Registration Dossier

Administrative data

Endpoint:
acute toxicity: oral
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
2002-07-02 to 2002-08-20
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Well documented, scientifically sound study that was conducted in accordance with GLP and OECD Guideline 423, limit test. The reliability of this study for the substance tested is a K1, but in application of read-across to a different substance ECHA’s guidance specifies that the score can be a maximum of K2. Due to similar physical-chemical properties, similar or lower transformation/dissolution results and similar or lower in vitro bioaccessibility in synthetic body fluids for tungsten dioxide (the target substance) than the source substances, the resulting toxicity potential would also be expected to be similar or lower, so read-across is appropriate. Therefore, the dose descriptors are expected to be sufficiently similar or higher for the target substance, and read-across to the source chemical is adequately protective. For more details refer to the attached description of the read-across approach.
Justification for type of information:
REPORTING FORMAT FOR THE CATEGORY APPROACH
1. HYPOTHESIS FOR THE ANALOGUE APPROACH: The hypothesis is that properties are likely to be similar or follow a similar pattern because of the presence of a common metal ion, in this case tungstate.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES):
Source: Tungsten Trioxide
Target: Tungsten Dioxide
Cross-reference
Reason / purpose:
read-across: supporting information

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2002

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)
Qualifier:
according to
Guideline:
EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)
GLP compliance:
yes
Test type:
acute toxic class method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Tungsten oxide (WO3)
- Physical state: Yellow to greenish powder
- Analytical purity: 99.88%
- Purity test date: 2002-05-28
- Stability under test conditions: 5 years
- Storage condition of test material: Ambient temperature, dry
- Melting Point: Approx. 1473 degrees C
- pH: 6.1 (aqueous suspension, 100 g/L)
- Solubility in water: <10 mg/L WO3

Test animals

Species:
rat
Strain:
other: Crl:CD(SD)IGS BR
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River WIGA
- Age at study initiation: Approximately 8 weeks
- Weight at study initiation: 166-167 g (females), 195-201 (males)
- Fasting period before study: Yes; the feed was withdrawn the evening before the administration of the test substance and was offered again about three hours afterwards.
- Housing: Single caging in Makrolon cages type III (39 cm x 23 cm bottom area, 18 cm height). Wire mesh lids. Sanitation of cages once a week.
- Diet: Altromin 1324 forte, gamma irradiated with 25 kGy60Co, ad libitum.
- Water: Tap water from an automatic watering system, ad libitum.
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): average of 22.2 C
- Humidity (%): Average of 64.7%
- Air changes (per hr): 12/hr
- Photoperiod (hrs dark / hrs light): 12 dark/12 light (6 am to 6 pm)

IN-LIFE DATES: From: 2002-07-02 To: 2002-07-17

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on oral exposure:
DOSE VOLUME APPLIED: 10 mL /kg body weight

DOSAGE PREPARATION: Doses of 2000 mg/kg body weight were prepared as suspensions in deionised water. Suspensions were prepared freshly before administration and were administered within 5 minutes after the preparation.

CLASS METHOD (if applicable)
- Rationale for the selection of the starting dose: As requested by the sponsor
Doses:
2000 mg/kg body weight (in two steps)
No. of animals per sex per dose:
3 males and 3 females
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
- Clinical observations- 0-0.5, 0.5-1, 1-2, 2-4, and 4-6 hours after administration and then at least once a day for a total of 2 weeks. Observations included but were not limited to changes in skin, fur, eyes, the occurrence of secretions and excretions, autonomic activity, changes in gait, posture and the presence of convulsions.
- Body weights- before administration, day 7, and day 14 post administration. Bodyweight gain was calculated for each week of the study, i.e. between 0 and 7 days post administration and 7 and 14 days post administration.
- Necropsy of survivors performed: Yes
Statistics:
no data

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Remarks on result:
other: No toxic effects were present after a single dose of 2000 mg/kg of the test substance.
Mortality:
None
Clinical signs:
All animals were normal during the whole observation period.
Body weight:
All animals gained weight in both weeks post administration.
Gross pathology:
All animals were normal at the necropsy, 14 days post administration.
Other findings:
There was no significant sex difference in the response to the test substance at 2000 mg/kg body weight.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
A test according to OECD 423 was conducted to determine the acute oral toxicity of tungsten trioxide to 8 week old male and female rats (starin Crl:CD(SD)IGS BR). 3 male and 3 female fasted rats were given a single oral dose of tungsten trioxide of 2000 mg/kg bw in water. The substance was administered in two steps. Animals were subsequently observed for 14 days. No toxic effects were present after a single dose of 2000 mg/kg of the test substance, LD50 > 2000 mg/kg bw. Thus, ist can be concluded that tungsten trioxide is practically nontoxic to male and female rats.
Executive summary:

No acute oral toxicity data of sufficient quality are available for tungsten dioxide (target substance). However, acute oral toxicity data are available for sodium tungstate (source substance), which will be used for reading across. Due to lower water solubility and lower toxicity for the target substance compared to the source substance, the resulting read across from the source substance to the target substance is appropriate as a conservative estimate of potential toxicity for this endpoint. In addition, read across is appropriate because the classification and labelling is more protective for the source substance than the target substance, the PBT/vPvB profile is the same, and the dose descriptors are, or are expected to be, lower for the source substance. For more details, refer to the read-across category approach included in the Category section of this IUCLID submission and/or as an Annex in the CSR.