Tungsten hexafluoride

Endpoint summary

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1963

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study done before GLP was established. Read across justification is given in section 13 assessment reports: WF6 justification for read across

Qualifier:

no guideline followed

Principles of method if other than guideline:

Acute inhalation toxicity in the rat.
Maximum exposure: 60 min.

GLP compliance:

no

Remarks:

done before GLP was established

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

Weight: 100 - 120 g

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: no vehicle

Details on inhalation exposure:

Volume of the exposure chamber/housing was 400 l with an air flow of 200 l/min. An expansion tank and a manometer were used.
Constant temperature at 20 degree Celsius.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

60 min

Remarks on duration:

5, 15, 30 and 60 min

Concentrations:

various

No. of animals per sex per dose:

20 male rats per group/concentration

Control animals:

yes

Details on study design:

Groups of rats were exposed to various concentrations of hydrogen fluoride vapour for either 5, 15, 30 or 60 minutes. Surviving rats were weighed daily and observed for 14 days after exposure. Clinical observations were made following exposure, body weights were recorded daily and mortalities recorded.

Statistics:

The LC50 values for each exposure time were calculated using the method of Bliss (1952).

Sex:

male

Dose descriptor:

LC50

Effect level:

4 970 ppm

Based on:

test mat.

95% CL:

4 584 - 5 388

Exp. duration:

5 min

Remarks on result:

other: slope: 11.8 std. dev. +/- 4.2

Sex:

male

Dose descriptor:

LC50

Effect level:

2 689 ppm

Based on:

test mat.

95% CL:

2 397 - 3 016

Exp. duration:

15 min

Remarks on result:

other: slope: 9.4 std. dev. +/- 2.1

Sex:

male

Dose descriptor:

LC50

Effect level:

2 042 ppm

Based on:

test mat.

95% CL:

1 901 - 2 192

Exp. duration:

30 min

Remarks on result:

other: slope: 14.0 std. dev. +/- 3.3

Sex:

male

Dose descriptor:

LC50

Effect level:

1 307 ppm

Based on:

test mat.

95% CL:

1 212 - 1 410

Exp. duration:

60 min

Remarks on result:

other: slope: 10.7 std. dev. +/- 3.8

Mortality:

Mortality occurred, but count of rats that passed away was not reported. Some deaths were reported to occur during the post-exposure observation period.

Clinical signs:

other: Conjunctival and nasal irritation as shown by reddened conjunctivae, pawing at the nose, marked lacrimation, nasal secretion and sneezing. These signs were not seen 1 week following exposure (in surviving animals). Respiratory distress and general weaknes

Body weight:

Body weight loss was observed in surviving animals. Compared to controls, surviving rats exhibited a 10-15% reduction in body weight during the first 3-7 days after exposure, after which weights returned to normal.

Gross pathology:

Lesions were found (differing quantitatively from that of controls) in the kidneys, liver, nasal passage, bone marrow and skin of exposed rats.

The LC50 values were 4970, 2690, 2040 and 1310 ppm for rats exposed to hydrogen fluoride vapour for 5, 15, 30 and 60 minutes, respectively.

Interpretation of results:

very toxic

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The LC50 values were 4970, 2690, 2040 and 1310 ppm for rats exposed to hydrogen fluoride vapour for 5, 15, 30 and 60 minutes, respectively.
1310 ppm HF equals 218 ppm WF6 and 2700 mg/m³ of WF6 at 20 °C and 1,013 bar

Executive summary:

Male Wistar rats were exposed to lethal concentrations of hydrogen fluoride vapour, at various concentrations for either 5, 15, 30 or 60 minutes. The LC50 values were 4970, 2690, 2040 and 1310 ppm for rats exposed to hydrogen fluoride vapour for 5, 15, 30 and 60 minutes, respectively. Exposure resulted in mortalities, although numbers and times of death are not reported. Lesions were observed in the kidneys, liver, nasal passages, bone marrow and skin. Exposure resulted in conjunctival and nasal irritation, respiratory distress and general weakness and body weight loss.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

2 700 mg/m³ air

Quality of whole database:

This studay supported by other inhalation exposure studies and therefore considered as valid. HF has been examined by several laboratories over the last decades and published/well accepted LC50 values are in a very narrow range. The most conservative LC50 value was chosen.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Justification for selection of acute toxicity – oral endpoint
Study scientifically unjustified, substance is classified as highly corrosive.

Justification for selection of acute toxicity – inhalation endpoint
WF6 is rapidly hydrolizing into HF at ambient and physiological conditions. Reading accross to studies on HF, following judgedement is resulting:
The most conservative acute 60 minute inhalation toxicity value for HF was reported to be at 1310 ppm. 1310 ppm HF equals 218 ppm WF6 and 2700 mg/m³ of WF6 at 20 °C and 1,013 bar

Justification for classification or non-classification

According to the UN Globally Harmonized System of Classification and Labelling of Chemicals (GHS) Part 3 WF6 is considered to be acute toxic by inhalation: Category 2