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Sediment toxicity

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Endpoint:
sediment toxicity: long-term
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
The read-across justification is included in section 13.
Reason / purpose:
read-across source
Key result
Duration:
10 d
Dose descriptor:
other: IC10
Effect conc.:
< 8.42 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
other: growth
Duration:
10 d
Dose descriptor:
other: IC20
Effect conc.:
16.84 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
other: growth
Key result
Duration:
10 d
Dose descriptor:
other: IC50
Effect conc.:
76 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
other: growth
Key result
Duration:
10 d
Dose descriptor:
LC50
Effect conc.:
112.56 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
mortality
Validity criteria fulfilled:
yes
Conclusions:
The sub-chronic (10-d) exposure of larval Chrionomid dilutus to NaF in a sediment toxicity study shows that the IC10 is <4.1 mg/L F- and the LC50 is 54.8 mg/L F-. Using the molecular weight information, this is converts to IC10 <8.42 and LC50 = 112.56 mg/L CaF2.
Executive summary:

A sub-chronic sediment toxicity study has been carried out according to Canadian standards (EPS 1/RM32, test for survival and growth in sediment using larvae of freshwater midges. In this study, Chironomid dilutus was exposed to fluoride spiked water for 10 days and the effect on survival and growth (dry weight) has been assessed. The sediment used was uncontaminated sand from a beach in southern British Colombia, Canada.

The IC10 was <4.1 mg/L F and the LC50 is 54.8 mg/L fluoride.

Using the molecular weight information, this is converts to IC10 <8.42 and LC50 = 112.56 mg/L CaF2.

Endpoint:
sediment toxicity: long-term
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Study period:
2014
Justification for type of information:
The read-across justification is provided in section 13
Reason / purpose:
read-across source
Key result
Duration:
14 d
Dose descriptor:
other: IC10
Effect conc.:
>= 3.7 - <= 10.68 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
other: inhibition
Duration:
14 d
Dose descriptor:
other: IC20
Effect conc.:
>= 5.13 - <= 13.56 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
other: inhibition
Key result
Duration:
14 d
Dose descriptor:
other: IC50
Effect conc.:
>= 8.42 - <= 19.51 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
other: inhibition
Key result
Duration:
14 d
Dose descriptor:
LC50
Effect conc.:
>= 9.86 - <= 26.5 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
mortality

Results chronic study

Cl (mg/L) Hardness (mg/L CaCO3) IC10 (mg/L F) IC20 (mg/L F) IC50 (mg/L F) LC50 (mg/L F)
2 90 1.8 2.5 4.1 4.8
6 88 3.8 4.7 6.5 8.6
18 88 5.2 6.6 9.5 12.9
Validity criteria fulfilled:
yes
Conclusions:
The long-term exposure of Hyalella Azteca in a sediment toxicity study to NaF shows that the IC10 varies between 1.8 and 5.2 mg/L F- (depending on the Cl- concentration) and the LC50 varies between 4.8 and 12.9 mg/L F- (depending on the Cl- concentration).
Converting the LC50 to CaF2 (using the molecular weight info), the LC50 values ranged from to 9.86 to 26.5 mg/L CaF2.
Executive summary:

A chronic sediment toxicity study has been carried out according to Canadian standards (EPS 1/RM33, test for survival and growth in sediment using the freshwater amphipod Hyalella azteca). In this study, Hyalella azteca was exposed to fluoride (NaF) spiked water for 14 days and the effect on survival and growth (dry weight) has been assessed. The sediment used was uncontaminated sand from a beach in southern British Colombia, Canada. The fluoride concentrations tested were 2, 6 and 8 mg/L. The test concentration was confirmed analytically. Simultaneously, the effect of Cl- on fluoride toxicity has been assessed (2, 6 and 18 mg/L Cl-).

If was found that the toxicity of fluoride decreases with increasing chloride concentrations.

The IC10 was 1.8 to 5.2 mg/L F, with the highest IC10 value found at the highest Cl- concentration. The IC50 is 4.1 to 9.5 mg/L F- and the LC50 is 4.8 - 12.9 mg/L fluoride.

Converting the effect values to CaF2, using the molecular weight info, this relates to:

IC10 of 3.7 to 10.68 mg/L CaF2, IC50 of 8.42 to 19.51 mg/L CaF2 and LC50 of 9.786 to 26.5 mg/L CaF2.

Description of key information

Pearcy et al. (2015) assessed the toxicity of NaF to sediment organisms Hyalella azteca and larval Chironomid dilutus. In both (sub-)chronic assessments, the organisms were exposed to spiked water (replaced 3 times per week). The exposure time was 14d and 10d respectively and the study was conducted according to the Canadian Environment standards.

The IC10 (growth) concentrations (converted to CaF2 based on molecular weight) were:

- Hyalella: 3.7 to 10.68 mg/L CaF2 (increasing IC10 with increasing on Cl concentration)

- Chironomid: < 8.42 mg/L CaF2

The LC50 valu(converted to CaF2) were:

- Hyalella: 9.86 - 26.5 mg/L CaF2

- Chironomid: 112.56 mg/L CaF2

The key values could not be expressed in mg/kg sediment.

Key value for chemical safety assessment

Additional information