Nickel(2+) propionate

Carcinogenicity

Description of key information

ORAL: read-across to nickel sulfate hexahydrate (CAS 10101-97-0): OECD 451, negative

INHALATION: read-across to nickel sulfate hexahydrate (CAS 10101-97-0): negative, classification based on read across to nickel diacetate (CAS 373-02-4), nickel sulphate (CAS 7786-81-4), nickel chloride hexahydrate (CAS 7791-20-0) (category 1A, H350)

Key value for chemical safety assessment

Carcinogenicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

carcinogenicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

Please refer to IUCLID section 13 for justification of read-across.

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Effect level:

10 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: overall effects

Key result

Critical effects observed:

no

Reference 2

Endpoint:

carcinogenicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.4200 (Carcinogenicity)

Qualifier:

according to guideline

Guideline:

OECD Guideline 451 (Carcinogenicity Studies)

GLP compliance:

yes

Species:

rat

Strain:

other: Fischer CDF(344)/CrlBR

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc., Raleigh, North Carolina
- Age at study initiation: 6 weeks
- Weight at study initiation: 118 to 147 g for males and 93 to 112 g for females
- Housing: housed individually in suspended stainless steel cages that were rotated in a regular fashion
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: acclimated to the laboratory conditions prior to in-life initiation
- Other: The results of the pretest health screen (gross necropsy and serological analyses) conducted prior to in-life initiation indicated that the population of animals was suitable for study use. Serological analyses of blood samples fromfive male and five female sentinel animals conducted by BioReliance Corporation, Rockville, Maryland, during weeks 25, 51, 77 and 103 did not reveal the presence of any viral infections that would negatively impact the results of this study.


ENVIRONMENTAL CONDITIONS
- Temperature: 70 to 76 °F
- Humidity (%): 29 to 73 %
- Air changes (per hr): 10 to 15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12-h light/12-h dark cycle

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
A specified amount of the test article and vehicle was mixed weekly. The mixtures were stirred continuously throughout each exposure period. The appearance of each test article preparation was determined and documented as a clear colorless solution for groups 2 and 3 (10 and 30 mg/kg bw/day) and a clear pale blue solution for group 4 (50 mg/kg bw/day).

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses were conducted by KAR Laboratories, Inc. (Kalamazoo, Michigan) prior to study initiation, during week 51, and following study completion to confirm the stability and purity of the test substance. Reverse osmosis deionized tap water was used for administration to control animals and in the preparation of the test article mixtures. Analytical concentration verification analyses conducted throughout the study demonstrated that the exposure solutions were stable and properly prepared. All analyses were within ±10% of the nominal concentration.

Duration of treatment / exposure:

104 weeks

Frequency of treatment:

daily

Dose / conc.:

0 mg/kg bw/day

Remarks:

referred to as group 1

Dose / conc.:

10 mg/kg bw/day (nominal)

Remarks:

referred to as group 2

Dose / conc.:

30 mg/kg bw/day (nominal)

Remarks:

referred to as group 3

Dose / conc.:

50 mg/kg bw/day (nominal)

Remarks:

referred to as group 4

No. of animals per sex per dose:

60

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale:
Exposures for the 90-day range finding study were selected based on previous gavage studies of nickel sulfate hexahydrate in rats. Two reproductive studies using Sprague–Dawley rats indicated that graded daily exposures from 5 to 125 mg/kg bw/day for one and two generations (>90 days in two generation study) resulted in few overt signs of toxicity. These studies also demonstrated the onset of lethality from administration of nickel sulfate hexahydrate at 150 mg/kg bw/d.
The 90-day range-finding study of nickel sulfate hexahydrate administered by gavage was conducted using exposures of 0, 50, 75, 100, 125, and 150 mg/kg bw/d. Based on the data from the 90-day range-finding study, exposure levels of 10, 30 and 50 mg/kg bw/day were selected for the 2 year oral gavage carcinogenicity study.

-Rationale for animal assignment: Sixty female and sixty male animals were assigned to each exposure group using a computer randomization program.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: General health/mortality/moribundity checks were performed twice daily.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Detailed clinical observations were performed weekly and on the day of scheduled euthanasia (weeks 104–105). Beginning on week 25, detailed clinical observations included a palpable mass examination (including the occurrence, size, location and description of any palpable masses) followed by persistence or disappearance of these masses being documented at the next weekly clinical observation.

