Hydrazine

Endpoint summary

Description of key information

In a sub-acute toxicity study according to OECD TG 407 hydrazine monohydrate was administered to male and female Crj:CD(SD)IGS rats by gavage at dose levels of 0, 1, 3, 10, 30 mg/kg bw/day; the NOAEL is 3 mg/kg bw/day for males and female rats (MHLW 2003). Assuming that hydrazine monohydrate contains 64 % hydrazine unhydrous the respective NOAEL is 1.92 mg/kg bw/day. There is a long term inhalation study on rats, and other animals which is reported in brief. The used concentration for rats ranged between 0.05 and 5 ppm (0.066 -6.65 mg/m³) hydrazine for 6 h per day, 5 days per week for 1 year. With respect to non-neoplastic lesions in rats the LOAEC is 0.066mg/m³ (MacEwen 1981, Vernot 1985) based on local effects at the respiratory tract..

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:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: guidelinestudy, GLP

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

a 14-day recovery period : control and high dose animals

Principles of method if other than guideline:

Guideline for the 28-day repeated dose toxicity test in mammalian species (Chemical Substances Control Law of Japan)

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Crj: CD (SD)IGS

Sex:

male/female

Details on test animals or test system and environmental conditions:

as required by guideline

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

After the 28 day treatment period a 14-day recovery period is reported for the control and the highest test group.

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

no given

Duration of treatment / exposure:

28 d

Frequency of treatment:

daily

Remarks:

Doses / Concentrations:
0, 1, 3, 10, 30 mg/kg bw/day (corresponding to 0, 0.64-19.2 mg/kg bw/d hydrazine)
Basis:

No. of animals per sex per dose:

5 males and 5 females/per dose group including control animals

Control animals:

yes, concurrent vehicle

Details on study design:

Post-exposure period: 14 d

Positive control:

no

Observations and examinations performed and frequency:

clinical signs, food comsumption, body weight, hematology, blood chemistry, urinalysis

Sacrifice and pathology:

all animals were autopsied
rel and absolute organ weight, gross findings, histopathological findings

Other examinations:

no further information

Statistics:

Appropriate statistical methods were used: eg. non-parametric analysis (no further information)

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Food efficiency:

effects observed, treatment-related

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

see section remarks on results

Dose descriptor:

NOAEL

Effect level:

3 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: (corresponding to 1.92 mg/kg bw/d) based on adverse effects from 10 mg/kg bw/d onwards including changes in hematology, blood chemistry and changes in liver, spleen and kidneys

Critical effects observed:

not specified

CLINICAL OBSERVATIONS AND FREQUENCY:
-Mortality:
No deaths were observed
-Clinical signs:
30 mg/kg bw/d:
males+females: wasting, piloerection, salivation;
females: dirty nasal discharge
30 mg/kg bw/d (males and females):
-Body weight gain, food consumption, food efficiency suppressed, reversable during recovery

--HEMATOLOGY (significant changes)
-------males, 30 mg/kg bw:
significant decrease:
HCT: 38.0 % vs 44.8 % of control; recovery in 14 d
HGB: 11.9 g/dL vs 15.1 g/dL of control; recovery in 14 d
MCV: 51.8 µm3 vs 57.3 µm3 of control; recovery in 14 d
MCH: 16.2 pg vs 19.6 pg of control; recovery in 14 d
MCHC: 31.3 % vs 34.2 % of control
PT: 14.4 sec vs 17.5 sec of control; recovery in 14 d
APTT: 19.6 sec 24.2 sec of control; recovery in 14 d
significant increase but recovery in 14 d:
Reticulocytes: 6.2 % vs 2.8 % of control;
Methemoglobin: 0.99 % vs 0.75 % of control;
PLT count: 1786 10³/mm3 vs 1304 10³/mm3 of control
------females,
---from 10 mg/kg bw onwards significant decrease but recovery in 14 d
HCT: 40.5 %, 34.7 % % vs 43.6 % of control;
HGB: 14.0 g/dL, 10.6 g/dL vs 15.3 g/dL of control;
MCH: 18.7 pg, 16.6 pg vs 19.7 pg of control;
---30 mg/kg bw significant dercrease
RBC: 6.43x10[exp6]/mm³ vs 7.77 x10[exp6]/mm³of control; recovery in 14 d
MCHC: 30.7 % vs 35.1 % of control
---30 mg/kg bw significant increase but recovery in 14 d:
Reticulocytes: 9.2 % vs 2.2 % of control;
Methemoglobin: 1.0 % vs 0.52 % of control

