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Toxicological information

Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
sub-chronic toxicity: inhalation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
June 1986 to September 1986
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: 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
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Nickel Sulfate Hexahydrate, 10101-97-0
- Molecular formula (if other than submission substance): not different than submission substance
- Molecular weight (if other than submission substance): not different than submission substance
- Smiles notation (if other than submission substance): not different than submission substance
- InChl (if other than submission substance): not different than submission substance
- Structural formula attached as image file (if other than submission substance): not different than submission substance
- Physical state: blue-green crystalline powder
- Purity: >98%
- Lot #: M06288
- Impurities: Spark source mass spectrometry indicated the major inorganic impurities were silicon (470 ppm), magnesium (120 ppm), and cobalt (approximately 1,500 ppm).
- Other details not reported or not applicable

Test animals

Species:
mouse
Strain:
B6C3F1
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Simonsen Laboratories, Gilroy, CA, USA
- Age at study initiation: 7-week old mice
- Weight at study initiation: 23-25 g (males), 17-19 g (females)
- Fasting period before study: not reported
- Housing: individually housed
- Diet (e.g. ad libitum): ad libitum, except during exposure
- Water (e.g. ad libitum): ad libitum, except during exposure
- Acclimation period: 11 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-h light/dark photo cycle

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 / concentrations
Remarks:
Doses / Concentrations:
0, 0.12, 0.25, 0.50, 1, or 2 mg/m3 (equivalent to 0, 0.027, 0.056, 0.11, 0.22, or 0.44 mg Ni/m3)
Basis:
analytical conc.
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.

-Other evaluations not reported
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. The following organs were examined from selected groups of mice: lung, nose, respiratory tract, and lymph nodes (bronchial and mediastinal).

Complete histopathology was performed on mice in the 0 and 2 mg/m3 dose groups.  Gross lesions and tissues examined included: adrenal gland,   bone, brain, epididymis or oviduct, gallbladder, 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, prostate, salivary gland, seminal vesicle, skin, spleen, stomach, testis, thymus, thyroid gland, trachea, urinary bladder, and uterus.
Other examinations:
Sperm samples were collected from male mice 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 mice 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 mice 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
Mortality:
no mortality observed
Body weight and weight changes:
not specified
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
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
Gross pathological findings:
not specified
Histopathological findings: non-neoplastic:
effects observed, treatment-related
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: 6/10 males, 7/10 females
0.12 mg/m3: 8/9 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: 10/10 males, 10/10 females

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:
There were no significant hematology changes in male mice exposed to the  test substance.  In female mice, the following hematology changes were  significant: -increased hemoglobin concentration at 1 and 2 mg/m3 -increased leukocytes at 1 and 2 mg/m3 -increased segmented neutrophils at 0.5, 1, and 2 mg/m3 -increased lymphocytes at 1 and 2 mg/m3 -increased nucleated erythrocytes at 2 mg/m3.

ORGAN WEIGHTS:
Absolute and relative lung weights were significantly increased in male  mice at 1 and 2 mg/m3 and in female mice at 2 mg/m3.  There were no other significant differences in relative or absolute organ weights.

HISTOPATHOLOGY:
There was an exposure-related increase in histopathologic lesions (alveolar macrophage, hyperplasia) present in the lungs of male and  female mice; significant at 0.5, 1, and 2 mg/m3.  Incidences of interstitial infiltrate, chronic active inflammation, and atrophy of the olfactory epithelium were significant in male and female mice exposed to the test substance at 2 mg/m3.  In female mice, hyperplasia of the bronchial lymph node and fibrosis of the lung was significant at 2 mg/m3. No treatment related histopathological changes were found in male and female mice exposed to 0.12 or 0.25 mg/m3.

OTHER FINDINGS:
The nickel concentration in the lungs of 2 mg/m3 female mice was significantly higher than the control animals.
No significant differences in sperm morphology or vaginal cytology was found between exposed mice and control mice.

Effect levels

open allclose all
Dose descriptor:
NOAEL
Effect level:
0.22 other: mg Ni/m3
Sex:
male/female
Basis for effect level:
other: inflammation, fibrosis and atrophy
Dose descriptor:
LOAEL
Effect level:
0.44 other: mg Ni/m3
Sex:
male/female
Basis for effect level:
other: inflammation, fibrosis and atrophy

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
The NOAEC/LOAEC for inflammation, fibrosis and atrophy which are regarded as clear adverse effects is 0.22/0.44 mg Ni/m3 (1 and 2 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 B6C3F1 mice were obtained from Simonsen Laboratories, Gilroy, CA, USA.  Groups of 20 mice (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 mice in the 0 and 2 mg/m3 dose groups.  Gross lesions and tissues examined included: adrenal gland,  

bone, brain, epididymis or oviduct, gallbladder, 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,  

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 mice 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 mice 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 mice 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: 6/10 males, 7/10 females
0.12 mg/m3: 8/9 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: 10/10 males, 10/10 females

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

No significant differences in sperm morphology or vaginal cytology was  found between exposed mice and control mice.

Absolute and relative lung weights were significantly increased in male  mice at 1 and 2 mg/m3 and in female mice at 2 mg/m3.  There were no other significant 

differences in relative or absolute organ weights.

There were no significant hematology changes in male mice exposed to the  test substance.  In female mice, the following hematology changes were significant:
-increased hemoglobin concentration at 1 and 2 mg/m3
-increased leukocytes at 1 and 2 mg/m3
-increased segmented neutrophils at 0.5, 1, and 2 mg/m3
-increased lymphocytes at 1 and 2 mg/m3
-increased nucleated erythrocytes at 2 mg/m3

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

female mice; significant at 0.5, 1, and 2 mg/m3.  Incidences of interstitial infiltrate, chronic active inflammation, and atrophy of the  

olfactory epithelium were significant in male and female mice exposed to the test substance at 2 mg/m3.  In female mice, hyperplasia of the  

bronchial lymph node and fibrosis of the lung was significant at 2 mg/m3.

No treatment related histopathological changes were found in male and female mice exposed to 0.12 or 0.25 mg/m3.

The nickel concentration in the lungs of 2 mg/m3 female mice was significantly higher than the control animals.