BODY WEIGHT: Yes
- Time schedule for examinations: Individual body weights were recorded prior to randomization (day −3), on day 0 (i.e., the start of exposure), weekly during the first 13 weeks, once every 4 weeks thereafter and during week 103.

FOOD CONSUMPTION AND COMPOUND INTAKE
- Individual food consumption (grams/animal/day) was recorded on day 0, weekly during the first 13 weeks and once every 4 weeks thereafter, with the final food consumption measurement during week 103.

HAEMATOLOGY: Yes
- Selected hematological parameters were measured in blood samples collected from 10 animals/sex/group during week 54 (via tail vein) and prior to scheduled euthanasia during week 104/105 (via orbital plexus). Hematology and clinical chemistry parameters were measured according to the OECD 451 protocol.

Sacrifice and pathology:

GROSS PATHOLOGY/HISTOPATHOLOGY:
All animals were subjected to a complete gross necropsy examination at the time of death or euthanasia. Tissues collected at necropsy from all animals were processed for histopathological evaluation. Slides were prepared by Histo Techniques (Powell, Ohio) and Charles River Laboratories-Pathology Associates (Frederick, Maryland) and were examined microscopically by a Charles River Laboratories board-certified veterinary pathologist.

Other examinations:

Near the end of the study (week 103), additional biological sampling was performed to provide data on nickel in urine, feces and blood. Immediately following exposure on 1 day during week 103, five females and five males from each exposure group were placed in urine collection cages equipped with fecal collection screens, and an ice bath for cooling collected urine samples. Blood was collected from the orbital plexus of each animal approximately 30 min and 24 h post-exposure and sent to WIL Research Laboratories, Inc. (Ashland, Ohio) for analysis of blood nickel concentration. Urine and fecal samples were collected from each cage approximately 24 h post-exposure and sent to KAR Laboratories, Inc. for urine and fecal analysis of nickel concentrations. Urine was analyzed also for creatinine and albumin concentrations. Other standard hematology and clinical chemistry parameters for blood as well as other standard urinalysis parameters for urine were measured by Charles River Laboratories.

Statistics:

In-life data: The data were initially tested for normality using Levene's test for equality of variance followed by the Shapiro–Wilks test for normality.
A p≤0.001 level of significance was required for either test to reject the assumptions. If both assumptions were fulfilled, a singlefactor ANOVA was applied, with animal grouping as the factor, utilizing a p≤0.05 level of significance. If the parametric ANOVA was significant at p≤0.05, Dunnett's test was used to identify statistically significant differences between the control group and each nickel sulfate-treated group at the 0.05, 0.01 and 0.001 levels of significance. If either of the parametric assumptions was not satisfied, then the Kruskal–Wallis nonparametric ANOVA procedure was used to evaluate intergroup differences (p≤0.05). The Dunn's multiple comparison test was applied if this ANOVA was significant, again utilizing significance levels of p≤0.05, 0.01 and 0.001.


Survival Data: Kaplan–Meier estimates of group survival rates were calculated, by sex, and shown graphically. A log-rank dose response trend test of survival rates was performed utilizing dose coefficients. In addition, a log-rank test for survival was used to make pairwise comparisons of each treated group with the control group. Both the trend test and pairwise comparisons were conducted at the 0.05 significance level.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

The type and incidence of clinical signs observed in the treated groups were generally comparable to those observed in the control group.

Mortality:

mortality observed, treatment-related

Description (incidence):

There was a higher rate of mortality in groups 2–4 treated males and females during the first 24 weeks of this study which appeared to b treatment-related. Nickel induced pulmonary toxicity secondary to aspiration of the nickel sulfate solution was a potential cause. A later exposure time after week 24 (since rats are nocturnal feeders and 10 mL/kg exposure volume early in the morning to animals with relatively full stomachs may have produced sufficient gastric back pressure to force a portion of the administered dose to the opening of the trachea where it was aspirated) was effective in increasing survival, possibly by reducing aspiration of the test substance.
Mortality during week 24-48: only one death in nickel sulfate-treated group 3.
For the entire 104 weeks period there was no apparent treatment-related effect on mortality in males. In females, there was an increasing exposure–response trend in mortality relative to the controls (p<0.008).

