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Administrative data

Description of key information

All the studies located indicated similar signs of toxicity after repeated administration of hydroxylammonium nitrate or an analogue namely: methaemaglobinaemia and haemolytic anaemia with compensatory extramedullary haematopoiesis primarily in the spleen but also observed in other organs such as the bone marrow and liver.  A NOAEL of 0.2 mg/kg bw/day was determined in rats after administration of hydroxylammonium sulphate via their drinking water and a LOAEL of 0.7 mg/kg in rabbits after sub acute dermal application of hydroxylammonium nitrate.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records
Reference
Endpoint:
chronic toxicity: oral
Remarks:
combined repeated dose and carcinogenicity
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
2001
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well reported study conducted to OECD guidelines, however there if no indication if the study was conducted to GLP
Qualifier:
according to
Guideline:
OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)
GLP compliance:
not specified
Limit test:
yes
Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
No data.
Route of administration:
oral: drinking water
Vehicle:
not specified
Details on oral exposure:
No data.
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
Not applicable.
Duration of treatment / exposure:
Satellite group: 12 months.
Main group: 24 months.
Frequency of treatment:
The test chemical was administered via the drinking water which was provided ad libitum.
Remarks:
Doses / Concentrations:
Satellite group (male): 0, 5, 20 80 ppm( reported as 0, 0.3, 1.1, 4.5 mg/kg bw/day)
Basis:
nominal in water
Remarks:
Doses / Concentrations:
Satellite group (female): 0, 5, 20 80 ppm (reported as 0, 0.4, 1.6, 6.2 mg/kg bw/day)
Basis:
nominal in water
Remarks:
Doses / Concentrations:
Main group (males): 0, 5, 20 80 ppm (reported as 0, 0.2, 1, 3.7 mg/kg bw/day)
Basis:
nominal in water
Remarks:
Doses / Concentrations:
Main group (females): 0, 5, 20 80 ppm (reported as 0, 0.4, 1.6, 6.2 mg/kg bw/day)
Basis:
nominal in water
No. of animals per sex per dose:
Satellite group: 10/sex/dose.
Main group: 50/sex/dose.
Control animals:
yes, concurrent no treatment
Details on study design:
A satellite study was conducted to define the haematotoxic potential of the test substance, hydroxylammonium sulphate. In the satellite animals, assays of blood parameters were performed every three months.
Positive control:
No positive control animals were used in the study.
Observations and examinations performed and frequency:
Food consumption, water consumption and body weight were determined once a week for the first 13 weeks. Thereafter water consumption and body weight was recorded monthly and food consumption determined every 3 months.

Animals were examined daily for signs of toxicity or mortality. Comprehensive clinical examinations and palpation of the animals were performed once a week.

Haematology was carried out on animals from the satellite group, after 3, 6, 9 and 12 months. Haematology was carried out in the animals from the main study group at 12, 18 and 24 months.
Sacrifice and pathology:
Complete necropsy and microscopy was performed on all animals at the study termination (12 and 24 months for satellite and main study animals, respectively).
Other examinations:
No data.
Statistics:
No data.
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:
no effects observed
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
20 ppm
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
80 ppm
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
80 ppm
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
20 ppm
Histopathological findings: neoplastic:
no effects observed
Details on results:
At 3, 6, 9, 12 and 24 months animals had dose-related haemolytic anemia which was more pronounced in male rats.


Satellite Group
At the highest dose animals had increased relative spleen weight, increased congested vessels (characterised by dilated blood filled vascular spaces) increased haemosiderin deposits and extramedullary haematopoiesis. Animals also had significant alterations to blood parameters: decreased red blood cell count, haemoglobin and haematocrit; increased mean corpuscular volume and haemoglobin, platelet count, reticulocyte count, heinz bodies and Howell- Jolly bodies.
At the second highest dose male animals also showed haemosiderin deposits in the spleen.

