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Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
sub-chronic toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
June 1986 to September 1986
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1996

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
A standard Test Guideline was not specified in this study.
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
other: F344/N
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Simonsen Laboratories, Gilroy, CA, USA
- Age at study initiation: 7 weeks
- Weight at study initiation: 131-135 g (male), 106-112 g (females)
- Fasting period before study: not reported
- Housing: individually housed
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 19-20 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.1-27.6 deg C
- Humidity (%): 43-76%
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light): 12 hours light/ 12 hours dark

IN-LIFE DATES: June 1986 to September 1986

Administration / exposure

Route of administration:
inhalation
Type of inhalation exposure:
whole body
Vehicle:
other: distilled and deionized water
Remarks on MMAD:
MMAD / GSD: 1.8-3.1 um MMAD, GSD = 1.6-2.9
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Stainless steel multitiered whole exposure chambers (Hazleton, Aberdeen, MD, USA)
- Method of holding animals in test chamber: not reported
- Source and rate of air: High-efficiency particulate air filter (Flanders, Washington, DC)
- Method of conditioning air: not reported
- System of generating particulates/aerosols: The test compound was generated from aqueous solutions (62.1 g/L in distilled and deionized water) and atomized.  
- Temperature, humidity, pressure in air chamber: Temp. 17-28.2 deg. C; humidity 13-82%
- Air flow rate: The aerosol was mixed with additional dilution air to achieve the proper concentration and flow rate.
- Air change rate: not reported
- Method of particle size determination: cascade impactor
- Treatment of exhaust air: not reported

TEST ATMOSPHERE
- Brief description of analytical method used: aerosol concentrations determined gravimetrically
- Samples taken from breathing zone: yes

VEHICLE (if applicable)
- water
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
aerosol concentrations determined gravimetrically
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
5 days/week for 13 weeks
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/m³ air (analytical)
Dose / conc.:
0.12 mg/m³ air (analytical)
Remarks:
Equivalent to 0.027 mg Ni/m3
Dose / conc.:
0.25 mg/m³ air (analytical)
Remarks:
Equivalent to 0.056 mg Ni/m3
Dose / conc.:
0.5 mg/m³ air (analytical)
Remarks:
Equivalent to 0.11 mg Ni/m3
Dose / conc.:
1 mg/m³ air (analytical)
Remarks:
Equivalent to 0.22 mg Ni/m3
Dose / conc.:
2 mg/m³ air (analytical)
Remarks:
Equivalent to 0.44 mg Ni/m3
No. of animals per sex per dose:
10 males and 10 females per dose
Control animals:
yes, concurrent no treatment
Details on study design:
- Dose selection rationale: not reported
- Rationale for animal assignment (if not random): distributed randomely into groups of approximately equal initial mean body weights
Positive control:
none reported

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: on Day 5 and at the end of the study.

BODY WEIGHT: Yes
- Time schedule for examinations: on Day 5 and at the end of the study.

HAEMATOLOGY: Yes
- Hematology parameters measured: hematocrit, hemoglobin, erythrocytes, mean erythrocyte volume, mean erythrocyte hemoglobin concentration,  reticulocytes, total leukocytes, and differential and nucleated erythrocytes.
Sacrifice and pathology:
GROSS PATHOLOGY/HISTOPATHOLOGY:
Necropsy was performed on all animals.  The following organs were weighed at necropsy: brain, heart, right kidney, liver, lung, right testis, and  
thymus. Hematology parameters measured: hematocrit, hemoglobin, erythrocytes, mean erythrocyte volume, mean erythrocyte hemoglobin 
concentration, reticulocytes, total leukocytes, and differential and nucleated erythrocytes. Complete histopathology was performed on rats in the 
0 and 2 mg/m3 dose groups.  