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weights decreased in a exposure-dependent manner, with significantly decreased body weights observed in the two highest exposure groups for males and females (groups 3–4) Reductions in weight gain relative to controls at study week 103 reached the level of biological significance (i.e., >10% decrease) in the group 3 and 4 males and the group 4 females. This significant weight reduction indicates that the Maximum Tolerated Dose was reached in this study for both males and females.

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

A few statistically significant differences in the hematology data were observed in the treated males and females. For example, there were increases in red blood cells, hematocrit and/or hemoglobin in some of the animals in the 30 and 50 mg/kg bw/day groups. These changes may be associated with dehydration or could be related to nickel effects on gene expression of erytropoetin (HIF-inducible factor). However, none of these differences was suggestive of a hyperplastic (i.e., leukemia) response and none of these changes was considered toxicologically meaningful since they were small and did not follow a consistent exposure-related pattern.

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Numerous gross necropsy findings were observed for animals in the control and nickel sulfate-treated groups but the type and incidence of these findings observed for the treated animals were comparable to those observed in the control group, and were consistent with findings commonly seen in aging rats in a longterm study. None of the neoplastic or non-neoplastic microscopic findings was considered to be related to the experimental exposures. The non-neoplastic findings were either considered to be secondary to toxicity or incidental background occurrences rather than a direct effect of nickel sulfate. Some examples of non-neoplastic findings in the 50mg/kg bw/day males include: increases in yperplasia of pars distalis of the pituitary gland, bronchial inflammation, lymphoid follicle atrophy of spleen, mandibular lymph node cystic degeneration, histiocytes infiltration of mesenteric lymph nodes, hyperkeratosis of the tail, eye mineralization and vacuolization of adrenal cortex. In the stomach, there was an increase in the erosion of glands, but a decrease in epithelial erosion. Decreases in atrophy of pancreatic acinus, mineralization of aorta, hyperplasia of thymus and presence of renal tubule pigment were also observed. Most of these effects were not observed in the 50 mg/kg bw/day female animals with the exception of the increases in bronchial inflammation, spleen and mandibular lymph node effects and the decreases seen for kidney pigmentation, eye effects and erosion of stomach glands. The increased bronchial inflammation seen in 50 mg/kg bw/day male and female rats was considered to be the indirect result of minor aspirations during gavage exposure.

Histopathological findings: neoplastic:

no effects observed

Details on results:

The pathology report, pathology peer-review and the pathology working group concurred that nickel sulfate hexahydrate did not cause any carcinogenic effects in this study. Analysis of the tumor data revealed only one statistically significant (p<0.001) increase in tumors corresponding to keratoacanthoma (tail) in the group 2 males. However, this finding is of questionable toxicologic significance since there was no exposure–response relationship, the incidence rate in the group 2 males (15%) was only slightly higher than the upper end of Haseman's historical control incidence for this tumor type (0–14%) and the incidence rate in the remaining control and treated groups (0–7%) was within the range of the CRL-Ohio historical incidence (0–2%) and the Haseman historical incidence (0–14%). No other tumor finding in this study was statistically significant.
No notable differences were observed between controls and treated animals for the hematology, biochemistry and urinalysis parameters measured during the toxicokinetic satellite study.
Nickel levels in feces increased in an exposure-dependent manner in the treated males and females. The relatively high fecal levels compared to the blood and urinary nickel levels demonstrated that the majority of the nickel the animals were exposed to was not systemically absorbed, but was excreted in the feces.

Relevance of carcinogenic effects / potential:

The treatment did not produce an exposure-related increase in tumorigenicity. Only one tumor type in one exposure group was statistically different from the study controls (keratoacanthoma in the 10 mg/kg/day males), but no exposure–response relationship was observed and this is a common tumor type. Therefore, results of this study indicate that nickel sulfate hexahydrate does not cause
carcinogenicity to rats when administered orally.

