Calcium cyanamide

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

other information

Study period:

1996

Reliability:

other: The reliability of the original study report and endpoint record is Klimisch 2, but as read-across for this endpoint is not supported, Klimisch rating is not applied. For justification against read-across see “Justification for type of information”.

Rationale for reliability incl. deficiencies:

other: Justification for reliability see “Justification for type of information”

Justification for type of information:

The study was conducted with cyanamide, which is considered an analogue substance to calcium cyanamide. However, for this specific endpoint, read-across from cyanamide to calcium cyanamide is not necessary. In accordance with Column 2 of REACH Annex IX, the test repeated dose toxicity after inhalation does not need to be conducted as repeated dose toxicity studies for oral application are available. This endpoint study record is nevertheless copied to the calcium cyanamide dossier to demonstrate full consideration of all cyanamide study data in the substance assessment and classification of calcium cyanamide.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: Gaitonde committee guidelines

Deviations:

no

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

Deviations:

yes

Remarks:

, only 3 animals of each sex of the intermediate dose groups; actual concentration spaces are to narrow between the low and mid dose groups, satellite group.

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Cyanamide

EC Number:

206-992-3

EC Name:

Cyanamide

Cas Number:

420-04-2

Molecular formula:

CH2N2

IUPAC Name:

cyanamide

impurity 1

Reference substance name:

Cyanoguanidine

EC Number:

207-312-8

EC Name:

Cyanoguanidine

Cas Number:

461-58-5

Molecular formula:

C2H4N4

IUPAC Name:

2-cyanoguanidine

additive 1

Reference substance name:

Water

EC Number:

231-791-2

EC Name:

Water

Cas Number:

7732-18-5

Molecular formula:

H2O

IUPAC Name:

Dihydrogen oxide

additive 2

Reference substance name:

Orthophosphoric acid

EC Number:

231-633-2

EC Name:

Orthophosphoric acid

Cas Number:

7664-38-2

Molecular formula:

H3O4P

IUPAC Name:

phosphoric acid

Test material form:

liquid - solid: mixture of

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

head only

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: Particles generated size: < 5 µm in diameter

Details on inhalation exposure:

The aerosol of the test substance was generated by infusing it through the nebulizer which generates particles less than 5 µm in diameter. During the exposure, samplings of the atmosphere from the inhalation chamber were done for the HPLC determination of actual concentrations of Hydrogen cyanamide.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

During the exposure, samplings of the atmosphere from the inhalation chamber were done for the HPLC determination of actual concentrations of Hydrogen cyanamide.

Duration of treatment / exposure:

2 weeks

Frequency of treatment:

a daily treatment: 6 hours/ per day

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
2.5, 5 and 9.375 g/m³ of Hydrogen cyanamide
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0.1484 (range 0.0848-0.1916), 0.2629 (range 0.1489-0.3270) and 0.7991 (range 0.4080-1.1184) mg/L air
Basis:
analytical conc.

No. of animals per sex per dose:

10 rats (5 males and 5 females) were exposed to the low and high doses whereas 16 rats (8 males and 8 females) were exposed to the intermediate dose. An additional group of 8 males and 8 females served as the concurrent control group.

Control animals:

yes, concurrent no treatment

Details on study design:

On day 15 after start of the exposure 5 males and 5 females of each group were necropsied. The remaining animals (3 males and 3 females) of the control and intermediate dose group were maintained without any exposure for a further period of 2 weeks (satellite group, to investigate recovery).

Positive control:

No positive control

Examinations

Observations and examinations performed and frequency:

Animals were observed daily for mortality and/or moribundity and on hourly basis during exposure for toxic symptoms. Body weight and food consumption measurements were performed daily. Clinical pathology parameters (haematology and clinical chemistry) were determined in rats after 15 days of exposure in the main groups and after 29 days in the animals of the satellite group (control and intermediate dose).

Sacrifice and pathology:

On day 15 after start of the exposure 5 males and 5 females of each group were necropsied. The remaining animals (3 males and 3 females) of the control and intermediate dose group were maintained without any exposure for a further period of 2 weeks (satellite group, to investigate recovery). After the scheduled exposure regimen all animals of the low and high dose group and 5 males and 5 females each from the control and intermediate group and on day 29 the remaining animals were necropsied and the lesions were noted grossly. Organ weight evaluations (absolute and relative) and histopathological examination were performed on all animals. The same procedure was performed in the remaining animals at day 29.