Gross lesions and tissues examined included: adrenal gland, bone, brain, clitoral gland, epididymis or oviduct, esophagus, heart, large intestine 
(including cecum, colon, rectum), small intestine (including duodenum, jejunum, ileum), kidneys, larynx, liver, lung, lymph nodes, mammary gland, 
nose, ovary, pancreas, parathyroid gland, pituitary gland, pancreatic islets, preputial gland, prostate, salivary gland, seminal vesicle, skin, spleen, 
stomach, testis, thymus, thyroid gland, trachea, urinary bladder, and uterus.
Other examinations:
The following organs were examined from selected groups of rats: lung, nose, respiratory tract, and lymph nodes (bronchial and mediastinal).
Sperm samples were collected from male rats exposed to 0, 0.5, 1, and 2 mg/m2 for evaluation (sperm density, morphology, and motility).  
The right epididymis, right caudae, and right testis were weighed.  Vaginal samples were collected from all female rats exposed to 0, 0.5, 1, and 2  
mg/m3 for vaginal cytology evaluations (frequency of estrous stages and estrous cycle length). Additionally, tissue burden studies were 
conducted on 5 or 6 male and female rats exposed to 0, 0.12, 0.5, or 2 mg/m3.  Samples of lung and kidney tissues were collected and analyzed for 
nickel content.
Statistics:
The probability of survival was estimated by the product-limit procedure of Kaplan and Meier (1958).  Dose-related effects were analyzed using  
Cox's (1972) method for testing two groups for equality, and Tarone's (1975) life table test to identify dose-related trends.  Organ and body  
weight data were analyzed using the parametric multiple comparison procedures of Dunnett (1955) and Williams (1971, 1972).

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Description (incidence and severity):
See section "details on results"
Mortality:
no mortality observed
Description (incidence):
See section "details on results"
Body weight and weight changes:
no effects observed
Description (incidence and severity):
See section "details on results"
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):
See section "details on results"
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):
See section "details on results"
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
See section "details on results"
Histopathological findings: neoplastic:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY:
Survival (number of animals surviving/total number tested), by dose level tested:
0 mg/m3: 10/10 males, 10/10 females
0.12 mg/m3: 10/10 males, 10/10 females
0.25 mg/m3: 10/10 males, 10/10 females
0.5 mg/m3: 10/10 males, 10/10 females
1 mg/m3: 10/10 males, 10/10 females
2 mg/m3: 9/10 males, 10/10 females

No clinical findings were reported.

BODY WEIGHT AND WEIGHT GAIN
Final mean body weights and body weight gains of surviving mice were not significantly different from the control group.  

HAEMATOLOGY
significant treatment-related hematology changes reported:
-increased hemoglobin of males at 1 and 2 mg/m3
-increased erythrocytes of males at 1 and 2 mg/m3
-increased reticulocytes of males at all dose levels tested
-increased leukocytes of males at 0.5, 1, and 2 mg/m3
-increased segmented neutrophils of males at 0.25, 0.5, 1, and 2 mg/m3, and of females at 1 and 2 mg/m3
-increased lymphocytes of males at 1 and 2 mg/m3
-increased monocytes of males at 2 mg/m3 -decreased mean cell volume of females at 2 mg/m3
-increased mean cell hemoglobin concentration of females at all dose levels tested.

ORGAN WEIGHTS:
Significant organ weight changes reported:
-increased relative brain weight of males at 2 mg/m3
-decreased absolute liver weight of males and females at 2 mg/m3
-increased absolute lung weight of males and females at 0.25, 0.5, 1, and 2 mg/m3
-increased relative lung weight of males at 0.5, 1, and 2 mg/m3 and of females at 0.25, 0.5, 1, and 2 mg/m3.

HISTOPATHOLOGY
There was an exposure-related increase in histopathologic lesions (alveolar macrophage, hyperplasia) present in the lungs of male and female rats; significant all dose levels tested.
Significant incidences of non-neoplastic lesions reported:
- Interstitial infiltrate of males at 1 and 2 mg/m3, and of females at 0.5, 1, and 2 mg/m3
- chronic active inflammation of males at 1 and 2 mg/m3, and of females at 0.5, 1, and 2 mg/m3
- hyperplasia of bronchial lymph nodes of males and females at 1 and 2 mg/m3
- atrophy of olfactory epithelium of males and females at 1 and 2 mg/m3.

