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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
no data
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: In principle, the study results are well documented with some exceptions: the test material inadequately characterised and histopathology is poorly reported.
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
publication
Title:
Twenty-eight-day oral toxicity, genotoxicity, and gender-related tissue distribution of silver nanoparticles in Sprague-Dawely rats.
Author:
Kim, Y.S.; et al.
Year:
2008
Bibliographic source:
Inhalation Toxicology 20, 575-583

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity in Rodents)
Deviations:
not specified
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: silver nanoparticles (60nm), not further characterised; source: Namatech (Korea)
Details on test material:
- Name of test material (as cited in study report): silver nanoparticles
- Molecular formula (if other than submission substance): Ag
- Molecular weight (if other than submission substance): 107.87
- Physical state: solid
- Analytical purity: at least 99.98 % pure
- Other: silver nano particles (52.7 - 70.9 nm; average 60 nm), purchased form NAMATECH Co., Ltd. (Korea)

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: OrientBio (Korea)
- Age at study initiation: 6 weeks old at start of exposure
- Weight at study initiation: about 283 g for the males and 192 g for the females
- Housing: polycarbonate cages (max. 3 rats per cage)
- Diet: rodent diet (Harlan Tek lab, Plaster International Co., Korea), ad libitum except before necropsy when food was withheld for 24 h
- Water: filtered water, ad libitum
- Acclimation period: 2 weeks before starting the experiment

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23± 2 °C
- Humidity (%): 55 ± 7 %
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: unspecified
Vehicle:
CMC (carboxymethyl cellulose)
Remarks:
aqueous, 0.5 % solution (from Sigma, USA)
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS: no details

VEHICLE
- Justification for use and choice of vehicle (if other than water): CMC is a standard vehicle in toxicity studies
- Amount of vehicle (if gavage): dosing volumes were 10 mL/kg
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
no data
Duration of treatment / exposure:
28 days
Frequency of treatment:
daily
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
30 mg/kg/d (low dose)
Basis:
other: actual administered
Remarks:
Doses / Concentrations:
300 mg/kg/d (middle dose)
Basis:
other: actual administered
Remarks:
Doses / Concentrations:
1000 mg/kg/d (high dose)
Basis:
other: actual administered
No. of animals per sex per dose:
10 male and 10 female rats per group
Control animals:
yes, concurrent vehicle
Details on study design:
no data
Positive control:
no data

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: No data

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: no data

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

FOOD EFFICIENCY: No data

WATER CONSUMPTION: No data

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes, blood was drawn from the abdominal aorta
- Time schedule for collection of blood: after 28 days of exposure
- Anaesthetic used for blood collection: ether
- Animals fasted: for 24 hours
- How many animals: all
- Parameters checked: platelet counts, MPV, haemoglobin, haematocrit, RBC, WBC, MCV, MCH, MCHC, RDW, number of neutrophils, number of lymphocytes, numberof monocytes, number of eosinophils, percent of eosinophils, number of basophils, percent of basophils

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: after 28 days of exposure
- Animals fasted: for 24 hours
- How many animals: all
- Parameters checked: ALB, ALP, Ca, CHO, CRE, gamma-GT, GLU, GOT, GPT, inorg. phosphorus, LDH, Mg, total protein, uric acid, blood urea nitrogen, total bilirubin, creatine phosphokinase, Na, K, Cl, triglycerine, ratio of albumin to globulin

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
Before necropsy food was withheld for 24 hours. Rats were anesthetised with ether. After collection of blood rats were sacrificed by cervical dislocation.

GROSS PATHOLOGY: Yes
- The following organs were removed, weighed and fixed: adrenal glands, bladder, testes, ovaries, uterus, epididymis, seminal vesicle, heart, thymus, thyroid gland, trachea, esophagus, tongue, prostrate, lungs, nasal cavity, kidneys, spleen, liver, pancreas, and brain.

HISTOPATHOLOGY: Yes.
- The above mentioned organs were stained and examined under light microscope.
Other examinations:
Silver distribution study:
- After wet digestion using a flameless method, the tissue concentration of silver was analysed by AAS.
Statistics:
A multiple variance analysis and Duncan's multiple range tests were used to compare the body weights, organ weights, and results of the blood biochemistry and haematology for the three experimental groups with those of the fresh-air control rats. A value of p <0.05 indicated statistical significance.

Results and discussion

Results of examinations

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:
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:
effects observed, treatment-related
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
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
- No distinct clinical signs were observed during the treatment period.
- No mortality occured.

BODY WEIGHT AND WEIGHT GAIN
- No significant changes of body weights were observed in male and female animals.

FOOD CONSUMPTION
- No significant differences were observed between treated and control animals.

HAEMATOLOGY
- In male rats, the mean corpuscular vlume (MCV) was significantly increased (p<0.05) in high dose males (1000 mg/kg bw/d) only.
- In female rats, red blood cells, hemoglobin and hematocrit were significantly increased (p<0.05) in mid and high dose animals (300, 1000 mg/kg bw/d).
- The active partial thromboplastine time (APTT) was significantly decreased (p<0.05) in high dose females.

CLINICAL CHEMISTRY
- Significantly increased levels of ALP were observed in high (1000 mg/kg bw/d) and mid dose (300 mg/kg bw/d) males (p<0.01 and 0.05, respectively) and high dose females (p<0.05).
- Cholesterol levels were increased in mid (not statistically significant) and high dose males (p<0.05) and mid and high dose females (p<0.01).
- Total protein was significantly decreased in high dose male rats (p<0.05).

ORGAN WEIGHTS
- No significant effects on organ weights were observed.

HISTOPATHOLOGY: NON-NEOPLASTIC
- Increased incidences of bile duct hyperplasia around the central vein were observed in livers of male and female animals in a dose-dependent way.

Effect levels

Dose descriptor:
other:
Basis for effect level:
other: see 'Remark'
Remarks on result:
not measured/tested
Remarks:
Effect level not specified (migrated information)

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
Treatment of male and female rats with silver nanoparticles for 28 days revealed effects on red blood cell parameters at and above 300 mg/kg bw/d. Evidence of liver damage was observed by increases in alkaline phosphatase, cholesterol and total protein levels in mid and high dose animals treated with 300 or 1000 mg/kg bw/d. However, the information on histopathological findings is very limited, and it cannot be ruled out that bile duct hyperplasia in livers described already for low dose group animals are treatment-related. Thus, no NOAEL was defined based on the results of the study.
Silver deposits were observed dose-dependently in various organs of all treatment groups.