Phosphonic acid

Endpoint summary

Description of key information

Skin irritation/corrosion study in rabbits showed that phosphonic acid (80% aqueous solution) is corrosive to skin

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 1977

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP study, and no OECD Guideline followed. Acceptable basic data.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: U.N. Transport Regulations; U.S. Federal Regulations

Deviations:

not specified

GLP compliance:

no

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Bantin and Kingman Ltd.
- Age at study initiation: no data
- Weight at study initiation: 2-3 kg
- Housing: one animal per cage
- Diet: standard rabbit diet
- Water: ad libitum
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS: no data

IN-LIFE DATES: no data

Type of coverage:

occlusive

Preparation of test site:

shaved

Vehicle:

not specified

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 ml
- Concentration (if solution): 80%

Duration of treatment / exposure:

4 hours

Observation period:

3 minutes, 1, 4, 24, and 48 hours

Number of animals:

3 males and 3 females

Details on study design:

TEST SITE
- Area of exposure: back
- % coverage: 1 inch square
- Type of wrap if used: the patch was covered with an overlapping patch of impermeable plastic adhesive tape. After the final application, the entire trunk was bound with Sleek occlusive tape.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): gently cleansed with water
- Time after start of exposure: 4 hours

SCORING SYSTEM: FDA scoring system, simlar to Draize scoring system

Irritation parameter:

edema score

Basis:

animal: #1,3 and 5

Time point:

24 h

Score:

> 4

Max. score:

4

Reversibility:

not reversible

Remarks on result:

not determinable

Remarks:

Complete breakdown of skin with bleeding - rabbit sacrificed

Irritation parameter:

erythema score

Basis:

animal: #1,3 and 5

Time point:

24 h

Score:

> 4

Max. score:

4

Reversibility:

not reversible

Remarks on result:

not determinable

Remarks:

Complete breakdown of skin with bleeding -rabbit sacrificed

Irritation parameter:

edema score

Basis:

animal: #2,4 and 6

Time point:

24 h

Score:

3

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

edema score

Basis:

animal: #2, 4 and 6

Time point:

24 h

Score:

> 4

Max. score:

4

Reversibility:

not reversible

Remarks on result:

not determinable

Remarks:

Dark red brown area

Irritation parameter:

primary dermal irritation index (PDII)

Basis:

animal: All

Time point:

other: 48/72h

Reversibility:

not reversible

Remarks on result:

not determinable

Remarks:

Substance corrosive, all animals were sacrificed

Irritant / corrosive response data:

At the 1 h reading visible necrosis of the skin was only evident in 2 of the 6 sites treated with this material. However at the 4 h reading all sites treated with phosphorous acid (80%) showed visible necrosis. Visible necrosis was evident at all treated
sites after contact of more than 3 and up to 60 minutes. It was impossible to calculate the primary irritation scores for the materials since for humane reasons the rabbits were sacrificed before the required 72 h reading could be taken.

	Oedema mean score  (6 rabbits)	Erythema/Eschar mean score (6 rabbits)
3 minutes	0	0.25
1 hour	0.83	2 rabbits visible necrosis
4 hours	2	all 6 rabbits dark red brown area
24 hours	3 rabbits dark red brown, and 3 rabbits complete breakdown of skin with bleeding; 4 rabbits sacrificed
48 hours	2 rabbis left: blackened skin, but minimal breakdown

Interpretation of results:

other: Cat.1A Corrosive

Remarks:

based on CLP 67/548/EEC and 1272/2008.

Conclusions:

Phosporous acid (80%) caused visible necrosis at 2 sites after contact for 3-60 minutes in 2 of the 6 sites. The remaining 4 sites showed necrosis after contact of more than 1 hour and up to 4 hours. Based on these results and according to EU criteria Phosporous acid (80%) was considered to be corrosive and the material needs to be classified as Cat.1A Corrosive according to the classification criteria outlined in 67/548/EEC and 1272/2008.

Executive summary:

A skin corrosion study was conducted, according to U.N. Transport Regulations and U.S. Federal Regulations on 3 male and 3 female New Zealand White rabbits using the test material Phosporous acid (80%). 0.5 ml of the test material was applied under occlusion to the shaved backs of the 6 rabbits. Patch application was repeated after 3 minutes and 1 hour. The test material was not applied at further treatments after 4 hours. Observations for dermal irritation or defects were made at 3 minutes, and 1, 4, 24, and 48 hours after application of the test material. Phosporous acid (80%) caused visible necrosis at 2 sites after contact for 3-60 minutes in 2 of the 6 sites. The remaining 4 sites showed necrosis after contact of more than 1 hour and up to 4 hours. It was impossible to calculate the primary irritation score, since for humane reasons the rabbits were sacrificed before the required 72 hours reading could be taken. Based on these results and according to EU criteria Phosporous acid (80%) was considered to be corrosive and the material needs to be classified as corrosive according to the classification criteria outlined in 67/548/EEC and 1272/2008.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

In a skin irritation study, which was performed in accordance with U.N. Transport Regulations and U.S. Federal Regulations, 3 male and 3 female New Zealand White rabbits were exposed to phosphonic acid (80%). Visible necrosis was observed at 2 sites after contact for 3-60 minutes in 2 of the 6 sites. The remaining 4 sites showed necrosis after contact of more than 1 hour and up to 4 hours. Based on these results and according to EU criteria phosphonic acid (80%) was considered to be corrosive to the skin and the material needs to be classified as a Cat.1B Corrosive to skin and eyes according to the classification criteria outlined in 67/548/EEC and 1272/2008.

As phosphonic acid was considered to be corrosive to the skin, an eye irritation study is waived based on column 2 of REACH Annex VIII.

Justification for selection of skin irritation / corrosion endpoint:
One study was available which was performed similar to the OECD Guidelines

Justification for selection of eye irritation endpoint:
Studies on eye irritation were waived because phosphonic acid was classified corrosive to skin

Effects on skin irritation/corrosion: corrosive

Effects on eye irritation: corrosive

Justification for classification or non-classification

The pH of Phosphonic acid is below 1 in a 1% aqueous solution. (see section 7.5.1: combined 28-day repeated dose toxicity study with the reproduction/developmental toxicity screening test of phosphonic acid (phosphorous acid) in rats by oral gavage).

Based on the available information, phosphonic acid should be classified as corrosive for the skin and eyes Category 1A, in accordance with the criteria outlined in Annex VI of 67/548/EEC and Annex I of 1272/2002/EC.