--CLINICAL CHEMISTRY (significant changes):
------Male, 30 mg/kg bw but recovery in 14 d
Glucose (mg/dL): 100 vs. 140 of control
BUN (mg/dL): 22.5 vs. 13.7 of control
Tbilirubin (mg/dL): 0.12 vs. 0.04 of control
Albumin (g/dL): 3.86 vs. 3.60 of control
A/G ratio : 2.37 vs. 1.80 of control
Chloride (mmol/L): 104.6 vs. 108 of control
Iphosphate (mg/dL): 9.54 vs. 8.05 of control
AST (U/L): 51 vs. 77 of control
ALT (U/L): 17 vs. 32 of control
------female, at 10 mg/kg bw but recovery in 14 d
AST (U/L): 62 vs. 73 of control
ALT (U/L): 17 vs. 25 of control
------female, 30 mg/kg bw but recovery in 14 d
Glucose (mg/dL): 83 vs. 114 of control
Tbilirubin (mg/dL): 0.11 vs. 0.03 of control
A/G ratio : 2.42 vs. 1.77 of control
Chloride (mmol/L): 102 vs. 108 of control
Calcium (mg/dL): 10.49 vs. 9.74 of control
Iphosphate (mg/dL): 9.81 vs. 7.56 of control

----------GROSS AND HISTOPATHOLOGY
---The absolute weights of
the kidneys were increased or tended to be increased in both sexes of the 10 and 30 mg/kg bw groups; elevation of liver weights in females of the 10 and 30 mg/kg bw groups and of spleen weights in 30 mg /kg bw females was apparent.
---Relative weights of
the liver and kidneys were higher or tended to be higher in both sexes of the 10 and 30 mg/kg bw groups than in controls. liver males: 3.01%,3.5% versus 2.7%, recovery in 14 d liver females: 3.2%,3.9% versus 2.7%, after 14d: 3.2% versus 2.7% kidneys males: 0.84%,1.04 versus 0.76%, recovery in 14 d kidneys females: 0.86%, 0.96% versus 0.79%, after 14 d: 0.85% versus 0.75%
---Macroscopically,
pale colored livers were observed in both sexes of the 30 mg/kg bw group.
---Histopathologically,
fatty change of the hepathocytes was observed in males of the 10 and 30 mg/kg bw groups and in females of all groups including the controls. Pigmentation of the spleen was observed in both sexes of the 30 mg/kg bw group. A higher degree of extramedullary hematopoiesis than normal was observed in both sexes of the 30 mg/kg bw group and in males of the 10 mg/kg bw group.

Executive summary:

In a subacute toxicity study according to OECD TG 407 hydrazine monohydrate was administered to male and female Crj:CD(SD)IGS rats by gavage at dose levels of 0, 1, 3, 10, 30 mg/kg bw/day diluted in water. Additionally, the control group and the highest dose group were observed during a 14-day recovery period (MHLW 2003). Based on adverse effects from 10 mg/kg bw/d onwards including changes in hematology, blood chemistry and changes in liver, spleen and kidneys the NOAEL is 3 mg/kg bw/day for male and female rats.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

1.92 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The only available study which is performed according to the actual guideline and under GLP conditions. Therefore the study was evaluated with Klimisch score 1

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: inhalation

Remarks:

other: 1 Year exposure and add observation period lifelong

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: evaluation of histopatological changes only

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

Method: exposure of rat, mouse, hamster, dog for 1 year and post exposure observation for 18 months (rat), 15 months (mouse), 12 months (hamster) and 38 months (dog), respectively.

