Calcium nitrate

Endpoint summary

Description of key information

A reliable study with calcium nitrate is not available. Based on an expert statement, a sub-chroning repeated dose toxicity study does not need to be conducted.

A OECD 407 study with the read-across substance Nitcal-K (potassium pentacaclium nitrate decahydrate) and an OECD 422 study with potassium nitrate did not show any adverse effects up to the highest dose level tested (1000 and 1500 mg/kg bw/day, respectively). The read-across rationale can be found in the document attached to the appropriate target record and is incorporated fully in the CSR (see Appendix A).

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The study was performed with a substance analogue and the data are read across.

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River, Sulzfeld, Germany
- Age at study initiation: 6 weeks
- Weight at study initiation: males: 195-227 g; females: 154-181 g
- Fasting period before study: no
- Housing: group housing (5/sex) in Macrolon cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-23
- Humidity (%):31-73
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 9 February 2007 To: 9 March 2007

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:

DIET PREPARATION
- Rate of preparation of diet (frequency): once
- Mixing appropriate amounts with (Type of food): not applicable
- Storage temperature of food: not indicated

VEHICLE
- Justification for use and choice of vehicle (if other than water): based on trial formulations
- Concentration in vehicle: 5, 10, 100 mg/ml
- Amount of vehicle (if gavage): 10 ml/kg body weight
- Lot/batch no. (if required): not applicable
- Purity: Water (Milli-U) (millipore Corporation, Bedford, USA

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

homogeneity (high- and low dose) and concentration (all doses) were analysed

Duration of treatment / exposure:

28 days

Frequency of treatment:

Daily

Remarks:

Doses / Concentrations:
50, 150, 1000 mg/kg bw
Basis:
actual ingested

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Dose selection rationale: based on an 8-day dose range finding study (NOTOX project 482737)

Positive control:

no

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: No

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: at least once daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: not indicated (subjective appraisal)

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: day of necropsy
- Anaesthetic used for blood collection: Yes (iso-flurane)
- Animals fasted: Yes
- How many animals: all animals
- Parameters examined. standard parameters

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: day of necropsy
- Animals fasted: Yes
- How many animals: all animals
- Parameters checked in table [No.?] were examined.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: during treatment week 4
- Dose groups that were examined: all animals
- Battery of functions tested: hearing ability / grip strength / motor activity / righting reflex/ pupillary reflex:

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes, all selected tissues from control and high dose animals, gross lesions (all animals), stomach and spleen (all dose levels)

Other examinations:

Organ weights

Statistics:

Yes

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

HAEMATOLOGY: high-dose males: reticulocytes and red cell distribution width slightly increased; high-dose females: red blood cell count and haematocrit slightly decreased. Reviewer: these changes are not consistent between males/females, are very slight, and three out of four appeared to be in the historical control range from this strain (based on NOTOX historical data) and this kind of study. Therefore, not considered adverse.

GROSS PATHOLOGY: thickened limiting ridge and/or foci in glandular mucosa in 2 and 3 high-dose males and females, respectively. This is a local effect and reversible.

HISTOPATHOLOGY: NON-NEOPLASTIC: hyperplasia/hyperkeratosis of the limiting ridge of the stomach in 4 and 3 high dose males and females, respectively; increased severity of haemopoietic foci (erythroid) in the spleen at high dose. Reviewer: The effect in the stomach is a local effect and reversible. The effect in the spleen is limited to one male and one female with a moderate severity at the high dose. However, this is a symptom expected in young animals in such a study, in addition it is considered a reversible effect. This is based on expertise of experienced pathologist.

Key result

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Author considered 150 mg/kg bw as a NOAEL, however no adverse effects at highest dose tested according to reviewer. See discussion.

