Lithium hexafluorophosphate(1-)

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-term toxicity to aquatic invertebrates

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: Results reviewed in an authoritative expert review document and used for risk assessment

Justification for type of information:

Part of weight-of-evidence approach adapting the information requirements of Annex IX 9.1.5 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 The release of HF occurs within 4 seconds in water (Unpublished stability and degradation report, 2011). Subsequently, the lithium fluoride hydrolysis product will dissociate, releasing F- ions. Hence the long-term toxicity of LiPF6 to aquatic 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 long-term environmental toxicity of LiPF6 without the performance of new tests.

Principles of method if other than guideline:

21-day reproduction studies using Daphnia magna: two separately reported studies (Janssen et al 1989 and Kuhn et al 1988)

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:

yes

Details on sampling:

Samples were analysed only in the second of two reported studies (Kuhn et al)

Test organisms (species):

Daphnia magna

Test type:

not specified

Total exposure duration:

21 d

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

3.7 mg/L

Nominal / measured:

nominal

Conc. based on:

other: fluoride concentration

Basis for effect:

reproduction

Remarks on result:

other: Janssen et al paper

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

14.1 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: fluoride concentration

Basis for effect:

reproduction

Remarks on result:

other: Kuhn et al paper

A NOEC value of 8.9 mg F-/l (calculated as the mean across the two reviewed studies) was taken forward for use in PNEC determination in the EU RAR document

Conclusions:

Long-term toxicity of fluoride to Daphnia magna was shown to be low. The lowest reported NOEC (3.7 mg F-/l) corresponds to an LiPF6 concentration of 4.9 mg/l, based on complete F- release

Reference 2

Endpoint:

long-term toxicity to aquatic invertebrates

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: Authoritative international expert review of published data

Justification for type of information:

Part of weight-of-evidence approach adapting the information requirements of Annex IX 9.1.5 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). Subsequently, the lithium fluoride hydrolysis product will dissociate, releasing F- ions. Hence the long-term toxicity of LiPF6 to aquatic 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 long-term environmental toxicity of LiPF6 without the performance of new tests.

Principles of method if other than guideline:

21-day toxicity and reproduction studies using Daphnia magna: two separately reported studies (Fieser et al, 1986; Dave, 1984)

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:

yes

Details on sampling:

Samples analysed at each change of test medium (Fieser et al). No information regarding possible analysis (Dave).

Test organisms (species):

Daphnia magna

Test type:

other: Semi-static (Fieser et al). No data (Dave)

Total exposure duration:

21 d

Duration:

3 wk

Dose descriptor:

NOEC

Effect conc.:

26 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: fluoride

Basis for effect:

other: adverse effect on reproduction

Remarks on result:

other: Neonate numbers 445 of control group at 35 mg F-/l; near-complete (98%) inhibition of live progeny production at 49 mg F-/l (Fieser et al, 1986)

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

> 3.7 - < 7.4 mg/L

Nominal / measured:

not specified

Conc. based on:

other: mg F-/l

Basis for effect:

reproduction

Remarks on result:

other: NOEC based on growth also between 3.7 and 7.4 mg F-/l. A "safe concentration" (geometric mean of NOEC/MATC in hard water) of 4.4 mg/l was calculated (Dave, 1984)

Conclusions:

Low long-term toxicity of fluoride to Daphnia magna was shown

Reference 3

Endpoint:

long-term toxicity to aquatic invertebrates

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 study of Daphnia population changes following eutrophication, published in a peer-reviewed journal

Justification for type of information:

Part of weight-of-evidence approach adapting the information requirements of Annex IX 9.1.5 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). Subsequently, the lithium fluoride hydrolysis product will dissociate, releasing F- ions. Hence the long-term toxicity of LiPF6 to aquatic 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 long-term environmental toxicity of LiPF6 without the performance of new tests.

Principles of method if other than guideline:

Detailed analysis of long-term Daphnia population monitoring in Lake Constance, covering oligotrophic, mesotrophic and meso/eutrophic periods

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Phosphate, PO4(3-) is a hydrolysis product formed by the reaction of LiPF6 with water

Analytical monitoring:

yes

Details on test solutions:

Waters of Lake Constance

Test organisms (species):

Daphnia sp.