GLP compliance:

not specified

Limit test:

no

Species:

other: rat, mouse, hamster, dog

Strain:

other: F344 rat; C57BL/6 mouse, Golden Syrian hamster, Beagle dogs

Sex:

male/female

Details on test animals or test system and environmental conditions:

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22
- Humidity (%): 50
-

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

other: air

Remarks on MMAD:

MMAD / GSD: no data

Details on inhalation exposure:

inhalation exposures were conducted 6 hr/day, 5 days/week for 1 year without exposures on weekend and holidays

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Technico Autoanalyser proportioning pump and colorimeter

Duration of treatment / exposure:

12 mo

Frequency of treatment:

6 h per d, 5 d a week, not during holidays (not specified)

Remarks:

Doses / Concentrations:
0, 0.05 - 5.0 ppm (0, 0.066-6.65 mg/m³)
Basis:

No. of animals per sex per dose:

100 male and 100 female rats/conc. 0.066, 0.33, 1.33, 6.65 mg/m³: post exposure observation: 18 months
400 female mice/conc.0.066, 0.33, 1.33 mg/m³; post exposure observation: 15 months
200 male hamsters/conc. 0.33, 1.33, 6.65 mg/m³ post exposure observation: 12 months
4 males and 4 female dogs/conc. 0.33. 1.33 mg/m³ post exposure observation: 38 months

Control animals:

yes, concurrent no treatment

Details on study design:

Post-exposure period: 12 mo hamsters, 18 mo rats, 15 mo mice, 38 mo dogs

Positive control:

no

Observations and examinations performed and frequency:

clinical signs of toxicology body weight development biweekly (10 mice/cage as cage groups),
hematology and clinical chemistry of dogs biweekly,

Sacrifice and pathology:

all animals that died or were killed during the study were necropsied: external examination and complete histopathological examination

Other examinations:

no further data

Statistics:

yes: t-test, Fisher's exact test,

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

effects observed, treatment-related

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

effects observed, treatment-related

Details on results:

see remarks on results

Dose descriptor:

LOAEC

Effect level:

0.066 mg/m³ air

Sex:

male/female

Basis for effect level:

other: Rat: based on inflammatory changes and squamous metaplasia in the nose, larynx and trachea most prominent at the highest test dose

Dose descriptor:

LOAEC

Effect level:

0.33 mg/m³ air

Sex:

male

Basis for effect level:

other: hamster: based on generalized amyloidosis in the liver, kidneys, thyroid and adrenal glands significantly greater frequency than in control animals

Dose descriptor:

NOAEC

Effect level:

0.33 mg/m³ air

Sex:

male/female

Basis for effect level:

other: dog: based on focal areas of highly vacuolated liver cells and a corresponding elevation in SGPT (data not shown)

Dose descriptor:

NOAEC

Effect level:

6.65 mg/m³ air

Sex:

female

Basis for effect level:

other: mouse: no non-neoplastic lesions

Critical effects observed:

not specified

Variance in exposure concentration mainly +/-10%; neoplastic lesions see chapter carcinogenicity; significantly reduced body weight gain in male and female rats (but not dose-dependent), most
significant in male rats at 5 ppm, in male hamsters at all doses during exposure (only at 5 ppm in the final mo); no effects on weight gain in female mice; mortality in mice and rats not significant different from controls, in unexposed hamsters lowered number of deaths during exposure compared to all treated hamsters (no data about significance); histopathology of rodents found dead or sacrified at termination of post exposure period (10% of surviving rats were nercopsied after 12 mo post exposure period) showed following alterations, significantly different from controls:
hamsters: liver amyloidosis and hemosiderosis, bile duct hyperplasia, spleen amyloidosis, lymphadenitis, kidney interstitial and glomerular amyloidosis, adrenal amyloidosis, senile atrophy of the testis;
female rats: tracheal inflammation, hepatic hyperplasia at 1 and 5 ppm; only significant in high dose group: nasal squamous and epithelial metaplasia, inflammation and squamous metaplasia of the larynx, tracheal squamous metaplasia, lymph node hyperplasia, glomerulonephritis, cystic endometrial hyperplasia, endometritis, salpingitis, atrophy of ovar;
male rats: myocardial degeneration; only significant in high dose group: nasal meta- and hyperplasia, laryngeal squamous metaplasia, interstitial hyperplasia of the testis; no significant histopathological alterations in mice and dogs; no further treatment related, significant effects in dogs.