Dose descriptor:

LOAEL

Effect level:

6.7 other: Ni/kg bw/d

Sex:

male/female

Basis for effect level:

body weight and weight gain

Dose descriptor:

LOAEL

Effect level:

30 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

Dose descriptor:

NOAEL

Effect level:

2.2 other: Ni/kg bw/d

Sex:

male/female

Basis for effect level:

other: overall effects

Key result

Dose descriptor:

NOAEL

Effect level:

10 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: overall effects

Key result

Critical effects observed:

no

Conclusions:

The NOAEL of the test substance was determined to be 10 mg/kg bw/d. The test substance does not cause carcinogenicity to rats when administered orally.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

10 mg/kg bw/day

Study duration:

chronic

Species:

rat

Quality of whole database:

GLP and Guideline study

Carcinogenicity: via inhalation route

Link to relevant study records

Reference

Reference 1

Endpoint:

carcinogenicity: inhalation

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

May 1988 to May 1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

other: reference to same study, different species (mouse)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)

GLP compliance:

yes

Species:

rat

Strain:

other: F344/N

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Taconic Farms, Germantown, NY, USA.
- Age at study initiation: 6-week old
- Weight at study initiation: ~108-133 g
- Fasting period before study: not reported
- Housing: individually housed
- Diet: ad libitum, except during exposure
- Water: ad libitum, except during exposure

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17.2-29.6°C
- Humidity (%): 8-99%
- Air changes (per hr): 9-21/hour
- Photoperiod (hrs dark / hrs light): 12-h light/dark photo cycle

IN-LIFE DATES: June 1988 to June 1990

Route of administration:

inhalation: aerosol

Type of inhalation exposure (if applicable):

whole body

Vehicle:

other: distilled and deionized water

Remarks on MMAD:

MMAD / GSD: MMAD =2.08-2.52 µm

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Stainless steel multitiered whole exposure chambers (Hazleton, Aberdeen, MD, USA)
- Source and rate of air: High-efficiency particulate air filter (Flanders, Washington, DC)
- System of generating particulates/aerosols: Aerosols were generated by nebulization of test substance solutions (62.1 g/L in distilled and deionized water)
- Temperature, humidity, pressure in air chamber: Temp. 17.2-29.6 deg. C; humidity 8-99%
- Air flow rate: The aerosol was mixed with additional dilution air to achieve the proper concentration and flow rate.
- Method of particle size determination: Aerosol concentration was determined by taking three 2-h filter samples throughout the exposure day.
Real-time determination of aerosol concentration was made using real time aerosol monitor - model S units. Aerosol size was determined using cascade impactors. (The range of mass median aerodynamic diameters and GSD obtained throughout the study were 2.2-2.5 um and GSD=2.2)


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

VEHICLE: water

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Aerosol concentration was determined by taking three 2-h filter samples throughout the exposure day. Real-time determination of aerosol concentration was made using real time aerosol monitor - model S units. Aerosol size was determined using cascade impactors.

Duration of treatment / exposure:

6 h / d

Frequency of treatment:

5 days per week for a period of 2 years

Dose / conc.:

0 mg/m³ air (nominal)

Dose / conc.:

0.125 mg/m³ air (nominal)

Dose / conc.:

0.25 mg/m³ air (nominal)

Dose / conc.:

0.5 mg/m³ air (nominal)

No. of animals per sex per dose:

Groups of 63 to 65 male and 63 to 64 female rats

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale: based on previous 13-week study

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Animals were observed twice daily.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: conducted at the start of the study, weekly for 13 weeks, monthly during the remainder of the study, and at the end of the study period.

BODY WEIGHT: Yes
- Time schedule: conducted at the start of the study, weekly for 13 weeks, monthly during the remainder of the study, and at the end of the study period.

HAEMATOLOGY: Yes
- Blood was collected from the retroorbital sinus of as many as five male and five female mice at the 15-month interim evaluation.
- Hematology: hematocrit, hemoglobin, erythrocytes, mean erythrocyte volume, mean erythrocyte hemoglobin, mean erythrocyte hemoglobin concentration, reticulocytes, total leukocytes and differential, and nucleated erythrocytes.

Sacrifice and pathology:

GROSS PATHOLOGY/HISTOPATHOLOGY: Yes
Necropsy was performed on all animals.
The following organs were weighed at 7- and 15-months: brain, right kidney, liver, lung, spleen, and thymus.

