Nickel monoxide

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April 21, 2009 - October 8, 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline Study

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 425 (Acute Oral Toxicity: Up-and-Down Procedure)

Deviations:

no

Principles of method if other than guideline:

AMENDMENT TO THE FINAL PROTOCOL
At the request of the Sponsor, the single dose limit dose was changed to 11,000 mg/kg in order to accommodate the calculation of an LD50 value greater than the upper limit dose level of 5,000 mg/kg selected in the protocol. The current dose progression was stopped and a new dosing progression was initiated using a starting dose level of 5,000 mg/kg. The subsequent dose levels in the progression were 6,300, 7,930, 9,990, and 11,000 mg/kg. These dose levels are manually calculated from the starting dose level of 5,000 mg/kg, using a factor of 1.26 and rounded down to the nearest 10 (to provide a tighter dose progression and yielding an approximate sigma value of 0.1). Prior to this Amendment, a second animal (No. 3110 see Deviation #1) had already been dosed at 5,000 mg/kg. Animals Nos. 3101-3108 and Animal No. 3110 were not included in the calculation of the LD50.

DEVIATION FROM FINAL PROTOCOL
A second animal (Animal No. 3110) was dosed at 5,000 mg/kg prior to the scientist being notified of the limit dose increase (see Amendment #1). Animal No. 3110 did not follow the dose progression based on the amended limit dose. This animal was removed from the dosing scheme and the calculation of the estimated LD50. This deviation does not adversely affect the results of this study.

GLP compliance:

yes (incl. QA statement)

Test type:

up-and-down procedure

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Nickel monoxide

EC Number:

215-215-7

EC Name:

Nickel monoxide

Cas Number:

1313-99-1

Molecular formula:

NiO

IUPAC Name:

oxonickel

Details on test material:

- Name of test material (as cited in study report): Nickel oxide black, Code #N105-PTL
- Physical state: black solid
- Composition of test material, percentage of components: Nickel Monoxide – 96.4%
- Solubility: insoluble in cold water
- Expiration date of the lot/batch: Not Applicable
- Stability under test conditions: test substance was expected to be stable for the duration of testing
- Storage condition of test material: tightly closed under nitrogen
- Other: Documentation of the methods, synthesis, fabrication, or derivation of the test substance retained by Umicore. Rue du Marais 31, 1000 Bruxelles. BE Belgium.

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Ace Animals, Boyertown, PA on April 7, 21, 28, May 12, June 2 and 16, 2009.
- Age at study initiation: young adult, 9-10 weeks
- Weight at study initiation: 160-203 grams at experimental start.
- Fasting period before study: overnight prior to dosing
- Housing: singly housed in suspended stainless steel caging with mesh floors; litter paper was placed beneath the cage and was changed at least three times per week
- Diet (e.g. ad libitum): ad libitum, Purina Rodeng Chow #5012
- Water (e.g. ad libitum): tap water ad libitum
- Acclimation period: 7 - 17 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-23 °C
- Humidity (%): 34-71%
- Photoperiod (hrs dark / hrs light): 12-hour light/dark cycle

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: DMPS

Details on oral exposure:

VEHICLE
The test substance was administered as a 30% w/w mixture in DMPS.

MAXIMUM DOSE VOLUME APPLIED:
11,000 mg/kg

DOSAGE PREPARATION (if unusual):
Due to the high volume of test mixture to be administered for the 5,000 mg/kg dose level and above (12.47-27.42 ml/kg), each animal's dose was divided into two or three approximately equal portions, administered two hours apart.

Doses:

5,000 mg/kg
6,300 mg/kg
7,930 mg/kg
9,990 mg/kg
11,000 mg/kg

No. of animals per sex per dose:

1 animal for doses 5,000, 6,300, and 11,000 mg/kg
2 animals for doses 7,930 and 9,990 mg/kg

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days (or other?): 14 days
- Frequency of observations and weighing: cage-side observations during the first several hours post-dosing and at least once daily thereafter for 14 days
- Necropsy of survivors performed: yes; gross necropsies performed on all animals, tissues and organs of the thoracic and abdominal cavities were examined
- Other examinations performed: clinical signs, body weight, organ weights, histopathology, other: individual body weights were recorded prior to test substance administration (initial) and again on Days 7 and 14 (termination) following dosing. Cage-side observations included mortality, signs of gross toxicity, and behavioral changes including: gross evaluation of skin and fur, eyes and mucous membranes, respiratory, circulatory, autonomic and central nervous systems, somatomotor activity and behavior pattern. Particular attention was directed to observations of tremors, convulsions, salivation, diarrhea, and coma.

Statistics:

The Acute Oral Toxicity (Guideline 425) Statistical Program (Weststat, version 1.0, May 2001) was used for all data analyses including: dose progression selections, stopping criteria determinations and/or LD50 and confidence limit calculations.

Results and discussion

Effect levels

Sex:

female

Dose descriptor:

LD50

Effect level:

8 796 mg/kg bw

Based on:

test mat.