Main Group
At the highest dose animals showed similar toxicological effects in the spleen as the satellite animals. In addition animals also displayed an increased degree of diffuse haemosiderin storage in the liver and increased haematopoiesis in the bone marrow. At the highes dose, animals also had some change to blood cells; increased Howell Jowell bodies, anisocytosis, microcytosis and polychromasia.
At the second highest dose, female animals also showed increased haemosiderin storage in the spleen
Dose descriptor:
NOAEL
Remarks:
0.2-0.3 mg/kg bw/day
Based on:
dissolved
Sex:
male
Basis for effect level:
other: Based on haemotoxic effects
Remarks on result:
not measured/tested
Remarks:
Effect level not specified (migrated information)
Dose descriptor:
NOAEL
Remarks:
0.4 mg/kg bw/day
Based on:
dissolved
Sex:
male/female
Basis for effect level:
other: Based on haemotoxic effects
Remarks on result:
not measured/tested
Remarks:
Effect level not specified (migrated information)
Critical effects observed:
not specified
Conclusions:
Animals displayed dose-related haemolytic anemia along with compensatory effects characterised by extramedullary haematopoiesis in the spleen and the liver and increased red blood cell regeneration in the bone marrow. A NOAEL of 5 ppm (reported as 0.2 - 0.3 and 0.4 mg/kg bw/day for male and female rats, respectively) based on heamotlytic effects can be derived.
Executive summary:

In a chronic oral study in Wistar rats, hydroxylammonium sulphate was administered via their drinking water at concentrations of 0 (control), 5, 20 and 80 ppm for either 12 (satellite study) or 24 months (main study). The animals did not show any clinical signs of toxicity and food consumption, water consumption and body weight were not significantly different from control animals over the study period. Animals displayed dose-related haemolytic anemia along with compensatory effects characterised by extramedullary haematopoiesis in the spleen and the liver and increased red blood cell regeneration in the bone marrow. A NOAEL of 5 ppm (reported as 0.2 - 0.3 and 0.4 mg/kg bw/day for male and female rats, respectively) based on heamotlytic effects can be derived. This study is considered reliable and therefore hydroxylammonium sulphate is considered to be a haemotoxic agent in rats. Using this substance to read-across, it can be considered that hydroxylammonium nitrate is haemotoxic in rats.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
0.2 mg/kg bw/day
Study duration:
chronic
Species:
rat
Quality of whole database:
The studies located where mostly well reported and consistent with standardised guidelines.

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

Link to relevant study records
Reference
Endpoint:
short-term repeated dose toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1982
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was not conducted to GLP and did not follow a standardised guideline, however it is a well documented study and includes a well reported results section
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)
Deviations:
yes
Remarks:
less animals used than recommended by guideline,
GLP compliance:
not specified
Limit test:
no
Species:
rabbit
Strain:
New Zealand White
Sex:
male
Details on test animals and environmental conditions:
Male New Zealand White Rabbits ranged in weight from 2.2 -2.7 kg and were housed individually in stainless steel cages with food and water available ad libitum
Type of coverage:
other: none-occlusive
Vehicle:
not specified
Details on exposure:
The test solution was aplied with a microsyringe onto the clipped mid-lumbar region of the rabbit. Control animals were treated with water. Following each application, the area was covered by a non-occlusive patch to prevent the animal from licking the area. On the weekly shaving day, the compound was applied 4 hours after shaving.
Details on analytical verification of doses or concentrations:
No data.
Duration of treatment / exposure:
The test solution was applied 5 days a week for 3 weeks.
Frequency of treatment:
The test solution was applied 5 days a week for 3 weeks.
Remarks:
Doses / Concentrations:
0.7, 1.5, 2.9, 5.9, 11.7 mg/kg bw/day
Basis:
nominal per unit body weight
No. of animals per sex per dose:
5/male/dose
Control animals:
yes
Details on study design:
The doses applied were fractions of the acute dermal occluded LD50 (70 mg/kg).
The applied doses were: 0 (control), 0.7, 1.5, 2.9, 5.9 and 11.7 mg/kg.
Animals were weighed weekly and doses for that week were calculated from this weight.
Positive control:
No data
Observations and examinations performed and frequency:
Animals were inspected daily prior to treatment. Animals were weighed weekly to to determine the following weeks dose.
Sacrifice and pathology:
All animals were sacrificed at the end of the study period and necropsied.
Other examinations:
No data.
Statistics:
Results from each test group were compared with the control group. Results were compared statistically with a Mann-Whitney U-test. Results were considered stastically significant at 0.05.
Clinical signs:
no effects observed
Dermal irritation:
effects observed, treatment-related
Description (incidence and severity):
Dermal irritation was oberved at doses of 0.7 mg/kg and greater
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
There was a decrease in bodyweight in animals dosed with 11.7 mg/kg
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 examined
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
Changes in blood parameters were observed at doses of 2.9 mg/kg and higher
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
Description (incidence and severity):
At concentrations greater than 2.9 mg/kg, spleen weights were higher than control animals
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Splenic haematopoiesis was observed at doses of 2.9 mg/kg and higher
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Extramedullary haematopoiesis observed at doses of 2.9 mg/kg and higher
Histopathological findings: neoplastic:
no effects observed
Details on results:
Histopathology:
At the end of the study period, animals in all treatment groups (not controls) displayed a high incidence of dermatitis. The incidence and severity of ulcerative dermatitis was dose-dependent. Ulcerative dermatitis was characterised by marked necrosis and a loss of epidermis with acute and chronic inflammatory infiltrates extending from the base of the epithelia necrosis into the dermis. In some instances superficial crusting composed of necrotic cellular debis and kerating was observed.