Test type:

other: Regular sampling of daphnid populations in Lake Constance over 3 periods: 5 years 1920-1924, 10 years 1952-1962, 17 years 1979-1995

Water media type:

freshwater

Remarks on exposure duration:

Daphnid population data recorded during 32 years of population monitoring: data collected during 3 sampling periods spread across a total of 75 years

Details on test conditions:

Lake Constance is a large and deep lake in the temperate zone of Europe

Remarks on result:

not determinable

Remarks:

Not a standard long-term invertable study, see "any other information on results" section for more details

Details on results:

Eutrophication of Lake Constance in the years following sampling period 1 (1920-1924) was associated with a marked (circa 30-fold) increase in daphnid population (biomass) seen during sampling period 2 (1952-1962). This increase was evident throughout each year of sampling.
Comparison of daphnid population (biomass) data for sampling period 3 (1979-1995) with that for sampling period 2 showed little or no increase in the first 5 months of each annual period, and a circa 6-fold increase in each June - October period (postulated to reflect lakewater stratification from late Spring into the Autumn). The two later sampling periods both covered years when total phosphorus levels were high compared to the initial, oligotrophic status of Lake Constance during sampling period 1.
During the 17 years of sampling period 3, total phosphorus concentrations declined steadily, falling from 87 to 24 microgrammes/l. During this period, neither annual mean data for daphnid biomass nor the (typically higher) annual values for July-December biomass showed any clear pattern of increase or decrease.

The change in lake status from oligotrophic (1920 -1924) to eutrophic (1952 -1962) due to phosphate inputs was associated with an approximately 30 -fold increase in daphnid population.

Conclusions:

Long-term measurement of daphnid populations in a major European freshwater lake showed a marked increase in population (total biomass) associated with increased phosphorus concentrations (input of phosphate). The authors noted compatibility of their findings (increased daphnid biomass with eutrophication) with those reported for several other lakes by other researchers. Later reduction of Lake Constance phosphorus levels did not not clearly affect daphnid population size.
Overall, only indications of a beneficial effect of phosphate input on daphnid population were reported: no evidence of adverse effects of phosphate input were seen.

Reference 4

Endpoint:

long-term toxicity to aquatic invertebrates

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 9.1.5 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). Subsequently, the lithium fluoride hydrolysis product will dissociate, releasing F- ions. Hence the long-term toxicity of LiPF6 to aquatic 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 long-term environmental toxicity of LiPF6 without the performance of new tests.

Qualifier:

according to guideline

Guideline:

other: EPA/600/4-91/002

Principles of method if other than guideline:

Determination of effects of lithium of survival and reproduction of Ceriodaphnia dubia

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Li+ is a hydrolysis product of LiPF6 (which reacts rapidly on contact with water)

Analytical monitoring:

yes

Details on test solutions:

River water or dilute mineral water used for test dilutions: differing sodium contents measured

Test organisms (species):

Ceriodaphnia dubia

Test type:

semi-static

Total exposure duration:

7 d

Nominal and measured concentrations:

Measured Li+ concentrations across test groups ranged from 0.2 to 6.05 mg/l

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

2.55 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: Li+ concentration

Basis for effect:

reproduction

Remarks on result:

other: Independent of sodium concentration across the tested range 11-110 mg Na+/l

Details on results:

In water with a very low sodium content (1.7 mg/l), exposure to 1 mg Li+/l proved lethal within 6 days, but with 40 mg Na/l 100% survival was seen at 4 mg Li+/l. Exposure to lithium at concentrations up to 2.55 mg Li+/l had no significant effect on reproduction, in tests run at Na concentrations from 11 to 110 mg/l.

Conclusions:

A NOEC value for Ceriodaphnia dubia reproduction of 2.55 mg Li+/l was determined in tests where sodium concentrations relevant to environmental conditions were employed.

Reference 5

Endpoint:

long-term toxicity to aquatic invertebrates

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: Result of Japanese Ministry sponsored test programme, reported online.

Justification for type of information:

Part of weight-of-evidence approach adapting the information requirements of Annex IX 9.1.5 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). Subsequently, the lithium fluoride hydrolysis product will dissociate, releasing F- ions. Hence the long-term toxicity of LiPF6 to aquatic 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 long-term environmental toxicity of LiPF6 without the performance of new tests.