Executive summary:

There is a longterm study on rats, mice, hamsters and dogs which is reported in brief. The used concentration for rats ranged between 0.05 and 5 ppm (0.066 -6.65 mg/m³) hydrazine, for mice between 0.05 and 1.0 ppm (0.066-1.33 mg/m³) and for hamsters between 0.25 and 5.0 ppm (0.33-6.65 mg/m³) The exposure period was 6 h per day, 5 days per week for 1 year (but not during holidays, not specified) followed by a lifelong post exposure observation period (MacEwen 1981, Vernot 1985). With respect to the non-neoplastic lesions

in rats the LOAEC is 0.066 mg/m³ based on dose-dependent increase in inflammatory changes and

squamous metaplasia in the nose, larynx and trachea

in hamster the LOAEC is 0.33 mg/m³ based on generalized amyloidosis in the liverm , kidneys,thyroid and adrenal glands significantly greater frequency than in control animals

in dogs the NOAEC is 0.33 mg/m³ based on focal areas of highly vacuolated liver cells and a corresponding elevation in SGPT (data not shown)

in mouse the NOAEC is 6.65 mg/m³ because no non-neoplasic lesions were reported

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEC

0.066 mg/m³

Study duration:

chronic

Species:

rat

Quality of whole database:

There is a longterm study using the most relevant exposure route and therefore evaluated with Klimisch score 2. in this study rats revealed to be the most sensitive species because they developed irritational effects in nose, larynx and trachea already from the lowest concentration in test of 0.066 mg/m³ onwards. Thus, the local irritational findings in rats are the predominant effects after long term exposure. Therefore, only a local long term threshold is defined.

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

Dermal route

There is no study using the dermal application route. There is a reliable subacute (28-days) oral study available and a reliable longterm study using the inhalation route of exposure. Thus, there are studies available using the appropriate application route and the requirements of ANNEX VIII are fulfilled. In addtion, hydrazine is known to be corrosive.

Oral route

In a subacute toxicity study according to OECD TG 407 hydrazine monohydrate was administered to male and female Crj:CD(SD)IGS rats by gavage at dose levels of 0, 1, 3, 10, 30 mg/kg bw/day diluted in water. Additionally, the control group and the highest dose group were observed during a 14-day recovery period (MHLW 2003). Anemia and methemoglobinemia, elevated serum levels of total bilirubin, albumin globulin ratio (A/G) inorganic phosphorus and reduced glucose and chloride levels in both sexes, increase in the Blood Urea Nitrogen (BUN) and albumin values in males and calcium in females were noted. Macroscopically the absolute and relative weight-increase in liver, spleen and kidneys and histopathologically fatty change of the hepatocytes were observed. Based on these adverse effects from 10 mg/kg bw/d onwards the NOAEL is 3 mg/kg bw/day for male and female rats. Assuming that hydrazine monohydrate solution contains 64 % hydrazine unhydrous, the respective NOAEL is 1.92 mg/kg bw/d.

In longterm toxicity studies rats (Steinhoff 1988) and mice (Steinhoff 1990) received 0,2, 10, or 50 ppm hydrazine in their drinking water. However in both studies no clinical chemistry, hematology or urinalysis data were measured and only mortality data, weight development and tumour development were reported. Thus, these studies do not fulfill the requirement of a repeated dose toxicity study and were therefore not taken into account in the assessment of repeated dose toxicity. (With respect of the assessment of carcinogenic effects see the respective section).