Chronic dermatitis did not show a definite dose-response among treatment groups. Chronic dermatitis was characterised by acanthosis, hyperkeratisis and dermal infiltrates of predominantly mono-nuclear cells. Infiltrates were varied (focal to diffuse) and extended from the epidermis to underlying musculature.

Clinical chemistry and haematology:
After the first dose of hydroxylammonium nitrate, blood samples taken 24 hours after application from animals receiving the highest dose contained Heinz bodies. One week after the initiation of dosing, blood samples from animals receiving the top three doses of the chemical were observed to contain Heinz bodies. Anemia was observed in all treatment groups except the lowest and control animals. RBC count, haemoglobin concentration, haemtocrit were lower in these animals and the MCV higher.

No changes in clinical chemistry parameters were detected.

Organ weights and gross pathology:
At necropsy, the relative spleen weight was higher in animals administered the three highest doses (2.9 - 11.7 mg/kg ) compared to controls, these animals also displayed splenic haematopoiesis. The colour of spleens ranged from dark red to black corresponging with increasing dose.
Extramedullary haematopoiesis was also observed in the liver of animals administered the two highest doses of the test chemical. Animals administered the highest dose also displayed higher relative heart weights.
Dose descriptor:
LOAEL
Effect level:
0.7 mg/kg bw/day (nominal)
Basis for effect level:
other: Local effects
Dose descriptor:
NOAEL
Effect level:
0.7 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: systemic effects
Critical effects observed:
not specified
Conclusions:
Dermal aplication of hydroxylammonium nitrate to rabbits caused dose dependent dermatitis with increasing severity related to higher doses. At the three highest doses, animals displayed heamolytic anemia and the formation of Heinz bodies in red blood cells. A LOAEL of 0.7 mg/kg bw/day, based on dermatitis can be derived from this study.
Executive summary:

In an acute dermal toxicity study similar to OECD Guideline 410, New Zealand White rabbits, 0.7, 1.5, 2.9, 5.9 and 11.7 mg/hydroxylammonium nitrate/kg was applied dermally on the mid-lumbar region for 5 days/week for 3 weeks. Animals displayed dose dependent dermatitis with increasing severity related to higher doses. At the three highest doses, animals displayed haemolytic anemia and the formation of Heinz bodies in red blood cells. Animals from these dose groups also displayed extramedullary haematopoiesis. A LOAEL of 0.7 mg/kg based on dermatitis can be derived from this study for local effects and a NOAEL of 0.7 mg/kg bw/day for systemic effects. This study is considered to be reliable and therefore hydroxylammonium nitrate is considered to cause dermatitis, haemolytic anemia and extramedullary haematopoiesis after dermal application in rabbits.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEL
0.7
Study duration:
subacute
Species:
rabbit
Quality of whole database:
Only one study was located, it was considered to be well reported and consistent with standardised guidelines and is therefore considered reliable (with restrictions).

