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Diss Factsheets

Administrative data

Endpoint:
acute toxicity: dermal
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
1998-03-09 to 1999-06-24
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
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:
1. HYPOTHESIS FOR THE CATEGORY 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: Sodium Tungstate
Target: Tungsten Dioxide
3. CATEGORY APPROACH JUSTIFICATION: See Annex 3 in CSR
4. DATA MATRIX: See Annex 3 in CSR
Cross-reference
Reason / purpose for cross-reference:
read-across: supporting information

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1999
Report date:
1999

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 402 (Acute Dermal Toxicity)
GLP compliance:
yes
Test type:
standard acute method
Limit test:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Disodium wolframate
EC Number:
236-743-4
EC Name:
Disodium wolframate
Cas Number:
13472-45-2
Molecular formula:
Na2O4W
IUPAC Name:
Disodium dioxido(dioxo)tungsten
Details on test material:
- Name of test material (as cited in study report): Sodium Tungstate Dihydrate
- Physical state: White powder
- Analytical purity: 99.9%

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Harlan UK Ltd,Bicester, Oxon, England
- Age at study initiation: 8 to 11 wks
- Weight at study initiation: 235 to 300 g
- Housing: Individually in metal cages with wire mesh floors.
- Diet: ad libitum - Special Diet Services RM1(E) SQC expanded pellet.
- Water: ad libitum
- Acclimation period: 18 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 22.5 °C
- Humidity (%): 29 to 50%
- Air changes (per hr): 10 to 15
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: March 9, 1998 To: March 23, 1998

Administration / exposure

Type of coverage:
occlusive
Vehicle:
water
Details on dermal exposure:
TEST SITE
- Area of exposure: dorso-lumbar region
- % coverage: 10%
- Type of wrap if used: Porous gauze with a non-irritating dressing covered by a waterproof dressing encircled firmly around the trunk of the animal.


REMOVAL OF TEST SUBSTANCE
- Washing: with warm water and blotted dry with absorbent paper.
- Time after start of exposure:24 hrs


TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 2000 mg/kg bodyweight
- Constant volume or concentration used: yes
-Test material was applied by spreading it evenly over the prepared skin.
Duration of exposure:
24 hrs
Doses:
2000 mg/kg bodyweight, single dose.
Maximum practical concentration of 250% w/v in distilled water and administered at a dose volume of 0.8 mL/kg bodyweight.
No. of animals per sex per dose:
5 males and 5 females
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Animals were observed at lest twice daily for mortalities through 14 days.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, histopathology
-Clinical signs: Animals were observed soon after dosing and at frequent intervals for the remainder of Day 1. On subsequent days animals were observed once in the morning and again at the end of the experimental day (with the exception of Day 15 - morning only). The nature and severity of the clinical signs and time were recorded at each observation.
-Bodyweight: The bodyweight of each rat was recorded on Days 1 (prior to dosing), 8 and 15. Individual weekly bodyweight changes and group mean bodyweights were calculated.
-Macroscopic pathology: All animals were subjected to a macroscopic examination, which consisted of opening the abdominal and thoracic cavities. The macroscopic appearance of all tissues was recorded and macroscopic abnormalities were preserved.

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Mortality:
There were no deaths and no evidence of a systemic response in any animal throughout the study.
Clinical signs:
other: Slight erythema only was observed in three rats following removal of the dressings on Day 2 which was still evident in two animals on Day 3 before resolving in all instances by Day 4. No dermal irritation was seen in the remaining seven animals.
Gross pathology:
No macroscopic abnormalities were observed for animals killed at study termination on Day 15.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
In an acute dermal toxicity study according to OECD 402, 5 male and 5 femaleyoung adult Sprague-Dawley rats were dermally exposed to sodium tungstate dehydrate (99,9 %) in water for 24 hours to 10 % (body surface area)at a single dose of 2000 mg/kg bw (limit test). Animals then were observed for 14 days. There were no deaths and no evidence of a systemic response in any animal throughout the study. Slight erythema only was observed in three rats following removal of the dressings on Day 2 which was still evident in two animals on Day 3 before resolving in all instances by Day 4. No dermal irritation was seen in the remaining seven animals. No macroscopic abnormalities were observed for animals killed at study termination on Day 15. The acute lethal dose (LD50) was determined to be greater than 2000 mg/kg bw for male and female Sprague-Dawley rats. Thus, tungsten trioxide is considered to be practically nontoxic.

There were no deaths and no evidence of a systemic response in any animal throughout the study following a single dermal application of the test substance to rats at a dose level of 2000 mg/kg-bw. The acute lethal dose was determined to be greater than 2000 mg/kg bw.
Executive summary:

As no data on the acute dermal toxicity of tungsten dioxide are available, sodium tungstate dihydrate results are used for read-across. 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 sodium tungstate dihydrate (the source substance), 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 substance is adequately protective.