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Short-term toxicity to fish

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Endpoint:
short-term toxicity to fish
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: Detailed report of experimental work, published in a peer-reviewed journal
Justification for type of information:
Part of weight-of-evidence approach. 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 The release of HF occurs within 4 seconds in water (Unpublished stability and degradation report, 2011).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 toxicity of LiPF6 to aquatic organisms is determined by the toxicities of its hydrolysis products F-, Li+ and PO4(3-).
Principles of method if other than guideline:
Twelve groups of rainbow trout were fed a basal diet. Each groups diet was supplement with varying concentration of dibasic sodium phosphate.
Groups monitored for effects on growth, feed intake, concentration of inorganic phosphate in plasma over 53 days
GLP compliance:
not specified
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
PO4(3-) is a hydrolysis product of the reaction of LiPF6 with water
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Test type:
flow-through
Water media type:
freshwater
Total exposure duration:
53 d
Hardness:
Ca concentration ranged from 40-50 mg/L
Test temperature:
16.5-17.5C
Nominal and measured concentrations:
Fish were fed pelleted diet containing 1 - 12 g phosphorus/kg dry matter (prepared by diet supplementation with dibasic sodium phosphate)
Duration:
53 d
Dose descriptor:
LOEC
Effect conc.:
2 other: g/kg
Nominal / measured:
nominal
Conc. based on:
other: g phosphorus/kg dry feed
Basis for effect:
weight
Details on results:
Pelleted feed intake and bodyweights increased with increasing levels of phosphate administration. Bodyweight increases showed a plateau around 3-4 g P/kg dry matter in feed. No adverse effects were reported.
Conclusions:
Direct administration to fish of phosphate in food pellets over a prolonged period caused increased growth without reported adverse effects. This indicates that the acute toxicity of inorganic phosphate must be very low.
Endpoint:
short-term toxicity to fish
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. 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 toxicity of LiPF6 to aquatic organisms is determined by the toxicities of its hydrolysis products F-, Li+ and PO4(3-).
Principles of method if other than guideline:
Rangefinding preliminary study for bioaccumulation test
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 the reaction of LiPF6 with water
Analytical monitoring:
not specified
Test organisms (species):
Oryzias latipes
Test type:
not specified
Total exposure duration:
96 h
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
369 mg/L
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 369 mg LiBr/l corresponds to 29.5 mg Li+/l
Conclusions:
The reported LC50 value (369 mg LiBr/l) corresponds to 29.5 mg Li+/l, the concentration of Li+ available from 646 mg/l LiPF6.
Endpoint:
short-term toxicity to fish
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: Minimal experimental detail; selection appropriate for weight of evidence approach
Justification for type of information:
Part of weight-of-evidence approach. 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 toxicity of LiPF6 to aquatic organisms is determined by the toxicities of its hydrolysis products F-, Li+ and PO4(3-).
Principles of method if other than guideline:
Not described - study referenced within published paper
GLP compliance:
not specified
Analytical monitoring:
yes
Test organisms (species):
Pimephales promelas
Test type:
not specified
Water media type:
freshwater
Total exposure duration:
96 h
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
42 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: lithium
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
13 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: lithium
Conclusions:
The reported NOEC of 13 mg Li+/l corresponds to an LiPF6 concentration of 284 mg/l (based on complete Li+ release).
Endpoint:
short-term toxicity to fish
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 review of fluoride toxicity to fish, etc. by international expert group.
Justification for type of information:
Part of weight-of-evidence approach. 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 toxicity of LiPF6 to aquatic organisms is determined by the toxicities of its hydrolysis products F-, Li+ and PO4(3-).
Principles of method if other than guideline:
Expert review of available information on exposure and toxicity of fluorides to vertebrates (e.g. fish).
GLP compliance:
not specified
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Fluoride is a major hydrolysis product of the rapid reaction of LiPF6 with water.
Analytical monitoring:
not specified
Details on test solutions:
4 studies conducted with different hardness of water
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
Size: 1.8g
Test type:
not specified
Water media type:
freshwater
Total exposure duration:
96 h
Hardness:
Study 1: 17 mg CaCO3/L
Study 2: 49 mg CaCO3/L
Study 3: 182 mg CaCO3/L
Study 4: 385 mg CaCO3/L
Test temperature:
12
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
51 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: fluoride
Basis for effect:
mortality
Remarks on result:
other: Study 1
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
128 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: fluoride
Basis for effect:
mortality
Remarks on result:
other: Study 2
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
140 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: fluoride
Basis for effect:
mortality
Remarks on result:
other: Study 3
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
193 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: fluoride
Basis for effect:
mortality
Remarks on result:
other: Study 4
Endpoint:
short-term toxicity to fish
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: EC expert review, including assessment of environmental impact.
Justification for type of information:
Part of weight-of-evidence approach. 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 toxicity of LiPF6 to aquatic organisms is determined by the toxicities of its hydrolysis products F-, Li+ and PO4(3-).
Principles of method if other than guideline:
Detailed expert review of environmental and health impact of HF
GLP compliance:
not specified
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Fluoride (F-) ions are a known hydrolysis product formed from LiPF6 on contact with water.

