Tetrapotassium pyrophosphate

Endpoint summary

Description of key information

Skin irritation: Four in vivo studies are available for skin irritation. The study reported by Freeman (1988) as the key study is conducted according to modern guidelines and performed in a GLP accredited facility. The results of this study are sufficient for classification and labelling in accordance with Regulation (EC) No. 1272/2008 (EU CLP) and as such tetrapotassium pyrophosphate is not classified for skin irritation. The additional studies ( Birch MD, 1973, Parke GSE, 1975 and Younger FM, 1961) are provided to support this conclusion. 
Eye irritation: Five in vivo studies are available for eye irritation. The key study (Freeman C, 1988) is conducted to a protocol similar to modern day guidelines and was performed in a GLP accredited facility. Despite only having assessed the eyes of two animals, the results are deemed sufficient for classification and labelling in accordance with Regulation (EC) No. 1272/2008 (EU CLP) and confirm that tetrapotassium pyrophosphate should be classified as irritating to eyes (Category 2). The supporting data (Kamienski, 1971, Younger FM, 1961, Parke GSE, 1975 and Birch MD, 1973) are in agreement with this conclusion on classification and labelling.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

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:

13/06/1988 to 17/06/1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

yes

Remarks:

, please see additional information on methods.

GLP compliance:

yes

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 on May 18, 1988
- Age at study initiation: Young
- Weight at study initiation: 2.3 - 2.69 kg
- Housing: individually housed in stainless steel cages. DAGB cageboard bedding was used in the litter pans.
- Diet (e.g. ad libitum): ad libitum; Purina High Fiber Rabbit Chow 5326
- Water (e.g. ad libitum): ad libitum; fresh tap water
- Acclimation period: no data


ENVIRONMENTAL CONDITIONS
- Temperature (°F): 67 - 73°F
- Humidity (%): 60 - 64 %
- Photoperiod (hrs dark / hrs light): 12 hour fluorescent light: 12 hour dark cycle.


IN-LIFE DATES: May 18, 1988 - 13/06/1988

Type of coverage:

occlusive

Preparation of test site:

shaved

Vehicle:

other: the test material was moistened with physiological saline

Controls:

not specified

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 gram

VEHICLE
no vehicle was used.

Duration of treatment / exposure:

4 h

Observation period:

72 h

Number of animals:

3

Details on study design:

TEST SITE
- Area of exposure: 2"x2"
- % coverage: no data
- Type of wrap if used: The test site was covered with an eight-ply, 2"x2" gauze pad which was secured with hypoallergenic tape. The entire trunk of the animal was wrapped in a semi-occlusive cheesecloth bandage. Elizabethan collars were also fitted to prevent disturbance of the test site.
- Other: Once unwrapped the test site was allowed to "rest" for 30 minutes to allow for regression of pressure and hydration effects.
- There were two test sites per animal, either side of the spinal chord served as a separate site.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): The test site was wiped clean with methanol then rinsed with tap water.
- Time after start of exposure:Four hours after application

SCORING SYSTEM: Draize, Woodard and Calvery. J. Pharm. Exp. Ther., 83, 384 (1944)

Irritation parameter:

erythema score

Basis:

other: all animals tested

Time point:

24/48/72 h

Score:

0

Max. score:

4

Irritation parameter:

edema score

Basis:

other: all animals tested

Time point:

24/48/72 h

Score:

0

Max. score:

4

Irritant / corrosive response data:

See Table 1.

Other effects:

All animals remained healthy throughout the study.

Table 1 - Individual skin scores at 4.5 hours, 0.5 hours after the wrapping was removed.

Animal / sex	Left			Right
	ER	ED	other	ER	ED	other
1 / male	1	0	0	1	0	0
2 / female	0	0	0	0	0	0
3 / male	0	0	0	0	0	0
Irritation score = 0.3/ 8.0

ER - erythema/ eschar

ED - edema

other - other comments

Zero scores were observed at all subsequent time points, i.e. 24h, 48h, and 72h.