OTHER FINDINGS
No significant differences in sperm morphology or vaginal cytology were found between exposed rats and control rats.
The nickel concentrations in the lungs of 0.5 or 2 mg/m3 rats were significantly higher than the control animals at 4, 9, and 13 weeks for males at 13 weeks for females.  The concentrations of nickel in the kidney of male and female rats exposed to 0.5 or 2 mg/m3 were similar to levels found in control animals.

Chronic lung inflammation was the most serious adverse effect detected.  Females were more sensitive than males with a LOAEC of 0.11 mg Ni/m3 (0.5  mg nickel sulfate hexahydate/m3) and a NOAEC of 0.056 mg Ni/m3 (0.25 mg nickel sulfate hexahydate/m3 ).

Effect levels

open allclose all
Dose descriptor:
NOAEL
Effect level:
0.25 other: mg Ni/m² (as Ni sulphate hexahydrate)
Based on:
element
Sex:
male/female
Basis for effect level:
other: Chronic active lung inflammation
Dose descriptor:
LOAEL
Effect level:
0.5 other: mg Ni/m² (as Ni sulphate hexahydrate)
Based on:
element
Sex:
male/female
Basis for effect level:
other: Chronic active lung inflammation

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
The NOAEC/LOAEC for inflammation which is regarded as a clear adverse effect is 0.056/0.11 mg Ni/m3 (0.25/0.5 mg NiSO4.6H2O /m3).
Executive summary:

STUDY RATED BY AN INDEPENDENT REVIEWER.

ROBUST SUMMARY DEVELOPED BY AN INDEPENDENT REVIEWER.

Robust Summary for NTP (1996)

Male and female F344/N rats were obtained from Simonsen Laboratories, Gilroy, CA, USA.  Groups of 20 rats (10 males + 10 females) were  

individually housed and provided food and water ad libitum, except during exposure.  7-week old mice were exposed to the test substance via whole  

body inhalation chambers.  Chambers were maintained at a temperature of 19.1-27.6 deg. C, a relative humidity of 43-76%, and a 12-h light/dark photo cycle.

The test compound was generated from aqueous solutions (62.1 g/L in distilled and deionized water) and atomized.  The aerosol was mixed with  

additional dilution air to achieve the proper concentration and flow rate.

Nickel sulfate hexahydrate concentrations tested were: 0, 0.12, 0.25, 0.5, 1 or 2 mg/m3 (equivalent to 0, 0.027, 0.056, 0.11, 0.22, or 0.44 mg Ni/m3 ).

Animals were observed twice daily.  Body weight and clinical observations were conducted at the start of the study, weekly during the study, and at  

the end of the study period.

Necropsy was performed on all animals.  The following organs were weighed at necropsy: brain, heart, right kidney, liver, lung, right testis, and thymus.

Hematology parameters measured: hematocrit, hemoglobin, erythrocytes, mean erythrocyte volume, mean erythrocyte hemoglobin concentration,  

reticulocytes, total leukocytes, and differential and nucleated erythrocytes.

Complete histopathology was performed on rats in the 0 and 2 mg/m3 dose groups.  Gross lesions and tissues examined included: adrenal gland,  

bone, brain, clitoral gland, epididymis or oviduct, esophagus, heart, large intestine (including cecum, colon, rectum), small intestine  

(including duodenum, jejunum, ileum), kidneys, larynx, liver, lung, lymph nodes, mammary gland, nose, ovary, pancreas, parathyroid gland, pituitary  

gland, pancreatic islets, preputial gland, prostate, salivary gland, seminal vesicle, skin, spleen, stomach, testis, thymus, thyroid gland,  trachea, urinary bladder, 

and uterus.

