Calcium nitrite

Endpoint summary

Description of key information

No in vitro skin or eye irritation studies are available or required.

 

In a guideline study, to GLP, calcium nitrite (hydrate) (0.5 mL) was applied (4-hr, semi-occluded) to the clipped skin of three male rabbits. Transient very slight irritation was reported in a single animal at the 1 hr observation point. No other irritation was reported (Parcell, 1997).

 

In a guideline study, to GLP, calcium nitrite (hydrate) (0.1 mL) produced severe irritation and corrosive effects following instillation into one eye of each of two rabbits (Parcell, 1996).

 

No relevant respiratory tract irritation data were identified.

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:

12-15 December 1995

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Good quality study, conducted to GLP. The test material was a 34% solution of hydrated calcium nitrite.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

29.12.92

Deviations:

no

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Froxfield (UK) Ltd., Petersfield, Hampshire, England
- Age at study initiation: 11-14 weeks
- Weight at study initiation: 2.4-3.2 kg
- Housing: house individually in metal cages with perforated floors
- Diet (e.g. ad libitum): SDS Stanrab (P) standard laboratory rabbit diet ad libitum
- Water (e.g. ad libitum): drinking water ad libitum
- Acclimation period: "all animals were acclimatised to the experimental environment", but no details on the acclimation period given

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19
- Humidity (%): 30-70
- Air changes (per hr): 19
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: No data

Type of coverage:

semiocclusive

Preparation of test site:

clipped

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 mL [equivalent to about 0.17 mL as calcium nitrite]
- Concentration (if solution): the test material was applied as supplied (34% aqueous solution of calcium nitrite)

Duration of treatment / exposure:

4 hours

Observation period:

72 hours after exposure

Number of animals:

Three males

Details on study design:

TEST SITE
- Area of exposure: 25 mm x 25 mm from the dorso-lumbar region of each rabbit
- % coverage: no data
- Type of wrap if used: The gauze pad was covered by an elastic adhesive dressing

REMOVAL OF TEST SUBSTANCE
- Washing (if done): warm water (30-40°C) (the treated area was subsequently blotted dry)
- Time after start of exposure: 4 hours (upon removal of dressing and gauze pad)

OBSERVATION TIME POINTS
(indicate if minutes, hours or days): On the day of treatment (approximately 60 minutes after removal of the dressings) and on the subsequent three days (equivalent to 24, 48 and 72 hours after exposure)

SCORING SYSTEM:
Local dermal irritation was assessed using the following system:
Erythema and eschar formation: No erythema (0); slight erythema (1); well-defined erythema (2); moderate to severe erythema (3); severe erythema (beet redness) to slight eschar formation (injuries in depth) preventing erythema reading (4).
Oedema formation: No oedema (0); very slight oedema (barely perceptible) (1); slight oedema (edges of area well-defined by definite raising) (2); moderate oedema (raised approximately 1 mm) (3); severe oedema (raised by more than 1 mm and extending beyond the exposure area) (4).

Irritation parameter:

erythema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: No evidence of erythema was seen at the 24, 48 and 72-hour time points.

Remarks on result:

no indication of irritation

Irritation parameter:

edema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: No evidence of oedema was seen at the 24, 48 and 72-hour time points.

Remarks on result:

no indication of irritation

Irritation parameter:

overall irritation score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

8

Reversibility:

other: No evidence of irritation was seen at the 24, 48 and 72-hour time points.

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

Transient very slight erythema was observed in one animal 60 minutes after removal of the dressing (no evidence of irritation was apparent at the subsequent observation time points). No dermal response was seen in the remaining two animals.

Other effects:

- Other adverse local effects: no data
- Other adverse systemic effects: No signs of ill health or toxicity were reported.

Interpretation of results:

GHS criteria not met

Conclusions:

In a guideline study, to GLP, calcium nitrite (hydrate) (0.5 mL) was applied (4-hr, semi-occluded) to the clipped skin of three male rabbits. Transient very slight irritation was reported in a single animal at the 1 hr observation point. No other irritation was reported.

Executive summary:

In an EU Method B.4 study, the skin irritant potential of calcium nitrite (hydrate) was assessed in three male New Zealand White rabbits. The test material (DCI) was available as a 34% aqueous solution of calcium nitrite. A 0.5 mL semi-occlusive application of the test material was made to the clipped skin for 4 hours. Following removal of the dressing, the treated sites were washed and subsequently assessed for evidence of erythema (and eschar) formation and oedema formation after approximately 1 hour, and again 24, 48 and 72 hours later.