Complete histopathology was performed on all mice. Gross lesions and tissues examined included: adrenal gland, bone, brain, clitoral gland, epididymis or oviduct, esophagus, heart, gallbladder, 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, preputial gland, prostate, salivary gland, seminal vesicle, skin, spleen, stomach, testis, thymus, thyroid gland, trachea, urinary bladder, and uterus.

Other examinations:

Ni levels in lung tissues were analyzed

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).

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The final mean body weights compared to the control group per 0.125 mg/m3, 0.25 mg/m3 and 0.5 mg/m3 exposure groups were 99 %, 101 % and 98 %, respectively for the male rats and 97 %, 97 % and 94 % for the females, respectively.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological 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):

Lung weights in exposed animals were greater than controls, this was considered to be related to inflammatory lung reactions that occurred in response to test substance exposure. At 15 months, the lung weights of in the high exposure group was 33-41 % more compared to the control.

Gross pathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

A spectrum of exposure-related nonneoplastic respiratory tract lesions seen after exposure included focal alveolar/bronchiolar hyperplasia, inflammation, and/or fibrosis of the lung and lymphoid hyperplasia of the lung-associated lymph nodes. Atrophy of the olfactory epithelium was also seen after exposure.

Histopathological findings: neoplastic:

no effects observed

Details on results:

ORGAN WEIGHTS:
Significant organ weight changes reported:
-increased relative lung weights of 0.25 and 0.5 mg/m3 males at 7-month evaluation.
-increased relative and absolute lung weights of 0.5 mg/m3 females at 7-month evaluation.
-increased relative and absolute lung weights of 0.5 mg/m3 males and females at 15-month evaluation.

HAEMATOLOGY:
There were no substance-related hematology differences or clinical findings reported. Lung Ni levels were significantly higher in Ni-exposed rats relative to the control animals. Lung Ni levels increased with increasing Ni exposure levels.

HISTOPATHOLOGY: NON-NEOPLASTIC
Significantly-increased incidences of non-neoplastic lung lesions reported for 2-year study:
-chronic active lung inflammation of 0.25 and 0.5 mg/m3 rats.
-macrophage hyperplasia of 0.25 and 0.5 mg/m3 rats.
-alveolar proteinosis of 0.25 and 0.5 mg/m3 rats.
-fibrosis of 0.25 and 0.5 mg/mg3 rats.

Result (carcinogenicity): negative

Dose descriptor:

LOAEL

Effect level:

0.25 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: chronic active lung inflammation

Remarks on result:

other: equivalent to 0.056 mg Ni/m3

Key result

Dose descriptor:

NOAEC

Effect level:

0.125 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: overall effects

Remarks on result:

other: equivalent to 0.027 mg Ni/m3

Key result

Critical effects observed:

no

Conclusions:

No evidence of carcinogenic activity of the test substance nickel sulfate hexahydrate as aerosol has been revealed in rats in this 2-years inhalation study. The NOAEL was determined to be ca. 0.125 mg/m3 air, equivalent to 0.027 mg Ni/m3 air.

Reference 2

Endpoint:

carcinogenicity: inhalation

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

May 1988 to May 1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Reason / purpose for cross-reference:

other: reference to same study, different species (rat)

Reason / purpose for cross-reference:

other: refrence to same study, different species (rat)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)

GLP compliance:

yes

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Simonsen Laboratories, Gilroy, CA, USA.
- Age at study initiation: 6-week old
- Weight at study initiation: ~23 g
- Fasting period before study: not reported
- Housing: individually housed
- Diet: ad libitum, except during exposure
- Water: ad libitum, except during exposure

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17.2-29.6°C
- Humidity (%): 8-99%
- Air changes (per hr): 9-21/hour
- Photoperiod (hrs dark / hrs light): 12-h light/dark photo cycle

IN-LIFE DATES: May 1988 to May 1990

Route of administration:

inhalation: aerosol

Type of inhalation exposure (if applicable):

whole body

Vehicle:

other: distilled and deionized water

Remarks on MMAD:

