation Score
4.5 h	0
24 h	0
48 h	0
72 h	0
Primary Irritation Index
0 / 8.0

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of this study and based on the FMC rating system, the test material is temporarily approximated by the author to be non-irritating to intact skin when applied topically to New Zealand White rabbits.
This study has been selected as the key study because the results are sufficient in order to derive a reliable conclusion on classification and labelling. Sodium dihydrogenorthophosphate is not considered to be classified according to Regulation (EC) No. 1272/2008 (EU CLP) as no effects were noted for the relevant parameters (erythema/eschar or oedema).