 

One rabbit displayed transient very slight erythema one hour after removal of the dressing, though no evidence of irritation was apparent at the subsequent observation time points. No dermal response was seen in the remaining two animals. The overall irritation score was 0 (out of 8). No clinical signs of toxicity were reported.

 

Based on the results of this study, no classification for skin irritation is required under EU CLP criteria (EC 1272/2008).

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:

18 December 1995 - 6 January 1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Good quality study, conducted to GLP. The test material was a 34% solution of hydrated calcium nitrite.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

29.12.92

Deviations:

no

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Froxfield (UK) Ltd., Petersfield, Hampshire, England
- Age at study initiation: 12-13 weeks
- Weight at study initiation: 2.7-3.1 kg
- Housing: Individually housed in metal cages with perforated floors
- Diet (e.g. ad libitum): SDS Stanrab (P) standard laboratory rabbit diet ad libitum
- Water (e.g. ad libitum): drinking water ad libitum
- Acclimation period: not specified

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19
- Humidity (%): 30-70
- Air changes (per hr): 19
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: No data

Vehicle:

unchanged (no vehicle)

Controls:

other: contralateral eye of treated animals served as concurrent control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 mL [equivalent to about 0.034 mL as calcium nitrite]
- Concentration (if solution): the test material was administered as supplied (34% aqueous solution of calcium nitrite)

Duration of treatment / exposure:

Eyelids were gently held together for one second before releasing; no subsequent washing to remove test substance.

Observation period (in vivo):

17 days. Examination of the eyes was made 1 hour and 1, 2, 3 (24, 48 and 72 hours), 4, 7, 14, 15 and 17 days after instillation.

Number of animals or in vitro replicates:

Two (one female, sex not specified in the other)

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): the treated eye was not rinsed
- Time after start of exposure: not applicable

SCORING SYSTEM: Ocular irritation was assessed using the prescribed numerical system:
Corneal opacity: No ulceration or opacity (0); scattered or diffuse areas of opacity (other than slight dulling of normal lustre), details of iris clearly visible (1); easily discernable translucent areas, details of iris slightly obscured (2); nacreous areas, no details of iris visible, size of pupil barely discernible (3); opaque cornea, iris not discernible through the opacity (4).
Iris: normal (0); markedly deepened rugae, congestion, swelling, moderate circumcorneal hyperaemia or injection (or combinations thereof), iris still reacting to light (sluggish reaction is positive) (1); no reaction to light, haemorrhage or gross destruction (or combinations thereof) (2).
Conjunctivae: blood vessels normal (0); some blood vessels hyperaemic (injected) (1); diffuse, crimson colour, individual vessels not easily discernible (2); diffuse beefy red (3).
Chemosis: no swelling (0); any swelling above normal (includes nictating membranes) (1); obvious swelling with partial eversion of lids (2); swelling with lids about half-closed (3); swelling with lids more than half-closed (4).

Any other lesion not covered by this scoring system was described.


TOOL USED TO ASSESS SCORE: handheld light

Irritation parameter:

overall irritation score

Reversibility:

other: reversibility was not fully assessed due to humane sacrifice of the animals on Day 15 and 17 (after instillation of the test substance), respectively

Remarks on result:

other: An irritation index could not be determined because of the corrosive effects

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: Corneal effects were only apparent 2 weeks after instillation of the test material; reversibility was not fully assessed due to humane sacrifice of the animals on Day 15 and 17 (after instillation of the test substance), respectively

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

2

Reversibility:

other: Iridial effects were only apparent 2 weeks after instillation of the test material; reversibility was not fully assessed due to humane sacrifice of the animals on Day 15 and 17 (after instillation of the test substance), respectively

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Score:

2.3

Max. score:

3

Reversibility:

other: Conjunctival effects (redness) tended to worsen with time; reversibility was not fully assessed due to humane sacrifice of the animals on Day 15 and 17 (after instillation of the test substance), respectively

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

2

Max. score:

4

Reversibility:

other: Conjunctival effects (chemosis) tended to worsen with time; reversibility was not fully assessed due to humane sacrifice of the animals on Day 15 and 17 (after instillation of the test substance), respectively

Irritant / corrosive response data:

Conjunctival redness and chemosis scores of 2-3 were observed in the first animal at all time points (scores of 1-3 were observed in the second animal throughout the observation period); in both cases the effects tended to worsen with time. Necrosis of the conjunctiva and nictating membrane was reported for both animals. Corneal and iridial effects were only apparent 2 weeks after instillation of the test material; these also worsened with time (during the third week of the observation period). Due to the severity of the effects the animals were killed on Day 15 and 17, respectively.

