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Administrative data

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Cross-reference
Reason / purpose for cross-reference:
reference to same study
Reference
Endpoint:
acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
not applicable
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 401 (Acute Oral Toxicity)
GLP compliance:
not specified
Test type:
standard acute method
Limit test:
yes
Species:
rat
Strain:
other: Crj: CD(SD) IGS rats (SPF)
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Japan, Inc
- Age at study initiation: 5 wk
- Weight at study initiation: 125-145 g (male) and 116-130g (female)
- Fasting period before study: 18h
- Diet (ad libitum): pellet diet (MF, Oriental Yeast co, Ltd)
- Water (ad libitum): tap water irradiated by UV rays after passing through a 5µm filter
- Acclimation period: 6days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22.2 ± 2
- Humidity (%): 55 ± 15
- Air changes (per hr): 12 changes per hour
- Photoperiod (hrs dark / hrs light): 12 hrs dark/12 hrs light

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on oral exposure:
MAXIMUM DOSE VOLUME APPLIED: the dosing volume was set at 10mg/kg and the dose volume for individual animals was calculated based on the body weight measured just before dosing

DOSAGE PREPARATION (if unusual): done on the administration day

Doses:
2000mg/kg
No. of animals per sex per dose:
12
Control animals:
yes
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: body weights of all animals were measured before dosing and on days 4, 8, and 15 (day of administration was designated as day 1)
- Necropsy of survivors performed: no
- Other examinations performed:
clinical signs: observed 5 times (shortly before dosing, and 0.5, 1, 3 and 5h after dosing) on the those day and thereafter once a day for 14 days
body weight: measured before dosing and on days 4, 8, and 15
Statistics:
Barlett's test: to test the homogeneity of the variances of the data
one way analysis of variance: used when to variances of the treatment group and the control group were homogenous; to analyze statistical significances in the numerical data (body weight, food consumption, hematology, blood chemistry, and organ weights)
Kruskal-Wallis test: used when to variances of the treatment group and the control group were heterogenous; to analyze statistical significances in the numerical data (body weight, food consumption, hematology, blood chemistry, and organ weights)
Dunnett's test or Dunnett-type ranksum test: to examine statistical significances in the data between groups
chi square test: to examine statistical significances in graded categorical data (urinalysis)
Preliminary study:
a preliminary study was done in which no death were observed
Key result
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Based on:
test mat.
Mortality:
No mortality observed
Clinical signs:
other: No abnormalities in clinical signs observed
Gross pathology:
Necroscopy:
no abnormalities observed
Other findings:
spontaneous changes: in one male of the 2000 mg/kg group pelvic dilatation of the kidneys was observed

none

Interpretation of results:
GHS criteria not met
Conclusions:
Tests done according to standard protocol. Good quality and considered useful for setting the reference value for acute oral toxicity (LD50>2000mg/kg)

Although this study represented an out of date test guideline as it was deleted on 17th December 2002 and replaced with the fixed dose (TG 420 [4]) and acute toxic class (OECD TG 425 [5]) methods, it meets in light of current test guidelines (i.e. TG 420) the minimum animal required of 5 animals (Asakura et al. used 12)
The preference within the current test guideline is that test substances are preferentially administered as an aqueous solution/suspension/emulsion followed in order of preference by a solution/suspension/emulsion in oil (e.g. corn oil) as used by Asakura et al).
Executive summary:

A limit study with Crj:CD (SD) IGS rats (SPF) was carried out according to OECD guideline no 401 to assess the oral LD50. No deaths and no abnormalities in clinical signs, body weights, and necropsy findings were observed for any of the animals. An LD50 value >2000mg/kg bw was reported.

Data source

Reference
Reference Type:
publication
Title:
Oral toxicity of indium in rats: single and 28-day repeated administration studies.
Author:
Asakura K, Satoh H, Chiba M, Okamoto M, Serizawa K, Nakano M and Omae K
Year:
2008
Bibliographic source:
J Occup Health. 50(6):471-9

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)
GLP compliance:
not specified
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Indium
EC Number:
231-180-0
EC Name:
Indium
Cas Number:
7440-74-6
Molecular formula:
In
IUPAC Name:
indium
Details on test material:
- Name of test material (as cited in study report): Indium
- Analytical purity: 99%
- Lot/batch No.: 67246G
- Stability under test conditions: stable based on the characteristics of indium
- Storage condition of test material: room temperature
- Other: particle diameter : M45 µm pass

Test animals

Species:
rat
Strain:
Crj: CD(SD)
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Japan, Inc
- Age at study initiation: 5 wk
- Weight at study initiation: 125-145 g (male) and 116-130g (female)
- Fasting period before study: 18h
- Diet (ad libitum): pellet diet (MF, Oriental Yeast co, Ltd)
- Water (ad libitum): tap water irradiated by UV rays after passing through a 5µm filter
- Acclimation period: 7days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22.2 ± 2
- Humidity (%): 55 ± 15
- Air changes (per hr): 12 changes per hour
- Photoperiod (hrs dark / hrs light): 12 hrs dark/12 hrs light

