Calcium nitrite

Endpoint summary

Description of key information

In a guideline study, to GLP, the acute oral LD50 of calcium nitrite was determined to be 283 mg/kg bw in rats (Olson, 1985).

 

No relevant acute dermal or inhalation toxicity data were identified for calcium nitrite.

 

According to OECD (2005) and ECB (2000) reviews, briefly describing the findings of an unpublished GLP acute inhalation study, there was no mortality or other toxicologically significant adverse effects in rats (10/sex/group) during a 14-day observation period following a 4-hr exposure to up to 100 mg/m3 of sodium nitrite (McLean-Head and Mould, 1985). As such, a 4-hr LC50 of >100 mg/m3 can be concluded for sodium nitrite.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

7 February - 7 March 1985

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

Good quality study, conducted to GLP. The discrepancy in acclimation period is not expected to influence the validity of the results. No details given on vehicle.

Qualifier:

according to guideline

Guideline:

other: US EPA TSCA Test rules (40 CFR Part 772.112-121 Subpart C)

Version / remarks:

26 July 1979

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

yes

Remarks:

Acclimation period of 3 days was used (guideline recommends at least 5 days)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories (Wilmington, MA)
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: 8-12 weeks
- Weight at study initiation: 200-400 g
- Fasting period before study: Night prior to dosing
- Housing: Individually in suspended, stainless steel wire mesh cages
- Diet (e.g. ad libitum): Commercial rodent ration (Agway Prolab 3000) ad libitum
- Water (e.g. ad libitum): Municipal tap water ad libitum
- Acclimation period: 3 days [current OECD guideline recommends 5 days]

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 72 ± 3°F (20.6-22.9°C)
- Humidity (%): 50 ± 15%
- Air changes (per hr): 10-13
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: no data

Route of administration:

oral: gavage

Vehicle:

other: not specified, presumably water

Details on oral exposure:

VEHICLE
- Concentration in vehicle: no data
- Amount of vehicle (if gavage): up to 0.86 mL (females) or 1.53 mL (males) (20 mL/kg)
- Justification for choice of vehicle: no data

Doses:

Main test: 100, 200, 300 or 400 mg/kg bw
[Preliminary test: 100, 300, 600, 900 or 1200 mg/kg bw]

No. of animals per sex per dose:

5
[3 males/group in preliminary test]

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: daily (clinical observations and mortality only)
- Necropsy of survivors performed: yes
- Other examinations performed: no

Statistics:

Calculation of the LD50, probit slope, and 95% confidence limit (CL) for the LD50 were achieved using an Applie II Plus Computer with a programme by Tallarida RJ and Murray RB (1981).

Preliminary study:

Mortalities were 0, 2, 2, 3 and 3 at respective doses of 100, 300, 600, 900 and 1200 mg/kg bw

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

283 mg/kg bw

Based on:

test mat.

95% CL:

>= 233 - <= 343

Mortality:

In the main test there was no mortality at the lowest tested dose (100 mg/kg bw), while all animals died at the highest tested dose (400 mg/kg bw). A single animal of each sex died at 200 mg/kg bw; 1 male and 4 females died at 300 mg/kg bw.

Clinical signs:

other: At 300 mg/kg bw, bluish cyanotic ears and feet as well as abnormally slow respiration were observed in three males, two of which also showed tremors and convulsions; such effects were also seen in a single female.

Gross pathology:

Necropsy of those animals displaying treatment-related mortality revealed moderate haemorrhaging in the stomach and small intestine. Other observations included a very pale integument, subcutis and liver, along with dusky leaden lungs which contained very little blood when sectioned. Mortailty was attributed to asphyxiation.

No significant lesions were observed in surviving animals.

Other findings:

- Organ weights: no data
- Histopathology: no data
- Potential target organs: no data

Interpretation of results:

Category 3 based on GHS criteria

Conclusions:

In a guideline study, to GLP, the acute oral LD50 of calcium nitrite was determined to be 283 mg/kg bw in rats.

