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Toxicity to terrestrial arthropods

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Endpoint:
toxicity to terrestrial arthropods: long-term
Type of information:
other: Information on major hydrolysis product of the registered substance (released rapidly on contact with water/moisture).
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Study report cited in an authoritative expert review, but lacking experimental detail
Justification for type of information:
Part of weight-of-evidence approach adapting the information requirements of Annex IX 9.4.1 and Annex X 9.4.4 under REACH in accordance with Annex XI Section 1.2. Lithium hexafluorophosphate is reactive and unstable in water and air. Reaction in contact with water proceeds rapidly, with release of hydrogen fluoride (forming hydrofluoric acid). The reaction can be summarised as: LiPF6 + 4H2O → 5HF + LiF + H3PO4 The release of HF occurs within 4 seconds in water (Unpublished stability and degradation report, 2011).  HF dissociates to release F- in water, and subsequently, the lithium fluoride hydrolysis product will dissociate, releasing F- ions. Hence the toxicity of LiPF6 to terrestrial organisms is determined by the toxicities of its hydrolysis products F-, Li+ and PO4(3-). Sufficient data concerning these toxicities are available to allow determination of the environmental toxicity of LiPF6 without the performance of new tests: the available information on toxicity to mammalian and aquatic organisms clearly indicates that fluoride is the most toxic of the hydrolysis products and hence it is appropriate to focus on this to characterise the toxicity of LiPF6 to terrestrial organisms. In accordance with section 2 of REACH Annex XI, adsorption testing of LiPF6 is not technically possible due to its high reactivity and instability.
Principles of method if other than guideline:
Test of long-term toxicity to the woodlouse (non-guideline test method).
GLP compliance:
not specified
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
F- is a product of the rapid reaction of LiPF6 with water
Analytical monitoring:
not specified
Test organisms (species):
Porcellus scaber
Animal group:
Crustacea (soil-dwelling woodlouse)
Total exposure duration:
126 d
Duration:
126 d
Dose descriptor:
NOEC
Effect conc.:
800 other: mg/kg soil (dw or wet wt not specified)
Conc. based on:
other: F- concentration
Basis for effect:
not specified
Remarks on result:
other: Beyer et al 1987

No further information available

Conclusions:
The cited NOEC for NaF (800 mg/kg soil) corresponds to 1066 mg LiPF6/kg (based on complete F- release).
Endpoint:
toxicity to terrestrial arthropods: long-term
Type of information:
other: Information on major hydrolysis product of the registered substance (released rapidly on contact with water/moisture).
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well described report of an experimental study, published in a peer-reviewed journal
Justification for type of information:
Part of weight-of-evidence approach adapting the information requirements of Annex IX 9.4.1 and Annex X 9.4.4 under REACH in accordance with Annex XI Section 1.2. Lithium hexafluorophosphate is reactive and unstable in water and air. Reaction in contact with water proceeds rapidly, with release of hydrogen fluoride (forming hydrofluoric acid). The reaction can be summarised as: LiPF6 + 4H2O → 5HF + LiF + H3PO4 The release of HF occurs within 4 seconds in water (Unpublished stability and degradation report, 2011).  HF dissociates to release F- in water, and subsequently, the lithium fluoride hydrolysis product will dissociate, releasing F- ions. Hence the toxicity of LiPF6 to terrestrial organisms is determined by the toxicities of its hydrolysis products F-, Li+ and PO4(3-). Sufficient data concerning these toxicities are available to allow determination of the environmental toxicity of LiPF6 without the performance of new tests: the available information on toxicity to mammalian and aquatic organisms clearly indicates that fluoride is the most toxic of the hydrolysis products and hence it is appropriate to focus on this to characterise the toxicity of LiPF6 to terrestrial organisms. In accordance with section 2 of REACH Annex XI, adsorption testing of LiPF6 is not technically possible due to its high reactivity and instability.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Investigation of fluoride toxicity to the arthropod Porcellio scaber ina micro-ecosystem with leaf litter substrate
GLP compliance:
not specified
Application method:
other: test substance dissolved in water and mixed with leaf litter substrate
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
F- is a product of the rapid reaction of LiPF6 with water
Analytical monitoring:
yes
Details on sampling:
Litter samples were analysed prior to KF addition, 4 weeks later (prior to woodlouse introduction) and at the end of the experimental period
Details on preparation and application of test substrate:
Poplar leaf litter collected from a Dutch forest was air-dried and cut int small pieces; this was wetted with aqueous KF solution. Water was then evaporated at 20C to give 2.3:1 water:dry material
Test organisms (species):
Porcellus scaber
Animal group:
Crustacea (soil-dwelling woodlouse)
Study type:
extended laboratory study
Total exposure duration:
5 wk
Remarks:
Woodlice were introduced after 4 weeks of microsystem stabilisation and exposed for a total of 5 weeks
Test temperature:
15C
Humidity:
Water content was maintained by wetting of sand (held in a layer below the leaf litter, separated by nylon gauze)
Nominal and measured concentrations:
Nominal test concentrations were 0, 1.7, 5.3, 17, 53, 170 micromol F-/g litter (32 - 3230 mg F-/kg dw litter).
Measured concentrations:
- total F- 1.37 (untreated control), 1.90, 7.53, 17.79, 59.58, 190.00 micromol F-/g (26 - 3610 mg F-/kg dw litter).
- extractable F- 0.15 (untreated control), 1.11, 2.79, 8.42, 10.79, 25.00 micromol F-/g (2.8 - 475 mg F-/kg dw litter).
Reference substance (positive control):
no
Duration:
5 wk
Dose descriptor:
NOEC
Effect conc.:
3 230 other: mg/kg dw substrate
Nominal / measured:
nominal
Conc. based on:
other: fluoride concentration
Basis for effect:
mortality
Conclusions:
Woodlice showed little sensitivity to fluoride, even at high concentration in the tested leaf litter substrate.

Description of key information

A 5-week NOEC value for the woodlouse was determined to be 3230 mg/kg substrate dry weight, using a leaf litter substrate (Van Wensem and Adema, 1991).  This corresponds to an LiPF6 concentration of 4304 mg/kg dry weight. 

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil dwelling arthropods:
3 230 mg/kg soil dw

Additional information

Woodlice showed little sensitivity to fluoride