MMAD / GSD: MMAD =2.08-2.52 µm

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Stainless steel multitiered whole exposure chambers (Hazleton, Aberdeen, MD, USA)
- Source and rate of air: High-efficiency particulate air filter (Flanders, Washington, DC)
- System of generating particulates/aerosols: Aerosols were generated by nebulization of test substance solutions (62.1 g/L in distilled and deionized water)
- Temperature, humidity, pressure in air chamber: Temp. 17.2-29.6 °C; humidity 8-99%
- Air flow rate: The aerosol was mixed with additional dilution air to achieve the proper concentration and flow rate.
- Method of particle size determination: Aerosol concentration was determined by taking three 2-h filter samples throughout the exposure day.
Real-time determination of aerosol concentration was made using real time aerosol monitor - model S units. Aerosol size was determined using cascade impactors. (The range of mass median aerodynamic diameters and GSD obtained throughout the study were 2.2-2.5 um and GSD=2.2)


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

VEHICLE: water

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Aerosol concentration was determined by taking three 2-h filter samples throughout the exposure day. Real-time determination of aerosol concentration was made using real time aerosol monitor - model S units. Aerosol size was determined using cascade impactors.

Duration of treatment / exposure:

6 h / d

Frequency of treatment:

5 days per week for a period of 2 years

Dose / conc.:

1 mg/m³ air (nominal)

Dose / conc.:

0 mg/m³ air (nominal)

Dose / conc.:

0.25 mg/m³ air (nominal)

Dose / conc.:

0.5 mg/m³ air (nominal)

No. of animals per sex per dose:

80 males and 80 females per group

Control animals:

yes, concurrent no treatment

Details on study design:

- Rationale for animal assignment: distributed randomly into groups of approximately equal initial mean body weights

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Animals were observed twice daily.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: conducted at the start of the study, weekly for 13 weeks, monthly during the remainder of the study, and at the end of the study period.

BODY WEIGHT: Yes
- Time schedule: conducted at the start of the study, weekly for 13 weeks, monthly during the remainder of the study, and at the end of the study period.

HAEMATOLOGY: Yes
- Blood was collected from the retroorbital sinus of as many as five male and five female mice at the 15-month interim evaluation.
- Hematology: hematocrit, hemoglobin, erythrocytes, mean erythrocyte volume, mean erythrocyte hemoglobin, mean erythrocyte hemoglobin concentration, reticulocytes, total leukocytes and differential, and nucleated erythrocytes.

Sacrifice and pathology:

GROSS PATHOLOGY/HISTOPATHOLOGY: Yes
Necropsy was performed on all animals.
The following organs were weighed at 7- and 15-months: brain, right kidney, liver, lung, spleen, and thymus.

Complete histopathology was performed on all mice. Gross lesions and tissues examined included: adrenal gland, bone, brain, clitoral gland, epididymis or oviduct, esophagus, heart, gallbladder, 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, preputial gland, prostate, salivary gland, seminal vesicle, skin, spleen, stomach, testis, thymus, thyroid gland, trachea, urinary bladder, and uterus.

Other examinations:

Ni levels in lung and kidney tissues were analyzed

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).

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The final mean body weights compared to the control group per 0.25 mg/m3, 0.5 mg/m3 and 1 mg/m3 exposure groups were 94 %, 97 % and 91 %, respectively for the male rats and 91 %, 94 % and 88 % for the females, respectively.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological 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):

Lung weights in exposed animals were greater than controls, this was considered to be related to inflammatory lung reactions that occurred in response to test substance exposure. At 15 months, the lung weights of in the high exposure group was 30-37 % more compared to the control.

Gross pathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

A spectrum of exposure-related nonneoplastic respiratory tract lesions seen after exposure included focal alveolar/bronchiolar hyperplasia, inflammation, and/or fibrosis of the lung and lymphoid hyperplasia of the lung-associated lymph nodes. Atrophy of the olfactory epithelium was also seen after exposure.

Histopathological findings: neoplastic:

no effects observed

Details on results:

Tissue Ni burden levels were below the level of detection at the 7- and 15-month evaluation periods.