Executive summary:

The acute oral toxicity of calcium nitrite (anhydrous powder) was investigated in Sprague-Dawley rats, in a US EPA TSCA guideline study (essentially equivalent to OECD Test Guideline 401), conducted according to GLP. Animals (5/sex/group) were administered the test substance (dissolved in an unspecified vehicle, presumably water) by oral gavage at doses of 100, 200, 300 or 400 mg/kg bw, and observed for up to 14 days. The dose range used in the main test was informed by a preliminary test involving gavage administration at levels of 100, 300, 600, 900 or 1200 mg/kg bw to male rats (3/group).

 

All animals died at the top dose (400 mg/kg bw) in the main test, while there were 2 and 5 deaths at the intermediate doses (200 and 300 mg/kg bw respectively). Deaths occurred within hours of test material administration and were attributed to asphyxiation. No mortality was observed in the low dose group (100 mg/kg bw). In the animals that died, clinical signs of toxicity were limited to discolouration of the ears/feet, tremors and reduced respiration in certain animals in the 300 mg/kg bw dose group. Upon necropsy, toxic effects included moderate haemorrhaging of the stomach and small intestine as well as effects on the skin, liver and lungs. No significant lesions were observed in surviving animals.

 

The acute oral LD50 was determined (using probit analysis) to be 283 mg/kg bw in rats (95% CL 233-343 mg/kg bw). Based on the results of this study, the test material should be classified for acute oral toxicity (category 3) according to EU CLP criteria (EC 1272/2008).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

283 mg/kg bw

Quality of whole database:

Overall, good-quality database which meets REACH Standard Information Requirements.

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Remarks:

Read-across from study conducted on a closely-related surrogate, sodium nitrite

Adequacy of study:

supporting study

Study period:

Not specified

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Remarks:

OECD SIDS (2005) describe as "critical study for SIDS endpoint", but with a reliability score of 4 ("not assignable") as it could not be evaluated by OECD assessors. Study evidently to GLP.

Justification for type of information:

Sodium nitrite is closely related to calcium nitrite, and is considered a suitable surrogate for read-across for this endpoint. See section 13 in IUCLID for full read-across justification report.

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

It is not apparent from the citing OECD SIDS (2005) review if an official test guideline was followed.

Groups of Wistar rats (10/sex) were exposed (nose-only) for 4 hours to sodium nitrite aerosols, generated from solutions in deionised water, at target concentrations of 10 or 100 mg/m3. Aerosols dried rapidly so animals were exposed to dry particulate test material. Mass mean aerodynamic diameter was 1.7 and 2.0 μm for the low and high groups respectively. Methaemoglobin levels were measured after exposure and the remaining animals maintained for 14 days, and then subject to a full post-mortem examination.

GLP compliance:

yes

Test type:

traditional method

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: not specified in citing OECD and ECB reviews
- Females (if applicable) nulliparous and non-pregnant: not specified in citing OECD and ECB reviews
- Age at study initiation: not specified in citing OECD and ECB reviews
- Weight at study initiation: not specified in citing OECD and ECB reviews
- Fasting period before study: not specified in citing OECD and ECB reviews
- Housing: not specified in citing OECD and ECB reviews
- Diet (e.g. ad libitum): not specified in citing OECD and ECB reviews
- Water (e.g. ad libitum): not specified in citing OECD and ECB reviews
- Acclimation period: not specified in citing OECD and ECB reviews

ENVIRONMENTAL CONDITIONS
- Temperature (°C): not specified in citing OECD and ECB reviews
- Humidity (%): approximately 60%
- Air changes (per hr): not specified in citing OECD and ECB reviews
- Photoperiod (hrs dark / hrs light): not specified in citing OECD and ECB reviews

IN-LIFE DATES: not specified in citing OECD and ECB reviews

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

not specified

Mass median aerodynamic diameter (MMAD):

ca. 1.7 - ca. 2 µm

Remark on MMAD/GSD:

Mass mean aerodynamic diameter was 1.7 and 2.0 μm for the low and high groups respectively. GSD was not specified in citing OECD and ECB reviews.

Details on inhalation exposure:

[No further details provided in citing OECD and ECB reviews]

Analytical verification of test atmosphere concentrations:

yes

Remarks:

High dose achieved 95.1 mg/m3

Duration of exposure:

4 h

Concentrations:

10 or 100 mg/m3 [high dose evidently achieved 95.1 mg/m3]

No. of animals per sex per dose:

10

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: not specified in citing OECD and ECB reviews
- Necropsy of survivors performed: yes
- Other examinations performed: methaemoglobin levels following exposure

Statistics:

[Not specified in citing OECD and ECB reviews]

Preliminary study:

[Not specified in citing OECD and ECB reviews]

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 100 mg/m³ air (nominal)

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No mortaility observed up to 14 days post exposure.

