Silver carbonate

Repeated dose toxicity: oral

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: see 'Remark'

Remarks:

In principle, the study results are well documented with one exception: histopathological effects are described only very briefly and it is not possible to evaluate whether the findings of bile duct hyperplasia in livers observed at all dose groups are of toxicological relevance.

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:

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

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Deviations:

not specified

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Silver

EC Number:

231-131-3

EC Name:

Silver

Cas Number:

7440-22-4

Molecular formula:

Ag

IUPAC Name:

Silver

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 or test system 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 / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
30 mg/kg/d (low dose)
Basis:
other: actual administered

Doses / concentrations 2

Remarks:

Doses / Concentrations:
300 mg/kg/d (middle dose)
Basis:
other: actual administered

Doses / concentrations 3

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
- Increesaed 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

Basis for effect level:

other: no NOAEL identified; see details on results and conclusions in technical dossier

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.