Other effects:

- Lesions and clinical observations: No signs of ill health or toxicity were reported.
- Ophthalmoscopic findings: no data
- Histopathological findings: no data
- Effects of rinsing or washing: not applicable

Interpretation of results:

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

Conclusions:

In a guideline study, to GLP, calcium nitrite (hydrate) (0.1 mL) produced severe irritation and corrosive effects following instillation into one eye of each of two rabbits.

Executive summary:

In an EU Method B.5 study, to GLP, the ocular irritant potential of calcium nitrite (hydrate) was assessed in two New Zealand White rabbits. The test material (DCI) was available as a 34% aqueous solution of calcium nitrite. Initially, a 0.1 mL instillation of the test material was made to the eye of one female and both lids were gently closed for one second before releasing. The other eye remained untreated and acted as the control. Due to the severity of the observed effects only one other animal (sex unspecified) was treated.

 

Following instillation of the test material, conjunctival redness and chemosis were seen in both animals within one hour. In both cases, the effects tended to worsen as the study progressed, leading to the sacrifice of the animals on Day 15 and 17, respectively. Additional effects included necrosis of the conjunctiva and nictating membrane, along with corneal and iridial effects (only apparent 2 weeks after instillation) which also worsened with time. An irritation index could not be determined because of the corrosive effects. No clinical signs of toxicity were reported.

 

As the results were based on only two rabbits, it is not possible to give a definitive interpretation according to EU CLP criteria (EC 1272/2008). However, it is considered appropriate to classify the test material for serious eye damage (Category 1), as the severe effects observed tended to worsen with time and are not expected to be reversible.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

No relevant human irritation/corrosion data were identified.

 

In an EU Method B.4 study, the skin irritant potential of calcium nitrite (hydrate) was assessed in three male New Zealand White rabbits. The test material (DCI) was available as a 34% aqueous solution of calcium nitrite. A 0.5 mL semi-occlusive application of the test material was made to the clipped skin for 4 hours. Following removal of the dressing, the treated sites were washed and subsequently assessed for evidence of erythema (and eschar) formation and oedema formation after approximately 1 hour, and again 24, 48 and 72 hours later. One rabbit displayed transient very slight erythema one hour after removal of the dressing, though no evidence of irritation was apparent at the subsequent observation time points. No dermal response was seen in the remaining two animals. The overall irritation score was 0 (out of 8). No clinical signs of toxicity were reported (Parcell, 1997).

 

In an EU Method B.5 study, to GLP, the ocular irritant potential of calcium nitrite (hydrate) was assessed in two New Zealand White rabbits. The test material (DCI) was available as a 34% aqueous solution of calcium nitrite. Initially, a 0.1 mL instillation of the test material was made to the eye of one female and both lids were gently closed for one second before releasing. The other eye remained untreated and acted as the control. Due to the severity of the observed effects only one other animal (sex unspecified) was treated. Following instillation of the test material, conjunctival redness and chemosis were seen in both animals within one hour. In both cases, the effects tended to worsen as the study progressed, leading to the sacrifice of the animals on Day 15 and 17, respectively. Additional effects included necrosis of the conjunctiva and nictitating membrane, along with corneal and iridial effects (only apparent 2 weeks after instillation) which also worsened with time. An irritation index could not be determined because of the corrosive effects. No clinical signs of toxicity were reported (Parcell, 1996).

 

Based on the available information, OECD experts considered that sodium nitrite is a moderate eye irritant, but is non-irritant to skin in rabbits (OECD, 2005).

 

No respiratory tract irritation data were identified. A new study was not conducted as it is not a REACH Standard Information Requirement.

Justification for classification or non-classification

Based on the results of the available in vivo skin irritation study (Parcell, 1997), calcium nitrite does not require classification as a skin irritant according to EU CLP criteria (EC 1272/2008).

 

As the results were based on only two rabbits in the available in vivo eye irritation study (Parcell, 1996), it is not possible to give a definitive interpretation according to EU CLP criteria (EC 1272/2008). However, it is considered prudent to classify calcium nitrite for serious eye damage (Category 1), as the severe effects observed tended to worsen with time and are not expected to be reversible.