HF properties listed in the cited data source:
MP -83C, BP 19.5C at 1013 hPa
Water miscible
Low Kow -1.4
Analytical monitoring:
yes
Test organisms (species):
other: Oncorhynchus mykiss, Salmo Trutta
Details on test organisms:
Study 1 & 2: Onchorhynchus mykiss
Study 3: Salmo Trutta
Test type:
not specified
Water media type:
freshwater
Total exposure duration:
96 h
Hardness:
<25 mg CaCO3/L
Reference substance (positive control):
not specified
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
51 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: fluoride
Basis for effect:
mortality
Remarks on result:
other: Study 1
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
108 mg/L
Nominal / measured:
nominal
Conc. based on:
other: fluoride
Basis for effect:
mortality
Remarks on result:
other: Study 2
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
165 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: fluoride
Basis for effect:
mortality
Remarks on result:
other: Study 3

Description of key information

Given the hydrolytic instability of LiPF6, its toxicity to fish 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  toxicity to aquatic organisms: from the available data on F- toxicity to fish, a 96h LC50 value of 68 mg LiPF6/l is calculated (based on complete F- release.

Key value for chemical safety assessment

LC50 for freshwater fish:
68 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 LC50 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

In freshwater, the presence of calcium carbonate in hard water reduces F- availability and hence toxicity through precipitation of calcium fluoride (HF: EU Risk Assessment Report, 2001; WHO EHC 227, 2002). Tests performed in soft water of hardness ≤25 mg CaCO3/l reported 96h LC50 values ranging from 51-165 mg F-/l (3 studies cited, two using Oncorhynchus mykiss, one Salmo trutta: HF: EU Risk Assessment Report, 2001). Acute fish toxicity tests using waters of different hardness reviewed in EHC 227 showed a clear relationship between 96h LC50 and water hardness. At 17, 49, 182 and 385 mg CaCO3/l, reported rainbow trout LC50 values were 51, 128, 140 and 193 mg F-/l respectively; in other cited studies using the stickleback, reported LC50 values in tests using water with 78, 146 and 300 mg CaCO3/l were 340, 380 and 460 mg F-/l respectively. Toxicity tests with four different marine fish species gave 96h LC50 values in the range >100 to >225 mg F-/l (WHO EHC 227, 2002).

 

Lithium

A 96h LC50 value of 369 mg/l for lithium bromide (corresponding to 29.5 mg Li+/l) has been reported for medaka (Oryzias latipes) by the Japanese Environment Ministry (Japan NITE, 2001). In the fathead minnow, the 96h LC50 and NOEC for lithium have been reported as 42 mg/l and 13 mg/l respectively (study cited by Long, Brown and Woodburn, 1998).

 

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. A study of phosphorus supplementation in rainbow trout over 53 days found no evidence that addition of Na2HPO4 into low-phosphorus basal diet at levels giving up to 10.96 g P/kg dry weight (equivalent to 33.6 g PO4/kg or 50.2 g Na2HPO4/kg) adversely affected growth or survival; indeed, weight gain was increased with phosphate supplementation up to a level of approximately 5 g P/kg in diet (equivalent to 8g PO4/kg) (Rodehutscord, 1996). 

 

Key value for assessment

Given the relative quantities of F-, Li+ and PO4- entering solution after contact of LiPF6 with water (LiPF6 + 4H2O → 5HF + LiF + H3PO4 within seconds, followed by slower dissolution then dissociation of the LiF) and the low toxicity of phosphate to fish, it is appropriate to consider the lowest acute fish toxicity 96h LC50 value for fluoride (51 mg F-/l) as the key value for assessment. Conversion of this to an LiPF6 LC50 value could be based on the rapid hydrolysis equation above (i.e. 1 mole LiPF6 releases 5 moles HF which dissociate to 5 F- ions) or, as a worst-case, could also take account of the slower dissolution and ionisation of the LiF hydrolysis product (i.e. 1 mole LiPF6 releases 6 F- ions): for the purposes of assessment the latter is used, giving an LiPF6 96h LC50 value of 68 mg/l.