HISTOPATHOLOGY: NON-NEOPLASTIC
Significantly increased incidences of non-neoplastic lung lesions reported for 2-year study:
-chronic active lung inflammation of 0.5 and 1 mg/m3 male mice, and 0.25, 0.5, and 1 mg/m3 female mice.
-macrophage hyperplasia of 0.5 and 1 mg/m3 male mice, and 0.25, 0.5, and 1 mg/m3 female mice.
-bronchialization of 0.5 and 1 mg/mg3 male mice, and 0.25, 0.5, and 1 mg/m3 female mice.
-interstitial infiltration of 1 mg/m3 male mice, and 0.5 and 1 mg/m3 female mice.
-alveolar proteinosis of 1 mg/m3 male mice, and 0.5 and 1 mg/m3 female mice.
-bronchial lymphoid hyperplasia of 1 mg/m3 male and female mice.
-bronchial macrophage hyperplasia of 0.5 and 1 mg/m3 male and female mice.
The incidence of atrophy of the olfactory epithelium at the end of the 2-year study was significantly increased in 0.5 and 1 mg/m3 male mice,
and in 1 mg/m3 female mice.

Result (carcinogenicity): negative

Key result

Dose descriptor:

LOAEL

Effect level:

0.25 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: chronic active lung inflammation

Remarks on result:

other: equivalent to 0.056 mg Ni/m3

Key result

Critical effects observed:

no

Conclusions:

On the basis of chronic active lung inflammation, the LOAEL was determined to be 0.056 mg Ni/m3 (0.25 mg nickel sulfate hexahydate/m3). No NOAEL could be determined. No evidence of a carcinogenic activity of nickel sulfate hexahydrate in mice was revealed.

Reference 3

Endpoint:

carcinogenicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

Please refer to IUCLID section 13 for justification of read across.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEC

Remarks:

test animal: rat

Effect level:

0.125 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: overall effects

Remarks on result:

other: equivalent to 0.027 mg Ni/m3

Key result

Dose descriptor:

LOAEL

Remarks:

test animal: mouse

Effect level:

0.25 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: chronic active lung inflammation

Remarks on result:

other: equivalent to 0.056 mg Ni/m3

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

0.027 mg/m³

Study duration:

chronic

Species:

rat

Quality of whole database:

study conducted similar to OECD Guideline, well documented publication

Carcinogenicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Please refer to the field 'Additional information' below.

Classification, Labelling, and Packaging Regulation (EC) No 1272/2008

The available data were considered reliable and suitable for classification purposes under Regulation (EC) No 1272/2008. Based on the results, the target and source substances are classified for carcinogenicity into category 1A and labelled with H350 (may cause cancer) by inhalation, as amended for the fifteenth time in Regulation (EU) No 2020/1182.

Additional information

No data on the substance itself is available. Read across was therefore applied to the available data obtained from studies with Nickel sulfate hexahydrate (CAS 10101-97-0).

Oral exposure

In an oral carcinogenicity study according to OECD 451 and EPA OPPTS 870.4200, male and female Fischer CDF(344)/CrlBR rats were assigned to the dose groups 0 (group 1), 10 (group 2), 30 (group 3) or 50 mg/kg bw/d (group 4). The test group animals (60 males and 60 females per dose) received the test material nickel sulphate hexahydrate daily via gavage (amount 10 mL, vehicle: water) for a period of 104 weeks. For the entire 104 weeks period there was no apparent treatment-related effect on mortality in males. In females, there was an increasing exposure–response trend in mortality relative to the controls (p<0.008). Body weights decreased in an exposure-dependent manner, with significantly decreased body weights observed in the two highest exposure groups for males and females (groups 3–4). Reductions in weight gain relative to controls at study week 103 reached the level of biological significance (>10 % decrease) in the group 3 and 4 males and the group 4 females. This significant weight reduction indicates that the Maximum Tolerated Dose was reached in this study for both males and females. No notable differences were observed between controls and treated animals for the hematology, biochemistry and urinalysis parameters measured during the toxicokinetic satellite study. The treatment did not produce an exposure-related increase in tumorigenicity. Only one tumor type in one exposure group was statistically different from the study controls (keratoacanthoma in the 10 mg/kg/day males), but no exposure–response relationship was observed and this is a common tumor type. The results of this study indicate that nickel sulfate hexahydrate does not cause carcinogenicity to rats when administered orally. Based on the decreased body weights the NOAEL of the test substance was determined to be 10 mg/kg bw/d.