The following organs were examined from selected groups of mice: lung, nose, respiratory tract, and lymph nodes (bronchial and mediastinal).

Sperm samples were collected from male rats exposed to 0, 0.5, 1, and 2 mg/m2 for evaluation (sperm density, morphology, and motility).  The  

right epididymis, right caudae, and right testis were weighed.  Vaginal samples were collected from all female rats exposed to 0, 0.5, 1, and 2  

mg/m3 for vaginal cytology evaluations (frequency of estrous stages and estrous cycle length).

Additionally, tissue burden studies were conducted on 5 or 6 male and female rats exposed to 0, 0.12, 0.5, or 2 mg/m3.  Samples of lung and  

kidney tissues were collected and analyzed for nickel content.

The probability of survival was estimated by the product-limit procedure of Kaplan and Meier (1958).  Dose-related effects were analyzed using  

Cox's (1972) method for testing two groups for equality, and Tarone's (1975) life table test to identify dose-related trends.  Organ and body  

weight data were analyzed using the parametric multiple comparison procedures of Dunnett (1955) and Williams (1971, 1972).

Survival (number of animals surviving/total number tested), by dose level tested:
0 mg/m3: 10/10 males, 10/10 females
0.12 mg/m3: 10/10 males, 10/10 females
0.25 mg/m3: 10/10 males, 10/10 females
0.5 mg/m3: 10/10 males, 10/10 females
1 mg/m3: 10/10 males, 10/10 females
2 mg/m3: 9/10 males, 10/10 females

Final mean body weights and body weight gains of surviving mice were not significantly different from the control group.  No clinical findings were reported.

No significant differences in sperm morphology or vaginal cytology were found between exposed rats and control rats.

Significant organ weight changes reported:
-increased relative brain weight of males at 2 mg/m3
-decreased absolute liver weight of males and females at 2 mg/m3
-increased absolute lung weight of males and females at 0.25, 0.5, 1, and 2 mg/m3
-increased relative lung weight of males at 0.5, 1, and 2 mg/m3 and of females at 0.25, 0.5, 1, and 2 mg/m3.

Significant treatment-related hematology changes reported:
-increased hemoglobin of males at 1 and 2 mg/m3
-increased erythrocytes of males at 1 and 2 mg/m3
-increased reticulocytes of males at all dose levels tested
-increased leukocytes of males at 0.5, 1, and 2 mg/m3
-increased segmented neutrophils of males at 0.25, 0.5, 1, and 2 mg/m3, and of females at 1 and 2 mg/m3
-increased lymphocytes of males at 1 and 2 mg/m3
-increased monocytes of males at 2 mg/m3
-decreased mean cell volume of females at 2 mg/m3
-increased mean cell hemoglobin concentration of females at all dose levels tested.

There was an exposure-related increase in histopathologic lesions (alveolar macrophage, hyperplasia) present in the lungs of male and  

female rats; significant all dose levels tested.  Significant incidences of non-neoplastic lesions reported:
-Interstitial infiltrate of males at 1 and 2 mg/m3, and of females at 0.5, 1, and 2 mg/m3
-chronic active inflammation of males at 1 and 2 mg/m3, and of females at 0.5, 1, and 2 mg/m3
-hyperplasia of bronchial lymph nodes of males and females at 1 and 2 mg/m3

-atrophy of olfactory epithelium of males and females at 1 and 2 mg/m3.

The nickel concentrations in the lungs of 0.5 or 2 mg/m3 rats were significantly higher than the control animals at 4, 9, and 13 weeks for  

males at 13 weeks for females.  The concentrations of nickel in the kidney of male and female rats exposed to 0.5 or 2 mg/m3 were similar to  

levels found in control animals.

Chronic lung inflammation was the most serious adverse effect detected.  Females were more sensitive than males with a LOAEC of 0.11 mg Ni/m3 (0.5  

mg nickel sulfate hexahydate/m3) and a NOAEC of 0.056 mg Ni/m3 (0.25 mg nickel sulfate hexahydate/m3 ).