Clinical signs:

other: None specified [extent of assessment unclear from citing OECD and ECB reviews]

Body weight:

[Unclear if body weights assessed from citing OECD and ECB reviews]

Gross pathology:

None reported

Other findings:

"Methaemoglobin was significantly increased above concurrent control values only in females exposed to 10 mg/m3. However, the increase was judged to be not haematologically
significant as the value was within the range seen for control animals of this age. Further there was no significant increase in males. There were no toxicologically significant effects on animals maintained for 14 days post-exposure".

Interpretation of results:

study cannot be used for classification

Conclusions:

According to OECD (2005) and ECB (2000), briefly describing the findings of an unpublished GLP acute inhalation study, there was no mortality or other toxicologically significant adverse effects in rats (10/sex/group) during a14-day observation period following a 4-hr exposure to up to 100 mg/m3 of sodium nitrite. As such, a 4-hr LC50 of >100 mg/m3 can be concluded for sodium nitrite.

Executive summary:

According to OECD (2005) and ECB (2000), briefly describing the findings of an unpublished GLP acute inhalationstudy, groups of 10 male and 10 female Wistar rats were exposed nose only for 4 hours to sodium nitrite aerosols, generated from solutions in deionised water, at target concentrations of 0, 10 or 100 mg/m3 (and achieving 95.1 mg/m3). Aerosols dried rapidly so animals were exposed to dry particulate test material. Mass mean aerodynamic diameter was 1.7 and 2.0 μm for the low and high groups respectively. Methaemoglobin levels were measured following exposure. The remaining animals were maintained for 14 days, and then subject to a “full post-mortem examination”.

No mortality or other toxicologically significant adverse effects were reported. As such, a 4-hr LC50 of >100 mg/m3 can be concluded for sodium nitrite.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

No relevant acute toxicity human data were identified with calcium nitrite. 

 

The acute oral toxicity of calcium nitrite (anhydrous powder) was investigated in Sprague-Dawley rats, in a US EPA TSCA guideline study (essentially equivalent to OECD Test Guideline 401), conducted according to GLP. Animals (5/sex/group) were administered the test substance (dissolved in an unspecified vehicle, presumably water) by oral gavage at doses of 100, 200, 300 or 400 mg/kg bw, and observed for up to 14 days. The dose range used in the main test was informed by a preliminary test involving gavage administration at levels of 100, 300, 600, 900 or 1200 mg/kg bw to male rats (3/group). All animals died at the top dose (400 mg/kg bw) in the main test, while there were 2 and 5 deaths at the intermediate doses (200 and 300 mg/kg bw respectively). Deaths occurred within hours of test material administration and were attributed to asphyxiation. No mortality was observed in the low dose group (100 mg/kg bw). In the animals that died, clinical signs of toxicity were limited to discolouration (cyanosis) of the ears/feet, tremors and reduced respiration in certain animals in the 300 mg/kg bw dose group. Upon necropsy, toxic effects included moderate haemorrhaging of the stomach and small intestine as well as effects on the skin, liver and lungs. No significant lesions were observed in surviving animals. The acute oral LD50 was determined (using probit analysis) to be 283 mg/kg bw in rats (95% CL 233-343 mg/kg bw) (Olson, 1985).

 

In an EU Method B.1 bis (fixed dose procedure) study, to GLP, calcium nitrite (hydrate) was studied for acute toxicity after single oral administration in rats. The test substance (DCI), available as a 34% aqueous solution, was administered (diluted in water) to groups of rats (5/sex) by oral gavage at 50 mg/kg bw in the main study. The dose used in the main study was informed by a preliminary investigation involving gavage administration at 50 or 500 mg/kg bw to a single female rat in each case. In the preliminary study, death was only seen at 500 mg/kg bw. There was no mortality seen at 50 mg/kg bw in the preliminary or main test. Clinical signs were limited to piloerection in all rats, reversible within 2 days of administration. Treatment had no effect on growth and there were no macroscopic abnormalities. The discriminating dose of calcium nitrite (hydrate) following gavage administration to rats was established to be 50 mg/kg bw (McRae, 1996).

