Tungsten hexafluoride

Endpoint summary

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

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

Adequacy of study:

key study

Study period:

1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The EU RAR contains a review and summary of available data on HF. The studies compiled in this report were assessed as part of the EU RAR and are therefore considered to be suitably reliable. The same test was reviewed and assessed in a SCIENCE REPORT by the UK Environment Agency and also considered as reliable. Test done under GLP conditions. Read across justification is given in section 13 assessment reports: WF6 justification for read across

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

Principles of method if other than guideline:

In a range-finding study, groups of five male and five female Fischer 344 rats were exposed to measured concentrations of 0, 1, 10, 25, 65 or 100 ppm (0, 0.83, 8.3, 21, 54 and 83 mg/m3) for 6 hours/day, 5 days/week, for 2 weeks; survivors were sacrificed 2 days later. 10 exposures within 15 days.

GLP compliance:

not specified

Remarks:

As per EU RAR on HF study reported to be GLP complaint.

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Route of administration:

inhalation: gas

Type of inhalation exposure:

not specified

Vehicle:

air

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

6 hours

Frequency of treatment:

5 days/week for 2 weeks

Remarks:

Doses / Concentrations:
1 ppm (0,83 mg/m³)
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
10 ppm (8,3 mg/m³)
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
25 ppm (21 mg/m³)
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
65 ppm (54 mg/m³)
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
100 ppm (83 mg/m³)
Basis:
analytical conc.

No. of animals per sex per dose:

five male and five female

Control animals:

yes

Dose descriptor:

NOAEL

Effect level:

1 ppm (analytical)

Based on:

test mat.

Sex:

male/female

Dose descriptor:

NOAEL

Effect level:

0.83 mg/m³ air (analytical)

Based on:

test mat.

Sex:

male/female

Critical effects observed:

not specified

Conclusions:

NOAEL for HF is 1 ppm which equals 0.17 ppm of WF6 and 2.1 mg/m³ WF6 at 20 °C and 1,013 bar.

Executive summary:

In a range-finding study, groups of five male and five female Fischer 344 rats were exposed to measured concentrations of 0, 1, 10, 25, 65 or 100 ppm (0, 0.83, 8.3, 21, 54 and 83 mg/m³) for 6 hours/day, 5 days/week, for 2 weeks; survivors were sacrificed 2 days later (Placke et al, 1990). Exposures to 25 ppm (21 mg/m³) and above resulted in deaths of all females, with deaths beginning on the eighth, third, and second day of exposure at the 25, 65, and 100 ppm (21, 54 and 83 mg/m³) concentrations, respectively. Exposures to 65 and 100 ppm (54 and 83 mg/m³) resulted in deaths of all males, with deaths beginning on the third and second day at the 65 and 100 ppm concentrations, respectively. No deaths occurred during the first day of exposure at any concentration, and no deaths occurred at the lower concentrations.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

2.1 mg/m³

Study duration:

subacute

Species:

rat

Quality of whole database:

Since WF6 is hydrolising rapidly to HF under ambient and physiological conditions, read across to studies on HF and NaF was done. It is turning out that the fluoride anion is inducing adverse effects, while the effect of the sodium kation or proton (Na+ or H+) is negigible. Tungsten oxides are not considered as dangerous/toxic. So, the read across data are the best possible approach to describe the properties of WF6 and its hydrolisation products.

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
Most recent study under GLP conditions.

Justification for classification or non-classification

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