Dipotassium hydrogenorthophosphate

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:

1987

Report date:

1987

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: no data

Deviations:

not applicable

Principles of method if other than guideline:

Dipotassium phosphate at dosage levels of 300 and 20 mg/kg was in contact with the skin for 24 h under an occlusive wrap. Observations were conducted at approximately 3 h on the day of dosing and daily thereafter for 14 days.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Dipotassium hydrogenorthophosphate

EC Number:

231-834-5

EC Name:

Dipotassium hydrogenorthophosphate

Cas Number:

7758-11-4

Molecular formula:

H3O4P.2K

IUPAC Name:

dipotassium hydrogen phosphate

Details on test material:

- Name of test material: dipotassium phosphate
- Molecular formula: K2HPO4
- Substance type: solid
- Physical state: white granules
- Purity test date: > 99 % based on H2O content
- Lot/batch No.: 275B30202
- Other: FMC# 426

Test animals

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hazleton Researach Animals, Inc., Denver, Pennsylvania.
- Age at study initiation: young adult
- Weight at study initiation: 2.10 to 2.65 kg
- Housing: individually housed in stainless steel rabbit cages with DACB cageboard bedding used in litter pans.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 68 - 77 ºF
- Humidity (%): 28 - 44 %
- Photoperiod (hrs dark / hrs light): 12 h fluorescent light and 12 h dark

Test system

Type of coverage:

occlusive

Preparation of test site:

other: clipped

Vehicle:

physiological saline

Controls:

not specified

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 300 mg/kg and 20 mg/kg

Duration of treatment / exposure:

24 h

Observation period:

14 days

Number of animals:

5 animals

Details on study design:

TEST SITE
- Area of exposure: the trunk from the scapular to the pelvic floor.
- Type of wrap if used: 8 ply 4 x 4 inch gauze pad held in place with hypoallergenic tape. The test site was occluded with impervious plastic sheeting.


REMOVAL OF TEST SUBSTANCE
- Washing: the test site was wiped with clean gauze moistened with methanol, then rinsed with tap water.
- Time after start of exposure: approximately 24 h after application.


SCORING SYSTEM: Draize

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

4

Results 2

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

4

Results 3

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

24/48/72 h

Score:

1

Max. score:

4

Reversibility:

fully reversible within: 72 hrs

Results 4

Irritation parameter:

erythema score

Basis:

animal #4

Time point:

24/48/72 h

Score:

0.6

Max. score:

4

Reversibility:

fully reversible within: 72 hrs

Results 5

Irritation parameter:

erythema score

Basis:

animal #5

Time point:

24/48/72 h

Score:

0.3

Max. score:

4

Reversibility:

fully reversible within: 72 hrs

Results 6

Irritation parameter:

edema score

Basis:

other: all animals tested

Time point:

24/48/72 h

Score:

0

Max. score:

4

Irritant / corrosive response data:

Slight erythema was noted on the test sites of three rabbits in the 300 mg/kg group. All irritation resolved by day 4.

Other effects:

There were no treatment-related deaths, clinical signs, changes in body weight or treatment-related observations at necropsy.

Any other information on results incl. tables

Individual scores (300 mg/kg bw)

Animal #	ER	ED	O
24 hr
B5917M	0	0	0
B5918M	0	0	0
B5851M	1	0	0
B5905M	1	0	0
B5888M	1	0	0
Irritation score: 0.6/8.0
48 hr
B5917M	0	0	0
B5918M	0	0	0
B5851M	1	0	0
B5905M	1	0	0
B5888M	0	0	0
Irritation score: 0.4/8.0
72 hr
B5917M	0	0	0
B5918M	0	0	0
B5851M	1	0	0
B5905M	0	0	0
B5888M	0	0	0
Irritation score: 0.2/8.0
Day 4
B5917M	0	0	0
B5918M	0	0	0
B5851M	0	0	0
B5905M	0	0	0
B5888M	0	0	0
Irritation score: 0.0/8.0

Primary skin irritation scores for each group:

Scoring interval	Dosage level
	300 mg/kg	20 mg/kg
24 h	0.6 / 8.0	0 / 8.0
48 h	0.4 / 8.0	0 / 8.0
72 h	0.2 / 8.0	0 / 8.0
Day 4	0 / 8.0	0 / 8.0
Day 7	0 / 8.0	0 / 8.0
Day 14	0 / 8.0	0 / 8.0
Primary irritation Index	0.4 / 8.0	0.8 / 8.0

Mean body weights ± SD

Dosage level (mg/kg)	Body weights ± SD (kg)
	Day
	0	7	14
300	2.26 ± 0.223	2.31 ± 0.179	2.38 ± 0.169
20	2.23 ± 0.094	2.19 ± 0.218	2.15 ± 0.063

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of the study the authors concludes that the test material is temporarily approximated to be minimally irritating (300 mg/kg) and non-irritating (20.0 mg/kg).
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 in accordance with Regulation EC (No.) 1272/2008 (EU CLP). Dipotassium hydrogenorthophosphate is not considered to be classified according to Regulation (EC) No. 1272/2008 (EU CLP).