Calcium bis(dihydrogenorthophosphate)

Endpoint summary

Description of key information

Skin irritation (similar to OECD 404, RL2): not irritating 
Eye irritation (OECD 405, RL1): irreversible effects on the eye

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:

20/8/1984 to 7/11/1984

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPPTS 870.2500 (Acute Dermal Irritation)

Deviations:

yes

Remarks:

Reactions at abraded skin sites were also observed, observations were not recorded at 48 hr

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

yes

Remarks:

occlusive dressing, also abraded skin tested, 48 hour reading is mising

Principles of method if other than guideline:

Study states protocols were consitent with or exceeded the requirements of EPA and OECD guidelines at the time of the study.

GLP compliance:

not specified

Species:

rabbit

Strain:

other: Stauffland albino

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Phillips Rabbitry, Soquel, California
- Weight at study initiation: 1.642 - 2.146 kg

Type of coverage:

occlusive

Preparation of test site:

other: abraded and non-abraded (shaved) sites

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount applied: 0.5 g

Duration of treatment / exposure:

4 hours

Observation period:

4 hours, 24 hours and 72 hours

Number of animals:

6

Details on study design:

TEST SITE
- Area of exposure: 1 inch²
- % coverage: no data
- Type of wrap if used: rubber damming


SCORING SYSTEM: Draize, 1965

Irritation parameter:

erythema score

Basis:

mean

Remarks:

6 animals

Time point:

other: 24/72h

Score:

0

Max. score:

4

Reversibility:

other: not applicable

Remarks on result:

no indication of irritation

Irritation parameter:

edema score

Basis:

mean

Remarks:

6 animals

Time point:

other: 24/72h

Score:

0

Max. score:

4

Reversibility:

other: not applicable

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

No irritation was observed either in intact or abraded skin.

Other effects:

Not applicable

 

Table 1: Results of a primary skin irritation study

 

Rabbit No	Skin	Erythema-eschar observation			Edema observation			Sum total	Score^*
		4 hr	24 hr	72 hr	4 hr	24 hr	72 hr
84-M-1084	Intact	0	0	0	0	0	0	0	0
	Abraded	0	0	0	0	0	0	0	0
84-M-1085	Intact	0	0	0	0	0	0	0	0
	Abraded	0	0	0	0	0	0	0	0
84-M-1086	Intact	0	0	0	0	0	0	0	0
	Abraded	0	0	0	0	0	0	0	0
84-M-1087	Intact	0	0	0	0	0	0	0	0
	Abraded	0	0	0	0	0	0	0	0
84-M-1088	Intact	0	0	0	0	0	0	0	0
	Abraded	0	0	0	0	0	0	0	0
84-M-1089	Intact	0	0	0	0	0	0	0	0
	Abraded	0	0	0	0	0	0	0	0

 

^*score = sum of individual values for each rabbit divided by six

Primary Irritant Score = 0

Interpretation of results:

GHS criteria not met

Conclusions:

Monocalcium phosphate was considered to be non-irritating. Calcium bis(dihydrogenorthophosphate) is not considered to be classified according to Regulation (EC) No. 1272/2008 (EU CLP).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was performed between 06 May 2010 and 02 June 2010.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method B.5 (Acute Toxicity: Eye Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

Principles of method if other than guideline:

Due to the low pH value of the test material a Rabbit Enucleated Eye Test (REET) was performed prior to the in vivo test. The results are given in Appendix 3 and indicated that the test material was unlikely to cause severe ocular irritancy.

GLP compliance:

yes (incl. QA statement)

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source:
Harlan UK Limited, Bicester, Oxon, UK

- Age at study initiation:
Twelve to twenty weeks old

- Weight at study initiation:
2.0 to 3.5 kg

- Housing:
The animals were individually housed in suspended cages. The animals were provided with environmental enrichment items which were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.

- Diet (e.g. ad libitum):
ad libitum (2030 Teklad Global Rabbit diet supplied by Harlan Teklad, Blackthorn, Bicester, Oxon, UK)

- Water (e.g. ad libitum):
ad libitum.

- Acclimation period:
At least five days


ENVIRONMENTAL CONDITIONS

- Temperature (°C):
17 to 23°C

- Humidity (%):
30 to 70%

- Air changes (per hr):
At least fifteen changes per hour

- Photoperiod (hrs dark / hrs light):
Twelve hours continuous light (06:00 to 18:00) and twelve hours darkness

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent no treatment

Amount / concentration applied:

TEST MATERIAL

- Amount(s) applied (volume or weight with unit):
A volume of 0.1 mL of the test material was placed into the conjunctival sac of the right eye, formed by gently pulling the lower lid away from the eyeball.