Inhalation route

There is a longterm inhalation study on rats, mice, hamsters and dogs which is reported in brief. The used concentration for rats ranged between 0.05 and 5 ppm (0.066-6.65 mg/m³) hydrazine, for mice between 0.05 and 1.0 ppm (0.066-1.33 mg/m³) and for hamsters between 0.25 and 5.0 ppm (0.33-6.65 mg/m³). The exposure period was 6 h per day, 5 days per week for 1 year (but not during holidays, not specified) followed by a lifelong post exposure observation period (MacEwen 1981, Vernot 1985). With respect to non-neoplastic lesions in hamster the LOAEC is 0.33 mg/m³ based on generalized amyloidosis in the liver, kidneys, thyroid and adrenal glands with a significantly greater frequency than in controls; in dog the NOAEC is 0.33 mg/m³ based on focal areas of highly vacuolated liver cells and a corresponding elevation of SGPT values (data not shown), in mouse the NOAEC is 1.33 mg/m³ because no non-neoplastic lesions were reported. In rats, non-neoplastic changes in the respiratory tract (inflammatory changes and squamous metaplasia in the nose, larynx and trachea) were shown even at the lowest concentration of 0.066 mg/m³ (0.05 ppm), but the response showed no clear dose-response relationship especially at 0.25 and 1 ppm; clear effects were demonstrated at 5 ppm. The reason for the lack of dose-response relationship can not be elucidated based on the available publication and study report (Vernot et al 1985, MacEwen et al 1981) but taking into account the known highly irritating or even caustic property of hydrazine to the skin and mucous membranes it can be assumed that a direct cytotoxic mechanism is most probabely dominant and local toxicity is regarded to be of main importance with tumour development as secondary response.

The database is not fully conclusive regarding the local irritation potential at the respiratory tract and the mode of action that leads to the tumour response in animal studies, e.g. the carcinogenic effects of hydrazine have been shown only with maximally tolerated unambiguously toxic doses or locally irritating concentrations and there is no clear dose response relationship for local irritation effects at the respiratory tract.

That reflection of the database led industry initially to propose to strengthen the database with a testing proposal to examine the irritation threshold after repeated inhalation with the aim to define the most sensitive level of the respiratory tract after repeated exposure, as well as the threshold for irritation after repeated exposure and on the respective dose-response relationship.

Based on responses received from the Competent Authorities that proposal was revised taking into consideration the following aspects:

• According to DIRECTIVE (EU) 2017/2398 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 12 December 2017  amending Directive 2004/37/EC on the protection of workers from the risks related to exposure to carcinogens or mutagens at work the binding limit value for occupational exposure is 0.013 mg/m³.

• The scientific and regulatory value for further toxicological testing needs to be weighted with animal welfare considerations.

Based on these considerations the testing proposal for a short-term repeated dose toxicity study via the inhalation route was deleted.

Therefore scientific uncertainties remain, but whereas the Binding Limit Value will be 0.013 mg/m³ the LOAEC for irritation at the respiratory tract is 0.066 mg/m³ and therefore higher than the Binding Limit Value. By that, even if there are uncertainties regarding the no effect level for irritation it is assumed that the Binding Limit Value covers also the aspect of non-neoplastic lesions including local irritation.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
The only available study which is performed according to the actual guideline and under GLP conditions. Therefore the study was evaluated with Klimisch score 1

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
There is a long term study using the most relevant exposure route and therefore evaluated with Klimisch score 2. In this study rats revealed to be the most sensitive species because they developed local effects (irritational effects in nose, larynx and trachea ) already from the lowest concentration in test of 0.066 mg/m³ onwards. Thus, the local irritational findings in rats are the predominant effects after long term exposure. Therefore, only a local long term threshold is defined.

Justification for selection of repeated dose toxicity inhalation - local effects endpoint:
There is a long term study using the most relevant exposure route and therefore evaluated with Klimisch score 2. In this study rats revealed to be the most sensitive species because they developed irritational effects in nose, larynx and trachea already from the lowest concentration in test of 0.066 mg/m³ onwards. Thus, the local irritational findings in rats are the predominant effects after long term exposure. Therefore, only a local long term threshold is defined.

Justification for classification or non-classification

Under Regulation No 1272/2008 (GHS) the substance is not classified.

The available data are conclusive but not sufficient for classification as acute irritation to the respiratory tract is the most sensitive effect which is already covered by the classification on acute toxicity and corrosivity.