Inhalation exposure

An inhalation carcinogenicity study was conducted similar to OECD Guideline 453 with F344/N rats. The test animals were exposed to nickel sulphate hexahydrate as aerosol in the following nominal concentrations: 0, 0.125, 0.25, 0.5 and 1 mg test substance/m3 air. One dose group consisted of 63 to 65 male and 63 to 64 female rats. The animals were treated for 2 years, 6h/d for 5 days per week. Detailed clinical observations were performed every 4 weeks during the study. After study termination, complete necropsies were done on all animals. As a result, no effects concerning clinical signs or mortality were observed. The final mean body weights compared to the control group per 0.125 mg/m3, 0.25 mg/m3 and 0.5 mg/m3 exposure groups were 99 %, 101 % and 98 %, respectively for the male rats and 97 %, 97 % and 94 % for the females, respectively. The lung weights in the exposed animals were greater than in the controls, this was considered to be related to inflammatory lung reactions that occurred in response to test substance exposure. At 15 months, the lung weights of in the high exposure group was 33-41 % more compared to the control. There were no increases in lung neoplasms in rats exposed to the test substance. A spectrum of exposure-related non-neoplastic respiratory tract lesions seen after exposure included focal alveolar/bronchiolar hyperplasia, inflammation, and/or fibrosis of the lung and lymphoid hyperplasia of the lung-associated lymph nodes. Atrophy of the olfactory epithelium was also seen after exposure. Based on the inflammatory effects in the lung the NOAEL of the test substance as aerosol was determined to be ca. 0.125 mg/m3 air, equivalent to 0.027 mg Ni/m3 air.

The same study was further conducted with male and female B6C3F1 mice. The test animals were exposed to the test material as aerosol in the following nominal concentrations: 0, 0.25, 0.5 and 1 mg test substance/m3 air. One dose group consisted of 80 male and 80 female mice. The animals were treated for 2 years, 6h/d for 5 days per week. Detailed clinical observations were performed every 4 weeks during the study. After study termination, complete necropsies were done on all animals. As a result, no effects concerning clinical signs or mortality were observed. The final mean body weights compared to the control group per 0.25 mg/m3, 0.5 mg/m3 and 1 mg/m3 exposure groups were 94 %, 97 % and 91 %, respectively for the male rats and 91 %, 94 % and 88 % for the females, respectively. The lung weights in the exposed animals were greater than in the controls, this was considered to be related to inflammatory lung reactions that occurred in response to test substance exposure. At 15 months, the lung weights of in the high exposure group was 30-37 % more compared to the control. There were no increases in lung neoplasms in mice exposed to the test substance. A spectrum of exposure-related non-neoplastic respiratory tract lesions seen after exposure included focal alveolar/bronchiolar hyperplasia, inflammation, and/or fibrosis of the lung and lymphoid hyperplasia of the lung-associated lymph nodes. Atrophy of the olfactory epithelium was also seen after exposure. Based on the inflammatory effects in the lung the LOAEL of the test substance as aerosol was determined to be 0.25 mg/m3 air, equivalent to 0.056 mg Ni/m3 air.

 

Conclusion

Based on the available data, the read-across substance nickel sulfate hexadydrate did not show a carcinogenic potential in rats following oral administration. Based on the lower dermal absorption rate of nickel, it is assumed that dermal exposure of the source substance or another nickel compound including the target substance would also not lead to cancer.

The above mentioned inhalation studies with rats and mice did not reveal a carcinogenic effect. However, an increase in the number of non-neoplastic lesions as summarized above was noted. The source substances CAS 373-02-4, CAS 7786-81-4, CAS 7791-20-0 (please refer to the read across justification) are classified as Carc. 1A H350i (may cause cancer by the inhalation route), (please refer to the respective ECHA disseminated dossiers). The justification for classification includes epidemiological data also discussed in the EU Risk assessment for Nickel and Nickel compounds (2008/2009): Workers exposed to dust containing nickel sulphate and/or nickel chloride in the presence of variable amounts of water insoluble nickel compounds were shown to have elevated risk of lung and nasal cancer. The source substances are therefore classified for carcinogenicity (inhalation route). In line with their classification, classification of the target substance nickel propionate into category Carc 1A is therefore justified.