- Concentration (if solution):
Undiluted and used as supplied

Duration of treatment / exposure:

Test material was administered once on day 1. Observations continued until day 21. The test material was not removed from the eye of the test animal.

Observation period (in vivo):

Approximately 1 hour and 24, 48 and 72 hours following treatment. Additional observations were made on Days 7, 14 and 21 to assess the reversibility of the ocular effects.

Number of animals or in vitro replicates:

1 animal was tested in total. Due to the severity of the ocular responses produced in the first treated animal, and in accordance with UK Home Office guidelines, no additional animals were treated.

Details on study design:

REMOVAL OF TEST SUBSTANCE

- Washing (if done):
Not applicable

- Time after start of exposure:
Not applicable


SCORING SYSTEM:
Assessment of ocular damage/irritation was made approximately 1 hour and 24, 48 and 72 hours following treatment, according to the numerical evaluation given in Appendix 2, (from Draize J H (1977) "Dermal and Eye Toxicity Tests" In: Principles and Procedures for Evaluating the Toxicity of Household Substances, National Academy of Sciences, Washington DC p.48 to 49).


TOOL USED TO ASSESS SCORE:

Examination of the eye was facilitated by the use of the light source from a standard ophthalmoscope.

Irritation parameter:

cornea opacity score

Basis:

animal: 69201 Male

Time point:

24/48/72 h

Score:

1

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

iris score

Basis:

animal: 69201 Male

Time point:

24/48/72 h

Score:

1

Max. score:

2

Reversibility:

fully reversible within: 7 Days

Irritation parameter:

conjunctivae score

Basis:

animal: 69201 Male

Time point:

24/48/72 h

Score:

2

Max. score:

3

Reversibility:

not reversible

Remarks:

Haemorrhage scattered over the majority of the nictitating membrane Day 7 to Day 14, Off white appearance covering one quarter of the upper conjunctival membrane Day 7 to Day 21.

Irritation parameter:

chemosis score

Basis:

animal: 69201 Male

Time point:

24/48/72 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 14 days

Irritant / corrosive response data:

Ocular Reactions
Individual scores for ocular irritation are given in Table 1.
Scattered or diffuse corneal opacity was noted in the treated eye at the 24, 48 and 72 hour observations with translucent corneal opacity noted at the 7, 14 and 21 Day observations.
Iridial inflammation was noted in the treated eye one hour after treatment and at the 24, 48, 72 Hour observations.
Moderate conjunctival irritation was noted in the treated eye one hour after treatment and at the 24, 48, 72 Hour, 7 and 14 Day observations with minimal conjunctival irritation at the 21 Day observations.
Haemorrhage scattered over the majority of the nictitating membrane was noted in the treated eye at the 7 and 14 Day observations. Off white appearance covering one quarter of the upper conjunctival membrane was noted in the treated eye at the 7, 14 and 21 Day observations.
The persistence of reactions in the treated eye at the 21 Day observation was considered to be indicative of irreversible ocular damage.

Other effects:

The animal showed expected gain in bodyweight during the study.

Table1              IndividualScores and Individual Total Scores for Ocular Irritation

Rabbit Number and Sex	69201Male
	IPR= 2
Time After Treatment	1 Hour	24 Hours	48 Hours	72 Hours	7 Days	14 Days	21 Days
CORNEA
Degree of Opacity	0	1	1	1	2	2	2
Area of Cornea Involved	0	2	2	2	2	1	1
IRIS	1	1	1	1	0	0	0
CONJUNCTIVA
Redness	2	2	2	2	2HP	2HP	1P
Chemosis	2	2	2	2	1	1	0
Discharge	2	2	2	2	1	1	0

IPR=  Initial pain reaction

H =      Haemorrhage scattered over the majority of the nictitating membrane

P =      Off white appearance covering one quarter of the upper conjunctival membrane

Table2              Individual Bodyweights and Bodyweight Change

Rabbit Number and Sex	Individual Bodyweight (kg)		Bodyweight Change (kg)
	Day 0	Day 21
69201Male	2.39	2.79	0.40

Interpretation of results:

Category 1 (irreversible effects on the eye) based on GHS criteria

Conclusions:

The test material produced irreversible ocular damage and was considered to be CORROSIVE to the rabbit eye (based on one rabbit only). In accordance with the Guidance on the application of Regulation (EC) No. 1272/2008 (EU CLP) the test substance meets the criteria for classification as corrosive to the eyes and no further testing is required.