Repeated dose toxicity: dermal - local effects

Link to relevant study records
Reference
Endpoint:
short-term repeated dose toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1982
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was not conducted to GLP and did not follow a standardised guideline, however it is a well documented study and includes a well reported results section
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)
Deviations:
yes
Remarks:
less animals used than recommended by guideline,
GLP compliance:
not specified
Limit test:
no
Species:
rabbit
Strain:
New Zealand White
Sex:
male
Details on test animals and environmental conditions:
Male New Zealand White Rabbits ranged in weight from 2.2 -2.7 kg and were housed individually in stainless steel cages with food and water available ad libitum
Type of coverage:
other: none-occlusive
Vehicle:
not specified
Details on exposure:
The test solution was aplied with a microsyringe onto the clipped mid-lumbar region of the rabbit. Control animals were treated with water. Following each application, the area was covered by a non-occlusive patch to prevent the animal from licking the area. On the weekly shaving day, the compound was applied 4 hours after shaving.
Details on analytical verification of doses or concentrations:
No data.
Duration of treatment / exposure:
The test solution was applied 5 days a week for 3 weeks.
Frequency of treatment:
The test solution was applied 5 days a week for 3 weeks.
Remarks:
Doses / Concentrations:
0.7, 1.5, 2.9, 5.9, 11.7 mg/kg bw/day
Basis:
nominal per unit body weight
No. of animals per sex per dose:
5/male/dose
Control animals:
yes
Details on study design:
The doses applied were fractions of the acute dermal occluded LD50 (70 mg/kg).
The applied doses were: 0 (control), 0.7, 1.5, 2.9, 5.9 and 11.7 mg/kg.
Animals were weighed weekly and doses for that week were calculated from this weight.
Positive control:
No data
Observations and examinations performed and frequency:
Animals were inspected daily prior to treatment. Animals were weighed weekly to to determine the following weeks dose.
Sacrifice and pathology:
All animals were sacrificed at the end of the study period and necropsied.
Other examinations:
No data.
Statistics:
Results from each test group were compared with the control group. Results were compared statistically with a Mann-Whitney U-test. Results were considered stastically significant at 0.05.
Clinical signs:
no effects observed
Dermal irritation:
effects observed, treatment-related
Description (incidence and severity):
Dermal irritation was oberved at doses of 0.7 mg/kg and greater
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
There was a decrease in bodyweight in animals dosed with 11.7 mg/kg
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 examined
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
Changes in blood parameters were observed at doses of 2.9 mg/kg and higher
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
Description (incidence and severity):
At concentrations greater than 2.9 mg/kg, spleen weights were higher than control animals
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Splenic haematopoiesis was observed at doses of 2.9 mg/kg and higher
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Extramedullary haematopoiesis observed at doses of 2.9 mg/kg and higher
Histopathological findings: neoplastic:
no effects observed
Details on results:
Histopathology:
At the end of the study period, animals in all treatment groups (not controls) displayed a high incidence of dermatitis. The incidence and severity of ulcerative dermatitis was dose-dependent. Ulcerative dermatitis was characterised by marked necrosis and a loss of epidermis with acute and chronic inflammatory infiltrates extending from the base of the epithelia necrosis into the dermis. In some instances superficial crusting composed of necrotic cellular debis and kerating was observed.

Chronic dermatitis did not show a definite dose-response among treatment groups. Chronic dermatitis was characterised by acanthosis, hyperkeratisis and dermal infiltrates of predominantly mono-nuclear cells. Infiltrates were varied (focal to diffuse) and extended from the epidermis to underlying musculature.