Statistics:

The difference in body weight and organ weight between the animals of the control groups and the test substance treated groups was examined by the Student´s test criteria, p< 0.01 or p<0.05.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

No mortality was observed in rats belonging to any of the groups throughout the study period. No clinical signs of toxicity were found in rats exposed to Hydrogen cyanamide.

Statistically significantly decreased body weight could be observed for all treatment groups. However, the reduction in the males showed no dose-response-relationship. The extent of body weight decrease was below 10 % for the low and high dose males as well as for the low dose females. Subsequently to a withdrawal period of another 14 days, the body weights of the satellite group (mid dose animals) were in the control range (5 % below the body weight of controls) indicating a clear recovery. Consequently, the findings in low and mid dose are considered to be not adverse.

Total food consumption was not mentioned. Clear substance-related effects were not seen in food consumption. No compound-related effects were found in haematological and blood chemistry parameters.

Several absolute and relative organ weights in all treated groups in males and females were statistical significant different from the control group.In the satellite group the absolute and relative liver and kidney was still increased in male animals. In female animals an increase in absolute and relative lung weight and an increase in relative kidney weight was obtained.

Gross pathological lesions were observed in animals of all dose groups including the controls.

Histopathological changes revealed consistent recurring lesions in the brain, liver, heart and lungs in the high dose group in both sexes.

Effect levels

Dose descriptor:

NOAEL

Effect level:

0.26 mg/L air

Sex:

male/female

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

No remarks

Applicant's summary and conclusion

Conclusions:

NOAEL (rat, inhalation): 0.26 mg/L / 0.2629 g/m³ (analytical concentration; active ingredient)

Executive summary:

In a subacute inhalation study, Dormex (Hydrogen cyanamide, 50 % w/w formulation) was administered by inhalation (head only exposure) to male and female Wistar rats for 14 days. The nominal concentrations of the active ingredient, Hydrogen cyanamide were 2.5, 5 and 9.375 g/m³ to which the low, the intermediate and high dose group were exposed. 10 rats (5 males and 5 females) were exposed to the low and high doses whereas 16 rats (8 males and 8 females) were exposed to the intermediate dose. An additional group of 8 males and 8 females served as the concurrent control group. The aerosol of the test substance was generated by infusing it through the nebulizer which generates particles less than 5µm in diameter. During the exposure, samplings of the atmosphere from the inhalation chamber were done for the HPLC determination of actual concentrations of Hydrogen cyanamide. Animals were exposed for 6 hours per day, 5 days a week for 2 weeks. On day 15 after start of the exposure 5 males and 5 females of each group were necropsied. The remaining animals (3 males and 3 females) of the control and intermediate dose group were maintained without any exposure for a further period of 2 weeks (satellite group, to investigate recovery). After the scheduled exposure regimen all animals of the low and high dose group and 5 males and 5 females each from the control and intermediate group and on day 29 the remaining animals were necropsied and the lesions were noted grossly. Organ weight evaluations (absolute and relative) and histopathological examination were performed on all animals. The same procedure was performed in the remaining animals at day 29.

No mortality was observed in rats belonging to any of the groups throughout the study period. No clinical signs of toxicity were found in rats exposed to Hydrogen cyanamide.

Statistically significantly decreased body weight could be observed for all treatment groups. However, the reduction in the males showed no dose-response-relationship. The extent of body weight decrease was below 10 % for the low and high dose males as well as for the low dose females. Subsequently to a withdrawal period of another 14 days, the body weights of the satellite group (mid dose animals) were in the control range (5 % below the body weight of controls) indicating a clear recovery. Consequently, the findings in low and mid dose are considered to be not adverse.

Total food consumption was not mentioned. Clear substance-related effects were not seen in food consumption. No compound-related effects were found in haematological and blood chemistry parameters.

Several absolute and relative organ weights in all treated groups in males and females were statistical significant different from the control group.In the satellite group the absolute and relative liver and kidney was still increased in male animals. In female animals an increase in absolute and relative lung weight and an increase in relative kidney weight was obtained.

Gross pathological lesions were observed in animals of all dose groups including the controls.

Histopathological changes revealed consistent recurring lesions in the brain, liver, heart and lungs in the high dose group in both sexes.

Considering the lack of dose-response-relationship in the males and the recovery in the mid dose group, the NOAEL should be the mid dose, i.e. 0.26 mg/L.