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on oral exposure:
MAXIMUM DOSE VOLUME APPLIED: the dosing volume was set at 10mg/kg and the dose volume for individual animals was calculated based on the body weight measured just before dosing
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
MAXIMUM DOSE VOLUME APPLIED: the dosing volume was set at 10mg/kg and the dose volume for individual animals was calculated based on the body weight measured just before dosing
Duration of treatment / exposure:
28 days and a 14 day recovery period after completion of the dosing period
Frequency of treatment:
once daily in the morning throughout the 28-day dosing period
Doses / concentrationsopen allclose all
Dose / conc.:
40 mg/kg bw/day (nominal)
Dose / conc.:
200 mg/kg bw/day (nominal)
Dose / conc.:
1 000 mg/kg bw/day (nominal)
No. of animals per sex per dose:
1000 mg/kg : 12 F + 12 M
200 mg/kg: 6F + 6M
40mg/kg: 6F+ 6M
0 mg/kg: 12F + 12M
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale:
Prior tho the 28 day repeated oral dose toxicity study, a preliminary dose finding "A fourteen-day repeated oral toxicity preliminary study in rats" with dose levels : 0, 100, 500 and 1000 mg/kg was conducted. No changes attributable to the test substance were observed in clinical signs, body weights, hematology or organ weights (brain, thymus, liver, kidney, adrenal glands, spleen, testis and ovary) on necropsy. As such, the highest dose level was set at 1000mg/kg and the middle and the lower dose levels at 200 and 40 mg/kg respectively

- Rationale for animal assignment (if not random): animals were assigned to groups by the stratified-by-weight randomization method so that they were evenly assigned with respect to the mean body weight.

Examinations

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

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice a day ( before and after administration) throughout the dosing period and once day in the morning during the recovery period

BODY WEIGHT: Yes
- Time schedule for examinations: once a week

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: on the days of the sheduled necropsy after the completion of dosing and recovery periods (days 29 and 43)
- Anaesthetic used for blood collection: Yes : ip injection of thiopental sodium
- Animals fasted: No data
- How many animals: 12 M and 12 F


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: on the days of the sheduled necropsy after the completion of dosing and recovery periods (days 29 and 43)
- Animals fasted: No data
- How many animals:12 M and 12 F

URINALYSIS: Yes
- Time schedule for collection of urine: collected on day 27
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data


NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
HISTOPATHOLOGY: Yes : on the heart, liver , spleen, kidneys, and adrenals obtained from animals of the control and 1000 mg/kg groups and on gross lesions of any group
Other examinations:
none
Statistics:
Barlett's test: to test the homogeneity of the variances of the data
one way analysis of variance: used when to variances of the treatment group and the control group were homogenous; to analyze statistical significances in the numerical data (body weight, food consumption, hematology, blood chemistry, and organ weights)
Kruskal-Wallis test: used when to variances of the treatment group and the control group were heterogenous; to analyze statistical significances in the numerical data (body weight, food consumption, hematology, blood chemistry, and organ weights)
Dunnett's test or Dunnett-type ranksum test: to examine statistical significances in the data between groups
chi square test: to examine statistical significances in graded categorical data (urinalysis)

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
effects observed, treatment-related
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
not specified
Details on results:
CLINICAL SIGNS AND MORTALITY: No abnormal clinical signs observed in any animal during the dosing and recovery periods

BODY WEIGHT AND WEIGHT GAIN: No significant body weight difference between the control group and any treatment group

HAEMATOLOGY: no significant hematological change attributable to indium after the dosing period. After the recovery period, a significantly higher value of the ratio of lymphocyte and a significantly lower value of the ratio of monocyte were observed in females of the 1000mg/kg group, as compared with the control group

CLINICAL CHEMISTRY no significant differences in blood chemistry between the control group and any treatment group after the indium-dosing group. After the recovery period, a significantly lower value of total chlolesterol was observed in females of the 1000mg/kg group

URINALYSIS: During the dosing period, a significantly higher value of urobilinogen was observed in females of the 1000mg/kg group, as compared to with the control group

ORGAN WEIGHTS: significantly lower values of absolute kidney weights in female rats of the 200mg/kg group after the dosing period.

HISTOPATHOLOGY: NON-NEOPLASTIC:
spontaneous changes in histopathological findings were observed in animals of the 1000mg/kg groups after the dosing period: focal myocardial degeneration/fibrosis in the heart, periportal inflammaroty cells and microgranuloma in the liver, basophilic renal tubule , renal cysts, hyaline droplets of proximal tubular epithelium and focal inflammatory cell infiltration in the kidneys and an increase in lipid droplets of the fascicular zone in the adrenals. Most of the changes were also observed in the control group as well as in the 1000 mg/kg group


Effect levels

Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw (total dose)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
clinical biochemistry
clinical signs
haematology
histopathology: non-neoplastic
mortality

Target system / organ toxicity

Critical effects observed:
no

Any other information on results incl. tables

The authors discuss that haematological and blood chemistry changes may not be related to indium because they were not observed at the end of the dosing period and both total white blood cell count and overall nutritional condition were stable. Also they considered the significantly higher value of urobilinogen observed in females of the 1000 mg/kg group during the dosing period as not necessarily related to indium because neither liver dysfunction nor anemia coincided with it. The authors state that experiments using more animals might demonstrate the irrelevancy of indium to changes of parameters more clearly.

Concerning pathology, the significantly lower values of absolute kidney weights in female rats of the 200mg/kg group after the dosing period, was considered as a spontaneous change because it occurred without dose-dependency and relative kidney weights were not significantly different between treated groups and the control group.

The hispathological changes observed in several rats were also considered as changes that were unrelated to indium because they were slight, nonspecific and not dose dependent.

Applicant's summary and conclusion

Conclusions:
Under the test conditions, NOAEL of the test material in rats was determined to be 1000 mg/kg for males and females
Executive summary:

This study was conducted to evaluate the subchronic toxicity (28 days) of the test material in rats Crj:CD(SD) IGS rats (SPF).

The study followed was similar to OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity in Rodents).

Rats of both sexes received by oral gavage the test material at 0, 20, 400 and 1000 mg/kg for 28 days. No changes related to indium with regard to clinical signs, body weights, food consumption, hematology, blood chemistry, urinalysis, organ weights, necropsy or histopathological findings were reported.

Under these test conditions, NOAEL of the test material in rats was determined to be 1000 mg/kg for males and females