Executive summary:

Introduction. The study was performed to assess the irritancy potential of the test material to the eye of the New Zealand White rabbit. The method was designed to meet the requirements of the following:

OECD Guidelines for the Testing of Chemicals No. 405 "Acute Eye Irritation/Corrosion" (adopted 24 April 2002)

Method B5 Acute Toxicity (Eye Irritation) of Commission Regulation (EC) No. 440/2008

Initial considerations. Due to the low pH value of the test material a Rabbit Enucleated Eye Test (REET) was performed prior to the in vivo test. The results are given in Appendix 3 and indicated that the test material was unlikely to cause severe ocular irritancy.

Result. A single application of the test material to the non-irrigated eye of one rabbit produced translucent corneal opacity, iridial inflammation and moderate conjunctival irritation. Other ocular effects noted were off white appearance covering one quarter of the upper conjunctival membrane and haemorrhage scattered over the majority of the nictitating membrane. The persistence of reactions in the treated eye at the 21‑Day observation was considered to be indicative of irreversible ocular damage.

Conclusion. The test material produced irreversible ocular damage and was considered to be CORROSIVE to the rabbit eye (based on one rabbit only).

       

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin Irritation:

In order to evaluate the skin irritating potential of calcium bis(dihydrogenorthophosphate) one in vivo skin irritation study is available. The study performed in 1985 similar to OECD 404. This skin irritation test was performed with six male Stauffland albino rabbits. A 4-hour occlusive exposure to ca. 0.5 g of the unchanged test material produced no effects during the whole observation period on the treated sites of the animals. The mean score for the 24, 48 and 72 h reading for erythema and edema, respectively, was 0. Under the conditions of the study, the test substance is considered to be non-irritating to skin.

 

Eye Irritation:

Three eye irritation tests are available for calcium bis(dihydrogenorthophosphate). In vivo eye irritation tests were performed in 2010 and 1985. The study from 2010 served as key study since it was performed according to OECD Guideline 404. The in vivo test was initially performed with one male New Zealand white rabbit. A volume of 0.1 mL of the test material, which was found to weigh approximately 88 mg (as measured by gently compacting the required volume into an adapted syringe) was placed into the conjunctival sac of the right eye. After application the animal was observed 21 days. Evaluation of the animal resulted in mean scores for the 24, 48 and 72 hour reading for cornea opacity, iritis, conjunctivae redness and chemosis were 1.0, 1.0, 2.0 and 2.0, respectively. Conjunctivae redness and corneal opacity were not reversible until day 21 after treatment. Haemorrhage scattered over the majority of the nictitating membrane and off white appearance covering on quarter of the upper conjunctival membrane was observed until 14 or 21 days after treatment, respectively. These effects leading to the conclusion that calcium bis(dihydrogenorthophosphate) has an eye damaging potential and no further animal was tested.

This result is supported by another in vivo study performed in 1985 similar to OECD 405. Six female Stauffland albino rabbits were used to evaluate the irritating potential of calcium bis(dihydrogenorthophosphate). 100 mg of the test material was placed in one eye and the eyes were observed until day 24 after treatment. Evaluation the animals with unwashed eyes, the means scores for the 24, 48 and 72 hour reading for cornea opacity, iritis, conjunctivae redness and chemosis were 2.78, 1.61, 2.67 and 1.5, respectively. Conjunctivae redness and chemosis and corneal opacity were not reversible until day 24 after treatment. This results lead also to the conclusion that calcium bis(dihydrogenorthophosphate) has irreversible effects on the eyes.

 Before the in vivo test was done in 2010, an in vitro Rabbit Enucleated Eye test was performed due to the low pH value of the test material. This test was performed before guidelines for in vitro tests were available. As OECD guideline 492 is available since 2015 and the test was performed in 2010 a major deficiency is the too short incubation time of 10 minutes instead of 6 hours for solids. Furthermore, 30 mg instead of 50 mg were used for the test. The relative mean viability of the test material treated tissue was 76.6% after a 10-minute exposure which leads to the conclusion that the test material has no irritating potential. Due to the major deficiencies described above and a negative result this study was devalidated and not used for classification.

Conclusion

Taken together, the available data on irritation/corrosion with calcium bis(dihydrogenorthophosphate) (CAS 7758-23-8) do not indicate any hazardous potential on skin but shows eye damaging potential. Therefore, the test substance is not to be classified regarding skin irritation but has to be classified as Eye Dam. Category 1 (H318).

Justification for classification or non-classification

The available data on skin irritation with calcium bis(dihydrogenorthophosphate) do not meet the criteria for classification according to Regulation (EC) No. 1272/2008, and are therefore conclusive but not sufficient for classification.

The available data on eye irritation with calcium bis(dihydrogenorthophosphate) meet the criteria for classification according to Regulation (EC) No. 1272/2008, and are therefore classified as Eye Damage Category 1 (H318).

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