 

No relevant acute dermal or inhalation toxicity data were identified with calcium nitrite.

 

Sodium nitrite is closely related to calcium nitrite, and is considered a suitable surrogate for read-across for this endpoint. [See read-across justification report in IUCLID section 13 for details.]

According to OECD (2005) and ECB (2000) reviews, briefly describing the findings of an unpublished GLP acute inhalation study, groups of 10 male and 10 female Wistar rats were exposed nose only for 4 hours to sodium nitrite aerosols, generated from solutions in deionised water, at target concentrations of 10 or 100 mg/m3 (and achieving 95.1 mg/m3). Aerosols dried rapidly so animals were exposed to dry particulate test material. Mass mean aerodynamic diameter was 1.7 and 2.0 μm for the low and high groups respectively. Methaemoglobin levels were measured following exposure. The remaining animals were maintained for 14 days, and then subject to a “full post-mortem examination”. No mortality of other toxicologically significant adverse effects were reported (McLean-Head and Mould, 1985). As such, a 4-hr LC50 of >100 mg/m3 can be concluded for sodium nitrite.

 

Exposure via inhalation is very unlikely due to the low possibility of exposure to aerosols, particles or droplets of an inhalable size. Moreover, skin contact during production and/or use is not likely.

 

The critical adverse effect of exposure to nitrite is methaemoglobinaemia, a condition whereby methaemoglobin is formed in the blood due to the interaction of haemoglobin with nitrite (EFSA, 2017; Health Canada, 2013; IARC, 2010; OECD, 2005; WHO, 2011). Higher concentrations of methaemoglobin result in cyanosis, hypoxia and eventually death (EFSA, 2017).

 

The acute oral LD50 values for nitrite toxicity in experimental animals are within the lethal range reported for humans (about 30-250 mg/kg bw) (Health Canada, 2013; OECD, 2005).

 

References (not included in IUCLID ESRs)

 

Health Canada (2013). Guidelines for Canadian Drinking Water Quality: Guideline Technical Document – Nitrate and Nitrite. Catalogue No H144-13/2-2013E-PDF.http://healthycanadians.gc.ca/publications/healthy-living-vie-saine/water-nitrate-nitrite-eau/alt/water-nitrate-nitrite-eau-eng.pdf?_ga=2.222634333.774105563.1517223052-337288668.1517223052

 

IARC (2010). International Agency for Research on Cancer. Ingested nitrate and nitrite and cyanobacterial peptide toxins. IARC Monographs on the Evaluation of Carcinogenic Risk to Humans. Volume 94, 14-21 June 2006.http://monographs.iarc.fr/ENG/Monographs/vol94/mono94.pdf

 

WHO (2011). World Health Organization. Nitrate and nitrite in drinking water. Background document for development of WHO guidelines for drinking-water quality. WHO/SDE/WSH/07.01/16/Rev/1.http://www.who.int/water_sanitation_health/dwq/chemicals/nitratenitrite2ndadd.pdf

Justification for classification or non-classification

Based on the results of the available and reliable acute oral rat study (Olson, 1985), calcium nitrite should be classified for acute oral toxicity (category 3) according to EU CLP criteria (EC 1272/2008).

 

Deaths in the critical rat study were attributed to asphyxiation. Although not explicitly discussed by the investigators, this was likely a result of methaemoglobinaemia, a well-established response to nitrite exposure (in both humans and experimental animals), particularly given the observation of cyanotic effects in surviving animals. As such, and in line with ECHA (2017) guidance, the criteria for STOT-SE

classification are not fulfilled since the methaemoglobin formation is likely causative for the observed lethality and calcium nitrite is accordingly classified in the appropriate acute toxicity hazard class.

 

References (not included in IUCLID ESRs)

 

ECHA (2017). European Chemicals Agency. Guidance on the Application of the CLP Criteria. Guidance to Regulation (EC) No 1272/2008 on classification, labelling and packaging (CLP) of substances and mixtures. Version 5.0. July 2017.https://echa.europa.eu/documents/10162/23036412/clp_en.pdf/58b5dc6d-ac2a-4910-9702-e9e1f5051cc5