Qualifier:

according to guideline

Guideline:

other: OECD guideline 202

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Li+ is a product of the hydrolysis reaction of LiPF6 with water

Test organisms (species):

Daphnia magna

Test type:

not specified

Total exposure duration:

21 d

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

29 mg/L

Conc. based on:

test mat.

Basis for effect:

reproduction

Conclusions:

The reported NOEC for lithium bromide of 10 mg/l is equivalent (in terms of Li+ concentration) to 17.5 mg LiPF6/l

Description of key information

Given the hydrolytic instability of LiPF6, long-term toxicity to aquatic organisms is best defined in terms of the toxicity of its F-, Li+ and PO4(3 -) hydrolysis products as a weight-of-evidence approach.  Review of the known toxicities of these leads to a clear conclusion that the fluoride released from LiPF6 is the “toxic marker” for long-term toxicity to invertebrates: from the lowest reported fluoride 21-day Daphnia NOEC of 3.7 mg F-/l a long-term NOEC value of 4.9 mg LiPF6/l is calculated (based on the expected complete F- release).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

4.9 mg/L

Additional information

HF

In the aquatic environment, HF will principally be present in the form of fluoride ion. For this reason, test data obtained using soluble inorganic fluorides can be used to evaluate HF toxicity and EC50 or NOEC values expressed in terms of mg F-/l are appropriate for assessment of HF toxicity to aquatic organisms (HF: EU Risk Assessment Report, 2001).

 

Fluoride

Two different NOEC values in Daphnia 21-day reproduction studies are reported in the HF: EU Risk Assessment Report (2001): 3.7 mg F-/l and 14.1 mg F-/l. In another authoritative review of fluoride toxicity (WHO EHC 227, 2002), two further Daphnia reproduction studies are described: one reported effects on reproduction at concentrations above 26 mg F-/l, but the other presented more detailed findings. NOEC values for Daphnia growth and reproduction from the latter study were calculated to be in the range 3.7 – 7.4 mg F-/l, leading to calculation of 4.4 mg F-/l as a “safe concentration”.

 

Lithium

A series of experiments have been performed investigating the effects of lithium exposure in waters of varying sodium levels on survival and reproduction of Ceriodaphnia dubia (Kzos, Beauchamp and Stewart, 2003). In water with low sodium content (1.7 mg/l), exposure to 1 mg Li+/l proved lethal within 6 days, but with 40 mg Na/l 100% survival was seen at 4 mg Li+/l. Exposure to lithium at concentrations up to 2.55 mg Li+/l had no significant effect on reproduction (except when sodium content was increased to 700 mg/l). In a 21-day Daphnia magna reproduction study with lithium bromide, EC50 and NOEC values of 29 and 10 mg/l were determined (Japan MoE, 2001).

 

Phosphate

Phosphate is widely present in the environment and is naturally present (and necessary) in living organisms. Control of phosphate contamination of surface waters through phosphate discharge or run-off following its use in agriculture or in detergents has been imposed to limit problems of eutrophication, with consequent increase of algal growth, rather than direct toxicity to aquatic organisms.  Long-term measurement of daphnid populations in a major European freshwater lake (Lake Constance) showed a marked increase in population (total biomass) associated with increased phosphorus concentrations (input of phosphate): Straile and Geller, 1998. These authors noted compatibility of their findings (increased daphnid biomass with eutrophication) with those reported for several other lakes by other researchers. Later reduction of Lake Constance phosphorus levels did not clearly affect daphnid population size. Overall, only indications of a beneficial effect of phosphate input on daphnid population were reported: no evidence of adverse effects of phosphate input were seen. There is no reason to suppose that phosphate released from LiPF6 could adversely affect aquatic invertebrates.

 

Key value for assessment

The lowest long-term NOEC value reported for fluoride is 3.7 mg F-/l and the lowest NOEC for lithium is 2.55 mg/l; these values correspond to LiPF6 concentrations of 4.9 and 55.8 respectively.  Due to its low toxicity, the contribution of phosphate to LiPF6 toxicity is considered insignificant. It is therefore concluded that the fluoride released from LiPF6 in water is the “toxic marker” for long-term toxicity to invertebrates and a long-term NOEC value of 4.9 mg/l for LiPF6 is taken for use in assessment.