Critical effects observed:

not specified

The treatment-related changes in hematology parameters and spleen morphology at high dose point a slightly increased red blood cell turnover

Conclusions:

Based on effects noted at high dose (1000 mg/kg body weight/day), the NOAEL of Nitcal/K was considered tobe 150 mg/kg body weight/day in a 28-day oral (gavage) study in rats

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The study has been performed according to OECD and/or EC guidelines and according to GLP principles. However, since the study was performed with a substance analogue and the data are read across, the Klimisch score is 2.

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Oral

No study with the substance itself is available.

A reliable 28 -day oral OECD 407, EU B.7 guideline study has been performed in rats (5 rats/sex/dose) via gavage, containing 50, 150 or 1000 mg/kg bw/day Nitcal-K (potassium pentacalcium nitrate decahydrate). There were no treatment-related deaths and no signs of overt clinical toxicity. There were no effects on body weight, food consumption, or food efficiency. Functional observational battery (FOB) and motor activity tests identified no treatment-related changes in behavior, function, or motor activity. In haematology high-dose males reticulocytes and red cell distribution width were slightly increased; in high-dose females red blood cell count and haematocrit was slightly decreased. Reviewer: these changes are not consistent between males/females, are very slight, and three out of four appeared to be in the historical control range from this strain (based on NOTOX historical data) and this kind of study. Therefore, these are not considered adverse. At gross pathology a thickened limiting ridge and/or foci in glandular mucosa in 2 and 3 high-dose males and females, respectively, were noted. This is a local effect and reversible. At histopathology some non-neoplastic effects were observed: hyperplasia/hyperkeratosis of the limiting ridge of the stomach in 4 and 3 high dose males and females, respectively. This is considered a local effect and reversible according to the reviewer. In addition an increased severity of haemopoietic foci (erythroid) in the spleen at high dose was noted. Reviewer: The effect in the spleen is limited to one male and one female with a moderate severity at the high dose. However, this is a symptom expected in young animals in such a study, in addition it is considered a reversible effect. This is based on expertise of an experienced pathologist. Therefore, it was concluded that the NOAEL is >=1000 mg/kg bw/day (highest dose tested).

 

In addition, a combined repeated dose toxicity study with a reproduction/ developmental toxicity screening performed according to OECD 422 guideline and GLP principles was performed with potassium nitrate. Male and female rats were exposed to 0, 250, 750 or 1500 mg/kg bw/ day. There were no treatment-related deaths and no signs of overt clinical toxicity. There were no effects on body weight, food consumption, or food efficiency, haematology, clinical chemistry. No effects on organ weights or upon macroscopic or microscopic examination were found. Based on these data, the NOAEL of potassium nitrate was found to be >=1,500 mg/kg/day for general toxicity.

No dermal and inhalation toxicity studies are available. Inhalation exposure seems to be an unlikely route of exposure as the vapour pressure is assumed to be very low and the particle size of the substance is high (in the case of calcium nitrate 2% < 100 µm, which is the inhalable fraction).

Based on an expert statement, no additional studies with Calcium nitrate are performed. In the 28-day study at the limit dose value of 1000 mg/kg bw/day no adverse toxicity is seen. In addition, in an OECD 422 study no toxicity is seen at the limit dose of 1500 mg/kg bw/day. Based on the assessment factors for exposure duration (see guidance IR CSA R.8) from subacute to semi-chronic a factor 3 is used, expecting a 3 times lower NOAEL. Assuming this factor would be applicable for this substance, this would still not result in a NOAEL showing a hazardous property. In addition, all supporting data, sub-chronic, chronic, carcinogenicity, included do not suggest any hazardous properties of the substsance. Calcium nitrate dissociates into Ca2+ and nitrate ions. Nitrates are regulated within the body. Ca2+ is a necessary element of which the accepted daily dose is 1-2.5 g/day (Dutch Voedingscentrum). Based on this weight of evidence, no sub-chronic study is considered required.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:

One 28-day study on the read-across substance Nitcal/K is available.

Justification for classification or non-classification

Based on the data available, calcium nitrate does not have to be classified according to the CLP Regulation for repeated dose toxicity.