Lithium hexafluorophosphate(1-)

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: 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:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well described report of a comprehensive study, published in a peer-reviewed journal.

Principles of method if other than guideline:

Determination of aqueous and sediment-associated fluoride to freshwater benthic organisms of various types.

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Fluoride is a product of the rapid reaction of LiPF6 with water.

Analytical monitoring:

yes

Details on sediment and application:

Sediment taken from Long Point, Lake Erie (routinely used as control sediment in toxicity tests performed by the Canadian National Water Research Institute).
Sodium fluoride was weighed, dissolved in 10 ml dilution water and mixed with wet sediment. This was then mixed with dilution water (water:sediment 4;1 v/v) and allowed to settle before use in testing.

Test organisms (species):

other: Fish: Pimephales promelas (juveniles). Mayfly larvae: Hexagenia limbata. Midge larvae: Chironomus tentans. Amphipods: Hyalella azteca

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

natural sediment

Exposure phase:

total exposure duration

Remarks:

Fish (Pimephales promelas) 21 days. Mayfly larvae (Hexagenia limbata) 21 days. Midge larvae (Chironomus tentans) 10 days. Amphipods (Hyalella azteca) 28 days.

Hardness:

Water hardness 160 mg CaCO3/l

Test temperature:

20C

Details on test conditions:

Sediment/water test systems established in glass jars

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

5 600 mg/kg sediment dw

Nominal / measured:

meas. (not specified)

Conc. based on:

other: fluoride concentration

Basis for effect:

other: growth and survival

Remarks on result:

other: P. promelas

Duration:

21 d

Dose descriptor:

other: IC25

Effect conc.:

1 221.3 mg/kg sediment dw

Nominal / measured:

meas. (not specified)

Conc. based on:

other: fluoride concentration

Basis for effect:

growth rate

Remarks:

(Survival IC25 1652.2 mg/kg sediment dw)

Remarks on result:

other: H. limbata

Duration:

10 d

Dose descriptor:

other: IC25

Effect conc.:

661.4 mg/kg sediment dw

Conc. based on:

other: fluoride concentration

Basis for effect:

growth rate

Remarks on result:

other: C. tentans

Duration:

28 d

Dose descriptor:

other: IC25

Effect conc.:

290.2 mg/kg sediment dw

Conc. based on:

other: fluoride concentration

Basis for effect:

growth rate

Remarks:

(Survival IC25 1114.6 mg/kg sediment dw)

Remarks on result:

other: H. azteca

H. Azteca proved to be the species most sensitive to fluoride toxicity.

Conclusions:

A NOEC value for the most sensitive test species (H. azteca ) can be conservatively calculated as one fifth of the reported IC25 for growth (290.2 mg/kg dw): the thus calculated NOEC of 58 mg F-/kg sediment dw corresponds to an LiPF6 NOEC of 77 mg/kg sediment dw (based on fluoride toxicity following complete F- release).

Description of key information

As in surface waters, LiPF6 itself will not be present in freshwater or marine sediments: rather the F-, Li+ and phosphate ions will be present in the unexpected event of significant LiPF6 release. From the reported data on toxicity to mammalian and aquatic organisms, it is clear that fluoride is the most toxic of the degradation products.  In a study using spiked sediment with fish, mayfly and midge larvae plus amphipods, a lowest NOEC of 58 mg fluoride/kg dry weight was determined.  This corresponds to an LiPF6 NOEC of 77.3 mg/kg sediment dw (based on fluoride toxicity following complete F- release).

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater sediment:

77.3 mg/kg sediment dw

Additional information

Metcalfe-Smith et al (2003) investigated the long-term toxicity of freshwater lake sediment spiked with sodium fluoride to sediment-foraging fish (fathead minnow: 21-day exposure), mayfly and midge larvae (21- and 10-day exposure respectively) and amphipods (Hyalella azteca: 28-day exposure). H. azteca proved to be clearly the most sensitive to fluoride, based on both survival (LC50 1,114 mgF-/kg dry weight) and growth (IC25 290.2 mgF-/kg dry weight): while no NOEC value was reported, it is possible to estimate from the data a NOEC value of 58 mgF-/kg dry weight, conservatively calculated as one fifth of the IC25 for growth. This corresponds to an LiPF6 NOEC of 77.3 mg/kg sediment dw (based on fluoride toxicity following complete F- release).