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of this study and based on the Primary Irritation Index, the test material is 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. Tetrapotassium pyrophosphate 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).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye 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:

11/08/1986 - 25/08/1986

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Hazleton Research Animals, Inc., Denver, Pennsylvania on July 16th, 1986
- Age at study initiation: The animals were young.
- Weight at study initiation: 2.53-2.67 kg
- Housing: Individual stainless steel cages, DAGB cageboard bedding was used in litter pans.
- Diet (e.g. ad libitum): Purina High Fiber Rabbit Chow 5326, ad libitum
- Water (e.g. ad libitum): fresh tap water ad libitum
- Acclimation period: July 16th 1986 - August 7th 1986


ENVIRONMENTAL CONDITIONS
- Temperature (°F): 68 - 75 °F
- Humidity (%): 50 - 64 %
- Photoperiod (hrs dark / hrs light): 12 hours fluorescent light, 12 hours dark cycle.


IN-LIFE DATES: From: 16/07/1986 To: 25/08/1986

Vehicle:

unchanged (no vehicle)

Controls:

other: yes, the untreated left eyes served as controls.

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.10 gram

Duration of treatment / exposure:

washed eyes: exposure was 20-30 seconds before the eye were rinsed.
not washed: The test material was not removed by any external processes.

Observation period (in vivo):

13 days

Number of animals or in vitro replicates:

4

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): 2 of the 4 animals had their eye washed, the remaining 2 did not.
- Time after start of exposure: 20-30 seconds after treatment.
- The washed eyes were rinsed with 100 mL of tap water for 1 minute.

SCORING SYSTEM: Eyes were assessed for irritation using the method of Draize.


TOOL USED TO ASSESS SCORE: The eyes were examined with the aid of 2% fluorescein dye. Test eyes which retained fluorescein at 24 hours were examined with dye at subsequent assessment times until corneal irritation was no longer observed or dye was no longer retained.

Irritation parameter:

cornea opacity score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0.6

Max. score:

4

Reversibility:

fully reversible within: 13 days

Remarks on result:

other: unwashed eyes

Irritation parameter:

iris score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

2

Remarks on result:

other: unwashed eyes

Irritation parameter:

conjunctivae score

Remarks:

redness

Basis:

animal #1

Time point:

24/48/72 h

Score:

3

Max. score:

3

Reversibility:

fully reversible within: 13 days

Remarks on result:

other: unwashed eyes

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

24/48/72 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 13 days

Remarks on result:

other: unwashed eyes

Irritation parameter:

cornea opacity score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

other: Unwashed eyes

Irritation parameter:

iris score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

2

Remarks on result:

other: unwashed eyes

Irritation parameter:

conjunctivae score

Remarks:

redness

Basis:

animal #2

Time point:

24/48/72 h

Score:

0.3

Max. score:

3

Reversibility:

fully reversible within: 13 days

Remarks on result:

other: unwashed eyes

Irritation parameter:

chemosis score

Basis:

animal #2

Time point:

24/48/72 h

Score:

3

Max. score:

4

Reversibility:

fully reversible within: 13 days

Remarks on result:

other: unwashed eyes

Irritant / corrosive response data:

Several hours after instillation, severe hemorrhagic conjunctivitis was noted in both unwashed eyes, one of which also had iritis; washed eyes had moderate conjunctivitis. Within 24 hours, hemorrhagic conjunctivitis was present in all eyes and slight corneal opacities were evident in both unwashed eyes. Irritation gradually resolved, and by day 4 both of the washed eyes had recovered; unwashed eyes had mild conjunctival redness and discharge. By day 13, both of the unwashed eyes had recovered and the test was terminated.

Washing the eyes with tap water shortly after exposure decreased both the severity and the duration of the irritation observed.

Other effects:

All animals remained healthy during study.

