Disodium dihydrogenpyrophosphate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Remarks:

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:

1971

Report date:

1971

Materials and methods

Test guideline

Test guideline 1

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

yes

Remarks:

Animals were examined at 24 and 72 hours only. No data reported on reversibility of effects. Study uses intact and abraded skin. No controls were included in the study.

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion)

Deviations:

yes

Remarks:

Animals were examined at 24 and 72 hours only. No data reported on reversibility of effects. Study uses intact and abraded skin. No controls were included in the study.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Disodium dihydrogenpyrophosphate

EC Number:

231-835-0

EC Name:

Disodium dihydrogenpyrophosphate

Cas Number:

7758-16-9

Molecular formula:

H4O7P2.2Na

IUPAC Name:

Sodium acid pyrophosphate

Constituent 2

Reference substance name:

sodium acid pyrophosphate

IUPAC Name:

sodium acid pyrophosphate

Details on test material:

- Name of test material : Sodium acid pyrophosphate
- Analytical purity: No data

Test animals

Species:

rabbit

Strain:

not specified

Details on test animals or test system and environmental conditions:

No data

Test system

Type of coverage:

not specified

Preparation of test site:

other: Shaved, abraded and intact

Vehicle:

unchanged (no vehicle)

Controls:

not specified

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied : 0.5 g


VEHICLE
Used as received.

Duration of treatment / exposure:

24 hours

Observation period:

Up to 72 hours

Number of animals:

6, 3 males and 3 females.

Details on study design:

TEST SITE
- Type of wrap if used: Rubber (occlusive)


REMOVAL OF TEST SUBSTANCE
No data


SCORING SYSTEM:
The Draize dermal method of testing primary irritant substance as described in the Code of Federal Refulations under the Federal Hazardous Substances Labelling Act, Part 191.11, Chapter 1, Title 21.

Compounds producing combined averages (primary irritation indexes) of 2 or less are only mildly irritating; indexes from 2 to 5 are moderate irritants and those with scores above 5 are considered severe or primary irritants.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0.5

Max. score:

4

Reversibility:

fully reversible within: 72 hours

Results 2

Irritation parameter:

erythema score

Basis:

other: remaining 5 animals tested

Time point:

24/48/72 h

Score:

0

Max. score:

4

Results 3

Irritation parameter:

edema score

Basis:

other: all animals tested

Time point:

24/48/72 h

Score:

0

Max. score:

4

Irritant / corrosive response data:

The primary dermal irritation index is calculated by the following:

Total ÷ 4 = Primary dermal irritation index

Other effects:

No data

Any other information on results incl. tables

Table 1: Results for Sodium acid pyrophosphate

Exposure time Hours	Rabbit No.							Mean
		8M	15M	16M	32F	33F	34F
		Score	Score	Score	Score	Score	Score
Erythema
24	Intact	1	0	0	0	0	0	0.17
72	Intact	0	0	0	0	0	0	0.00
24	Abraded	4	4	4	2	4	2	3.33
72	Abraded	4	4	4	0	0	0	2.00
Subtotal								5.50
Oedema
24	Intact	0	0	0	0	0	0	0.00
72	Intact	0	0	0	0	0	0	0.00
24	Abraded	4	4	4	1	3	1	2.83
72	Abraded	4	4	4	0	0	0	2.00
Subtotal								4.83
Total score								10.33
(Total/4) Primary Irritation Index								2.58
Result							Mild Irritant

 

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Sodium acid pyrophosphate was determined to be a mild irritant to rabbit skin with a primary dermal irritation score of 2.58, mostly the reactions were noted in abraded skin.
This study is selected as the key study because the results are sufficient in order to derive a reliable conclusion on classification and labelling. The substance is not considered to be classified in accordance with Regulation (EC) No. 1272/2008 (EU CLP) as only mild effects are noted in 1 animal at the 24 hour time period and therefore due to the mild nature of the reaction and considering it was only observed in one animal for the parameter erythema the absence of 48 hr scores is not considered to have a detrimental effect on the reliability of the study for use in classification and labelling.