Clinical chemistry and haematology:
After the first dose of hydroxylammonium nitrate, blood samples taken 24 hours after application from animals receiving the highest dose contained Heinz bodies. One week after the initiation of dosing, blood samples from animals receiving the top three doses of the chemical were observed to contain Heinz bodies. Anemia was observed in all treatment groups except the lowest and control animals. RBC count, haemoglobin concentration, haemtocrit were lower in these animals and the MCV higher.

No changes in clinical chemistry parameters were detected.

Organ weights and gross pathology:
At necropsy, the relative spleen weight was higher in animals administered the three highest doses (2.9 - 11.7 mg/kg ) compared to controls, these animals also displayed splenic haematopoiesis. The colour of spleens ranged from dark red to black corresponging with increasing dose.
Extramedullary haematopoiesis was also observed in the liver of animals administered the two highest doses of the test chemical. Animals administered the highest dose also displayed higher relative heart weights.
Dose descriptor:
LOAEL
Effect level:
0.7 mg/kg bw/day (nominal)
Basis for effect level:
other: Local effects
Dose descriptor:
NOAEL
Effect level:
0.7 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: systemic effects
Critical effects observed:
not specified
Conclusions:
Dermal aplication of hydroxylammonium nitrate to rabbits caused dose dependent dermatitis with increasing severity related to higher doses. At the three highest doses, animals displayed heamolytic anemia and the formation of Heinz bodies in red blood cells. A LOAEL of 0.7 mg/kg bw/day, based on dermatitis can be derived from this study.
Executive summary:

In an acute dermal toxicity study similar to OECD Guideline 410, New Zealand White rabbits, 0.7, 1.5, 2.9, 5.9 and 11.7 mg/hydroxylammonium nitrate/kg was applied dermally on the mid-lumbar region for 5 days/week for 3 weeks. Animals displayed dose dependent dermatitis with increasing severity related to higher doses. At the three highest doses, animals displayed haemolytic anemia and the formation of Heinz bodies in red blood cells. Animals from these dose groups also displayed extramedullary haematopoiesis. A LOAEL of 0.7 mg/kg based on dermatitis can be derived from this study for local effects and a NOAEL of 0.7 mg/kg bw/day for systemic effects. This study is considered to be reliable and therefore hydroxylammonium nitrate is considered to cause dermatitis, haemolytic anemia and extramedullary haematopoiesis after dermal application in rabbits.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LOAEL
0.7
Study duration:
subacute
Species:
rabbit
Quality of whole database:
Only one repeated dose dermal toxicity study was located. However the study was very well reported (including raw data) and consistent with standardised guidelines for repeated dose dermal toxicity studies.

Additional information

The studies located relating to the repeat oral toxicity of hydroxylammonium nitrate and associated analogues, gave consistent results indicating that the chemical causes methaemaglobinaemia and anaemia with compensatory extramedullary haematopoiesis. Two studies indicated that male rats may be more sensitive to toxic effects from the test chemical than female animals, this includes the key study.

No studies were located on the repeat inhalation toxicity of hydroxylammonium nitrate.

Only one study was located on the repeat dermal toxicity of hydroxylammonium nitrate. The systemic effects were consistent with toxic effects observed after repeat oral administration of the chemical indicating dermal absorption. Local dermal effects were consistent with effects observed after acute dermal application (single application).


Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
The study was well reported and also had the longest administration period and the lowest NOAEL and was therefore the most conservative toxicological endpoint for all the studies.

Justification for selection of repeated dose toxicity dermal - systemic effects endpoint:
Only one repeated dose dermal toxicity study was located. However the study was very well reported (including raw data) and consistent with standardised guidelines for repeated dose dermal toxicity studies.

Justification for selection of repeated dose toxicity dermal - local effects endpoint:
Only one repeated dose dermal toxicity study was located. However the study was very well reported (including raw data) and consistent with standardised guidelines for repeated dose dermal toxicity studies.

Repeated dose toxicity: via oral route - systemic effects (target organ) cardiovascular / hematological: hematopoiesis

Repeated dose toxicity: dermal - systemic effects (target organ) cardiovascular / hematological: hematopoiesis

Justification for classification or non-classification

Hydroxylammonium nitrate is classified as STOT Rep. Ex. 2