Table 1 - Eye scores per animal

Animal	Time point	Cornea opacity / area	Iris iritis	Conjunctiva			Cornea stain / area	Other
				redness	chemosis	discharge
#1 Male Unwashed eye	1 h	0/0	0	3	2	3	-	Ch*
	24 h	1/1	0	3	3	3	+/1	Ch
	48 h	1/1	0	3	2	3	+/1	Ch
	72 h	0/0	0	3	1	3	0/0	Ch
	Day 4	0/0	0	2	0	2	-	Ch
	Day 7	0/0	0	1	0	1	-	Ch
	Day 10	0/0	0	0	0	1	-	0
	Day 13	0/0	0	0	0	0	-	0
#2 Male Unwashed eye	1 h	0/0	1	3	2	3	-	Ch
	24 h	1/1	0	3	1	3	+/1	Ch
	48 h	0/0	0	2	0	3	0/0	Ch
	72 h	0/0	0	2	0	3	-	Ch
	Day 4	0/0	0	2	0	3	-	Ch
	Day 7	0/0	0	0	0	1	-	0
	Day 10	0/0	0	0	0	1	-	0
	Day 13	0/0	0	0	0	0	-	0
#3 Male washed eye	1 h	0/0	0	0	2	3	-	0
	24 h	0/0	0	1	0	1	0/0	Ch
	48 h	0/0	0	1	0	0	-	Ch
	72 h	0/0	0	0	0	0	-	0
	Day 4	0/0	0	0	0	0	-	0
	Day 7	0/0	0	0	0	0	-	0
	Day 10	0/0	0	0	0	0	-	0
	Day 13	0/0	0	0	0	0	-	0
#4 Male washed eye	1 h	0/0	0	0	2	3	-	0
	24 h	0/0	0	1	1	2	0/0	Ch
	48 h	0/0	0	1	0	0	-	Ch
	72 h	0/0	0	1	0	0	-	0
	Day 4	0/0	0	1	0	0	-	0
	Day 7	0/0	0	1	0	0	-	0
	Day 10	0/0	0	1	0	0	-	0
	Day 13	0/0	0	1	0	0	-	0

* Ch - hemorrhagic conjunctiva

Table 2 - Primary eye irritation indexes

Scoring intervals	Unwashed	Washed
1h	18.5	10.0
24 h	21.0	6.0
48 h	15.5	2.0
72 h	12.0	1.0
Day 4	9.0	0
Day 7	3.0	0
Day 10	2.0	0
Day 13	0	0

Interpretation of results:

Category 2 (irritating to eyes) based on GHS criteria

Conclusions:

Under the conditions of this study, the author states that the test material is temporarily approximated to be moderately irritating to unwashed eyes and mildly irritating to washed eyes.

Study is conducted according to the appropriate guidelines (EU AND US) and under the conditions of GLP. This study is considered to be acceptable and to adequately satisfy both the guideline requirement and the regulatory requirement for this endpoint.
In addition this study is considered to be acceptable for classification under Regulation (EC) No. 1272/2008 (EU CLP) as Irritating to eyes (Category 2) as 2 animals exhibited a positive response of conjunctival oedema (chemosis) of ≥2 calculated as a mean score following grading at 24, 48 and 72 hours.
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 effects noted and is therefore submitted as a key study with supporting data also provided to support the conclusions on classification and labelling.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Justification for classification or non-classification

Skin irritation: Tetrapotassium pyrophosphate is not considered to be irritating to skin in accordance with Regulation (EC) No. 1272/2008 (EU CLP). The key study is considered to be adequate and reliable for the purposes of classification and therefore further in vivo testing is not considered to be scientifically justified.

Eye irritation: Tetrapotassium pyrophosphate is considered to be classified as irritating to the eyes (category 2) in accordance with Regulation (EC) No. 1272/2008 as the key study shows that the following criteria for classification are met:

Two animals exhibited the following responses (Based on the mean scores at 24, 48 and 72 hours);

- Chemosis ≥ 2

All effects were fully reversible and therefore tetrapotassium pyrophosphate is classified as category 2 (Reversible effects on the eye) in accordance with Regulation (EC) No.1272/2008 (EU CLP). No further testing is deemed scientifically justified.

There are no data (study or workplace) to support a classification for respiratory irritation.