Remarks on result:

other: in DMPS as vehicle

Mortality:

2 of the 7 animals died before day 7, and 1 of the remaining animals died after day 7 but before day 14. All the other animals survived through day 14.

Clinical signs:

other: 5,000 and 6,300 mg/kg Dose Levels (1 animal each): Following administration, both animals exhibited an oily stain on the base of the tail, however, these animals recovered by Day 2 and appeared active and healthy for the remainder of the study. 7,930 m

Gross pathology:

5,000 and 6,300 mg/kg Dose Levels (1 animal each):No gross abnormalities were noted for these animals when necropsied at the conclusion of the 14 day observation period.

7,930 mg/kg Dose Level (2 animals): Gross necropsy of the decedent revealed red intestines. No gross abnormalities were noted for the euthanized animal necropsied at the conclusion of the 14-day observation period.

9,990 mg/kg Dose Level (2 animals): Gross necropsy of the decedent revealed discoloration of the liver and intestines. No gross abnormalities were noted for the euthanized animal necropsied at the conclusion of the 14-day observation period.

11,000 mg/kg Dose Level (1 animal): Gross necropsy of thc decedent revealed discoloration ofthe intestines.

Other findings:

Not Applicable

Applicant's summary and conclusion

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: not specified

Conclusions:

Under the conditions of this study, the acute oral LD50 of nickel oxide black is estimated to be 8,796 mg/kg (Based on maximum likelihood) of body weight in female rats with a 95% PL confidence interval of 0 mg/kg (lower) to 20,000 mglkg (upper). [Note: PL = Profile-likelihood based on confidence interval].

Executive summary:

Eurofins Product Safety Laboratory (EPSL) reported the findings of an independent test evaluating the acute oral toxicity of black nickel oxide as determined by the acute toxicity up and down procedure in young female rats (carried out according to OECD Test # 425 guidelines and using GLP standards). Per the study Sponsor's request, the single dose limit dose was changed to 11,000 mg/kg in order to accommodate the calculation of an LD50 value greater than the upper limit dose level of 5,000 mg/kg selected in the protocol. The original dose progression (790, 1,000, 1,260, 1,580, 2,000, 2,510, 3,200, 4,000, 5,000 mg/kg) was stopped since none of the animals showed signs of toxicity, and a new dosing progression was initiated using a starting dose level of 5,000 mg/kg. The subsequent dose levels were manually calculated from the starting dose level of 5,000 mg/kg, using a factor of 1.26 and rounded down to the nearest 10 (to provide a tighter dose progression and yielding an approximate sigma value of 0.1), resulting in 6,300, 7,930, 9,990, and 11,000 mg/kg. Young adult female rats (n=1 or 2 per dose) were administered a single gavage dose of black nickel oxide solid (Code # N105-PTL). The black nickel oxide sample was composed of 96.4% nickel monoxide. The test substance was administered as a 30% w/w mixture in dimethylpolysiloxane (DMPS). All animals were observed for mortality, signs of gross toxicity, and behavioral changes at least once daily; body weight was monitored prior to dosing and again on Days 7 and 14, and all animals were necropsied following death or at study termination (Day 14). Following a single oral exposure to black nickel oxide preparation at doses of either 5,000 or 6,300 mg NiO/kg body weight, each animal exhibited an oily stain on the base of the tail. These animals recovered by Day 2, gained weight, and appeared active and healthy for the remainder of the study; there were no signs of gross abnormalities. Two animals were administered a single oral dose of 7,930 mg NiO/kg body weight. One animal died within four days of test substance administration and exhibited an oily stain on the base of the tail prior to death. Following administration, the surviving animal also exhibited an oily stain on the base of the tail, but it recovered by Day 3, gained weight, and appeared active and healthy. Gross necropsy of the decedent revealed red intestines, while there were no gross abnormalities noted for the animal that survived the 14-day observation period. Another two animals were administered a single oral dose of 9,990 mg NiO/kg body weight. One animal died within five days of test substance administration. This animal was hypoactive and exhibited an oily stain on the base of the tail, soft feces and ano-genital staining prior to death. Following administration, the surviving animal exhibited clinical signs that included ano-genital staining, reduced fecal volume, unthrifty appearance and an oily stain on the base of the tail; however, the animal recovered by Day 8, gained weight, and was active and healthy for the remainder 14-day observation period. Gross necropsy of the decedent revealed discoloration of the liver and intestines, while no gross abnormalities were noted for the animal that survived the 14-day observation period. Finally, the one animal administered 11,000 mg NiO/kg body weight died within four days of exposure. Prior to death, this animal was hypoactive and exhibited an oily stain on the base of the tail, reduced fecal volume and ano-genital staining. Under the conditions of this study, the acute oral LD50 of black nickel oxide is estimated to be 8,796 mg/kg (based on maximum likelihood) of body weight in female rats with a 95% PL confidence interval of 0 mg/kg (lower) to 20,000 mg/kg (upper). [Note: PL = Profile-likelihood based on confidence interval]. STUDY RATED BY AN INDEPENDENT REVIEWER.