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Long-term toxicity to fish

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Endpoint:
adult fish: sub(lethal) effects
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study summarised in ICD and EU RAR. Methodologcial data for individual studies are incomplete, however the studies have been assessed as part of the EU RAR and are therefore considered to be suitably reliable.
Justification for type of information:
A read-across justification is provided in section 13.
Reason / purpose:
read-across source
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
8.22 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
In a 21 day test with Oncorhynchus mykiss a LC5 value of 4 mg F-/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water.
Using the information on molecular weight, this corresponds to LC5 of 8.22 mg CaF2/L.
Results with reference substance (positive control):
No results reported.
Reported statistics and error estimates:
No results reported.

In a 21 day test with Oncorhynchus mykiss a LC5 value of 4 mg/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water.

Using the information on molecular weight, this corresponds to LC5 of 8.22 mg CaF2/L.

Conclusions:
In a 21 day test with Oncorhynchus mykiss, the toxicity of NaF was investigated. A LC5 value of 4 mg F-/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water. Using the information on molecular weight, this corresponds to LC5 of 8.21 mg CaF2/L.
Executive summary:

In a 21 day test with Oncorhynchus mykiss, the toxicity of NaF was investigated. A LC5 value of 4 mg F-/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water.

Using the information on molecular weight, this corresponds to LC5 of 8.22 mg CaF2/L.

Endpoint:
fish early-life stage toxicity
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
Read-across justification is attached in section 13.
Reason / purpose:
read-across source
GLP compliance:
yes (incl. certificate)
Key result
Duration:
29 d
Dose descriptor:
LOEC
Effect conc.:
> 9.2 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Remarks:
CaF2
Duration:
29 d
Dose descriptor:
NOEC
Effect conc.:
>= 9.2 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Remarks:
CaF2

Observations:

Measured concentration     Hatchability  average days to hatch morphological abnormality rate  Survival rate at the end of the exposure individual wet body weight individual body length
(mg/L NaF)   N (%) (day) (%) (%) (mg) (cm)
control A 15 100 9,53 0 100 53 1.5
B 15 86.7 9.15 0 100 48 1.5
C 15 93.3 9.29 0 100 55 1.5
D 15 93.3 10.1 0 100 61 1.5
Mean   93.3 9.53 0 100 54 1.5
std dev   5.4 0.44 0 0 13 0.2
0.31 A 15 93.3 9.5 6.7 100 55 1.6
B 15 93.3 9.21 6.7 100 57 1.5
C 15 93.3 8.93 0 92.9 58 1.5
D 15 93.3 9.29 0 92.9 52 1.5
Mean 15 93.3 9.23 3.3 96.4 56 1.5
std dev 15 0 0.24 3.8 4.1 11 0.1
0.59 A 15 93.3 9.71 0 100 62 1.6
B 15 100 9.07 0 86.7 60 1.6
C 15 93.3 9.14 0 92.9 59 1.5
D 15 93.3 9 0 92.9 59 1.5
Mean   95 9.23 0 93.1 60 1.6
std dev   3.3 0.33 0 5.5 11 0.1
1.2 A 15 93.3 9.14 0 92.9 55 1.5
B 15 86.7 9 0 84.6 46 1.4
C 15 80 9 0 100 48 1.5
D 15 80 8.85 0 100 54 1.5
Mean   83.3 9 0 94.4 51 1.5
std dev   11.5 0.12 0 7.3 11 0.1
2.3 A 15 93.3 9.5 0 92.9 55 1.5
B 15 86.7 9.23 0 92.3 58 1.5
C 15 80 9.25 0 100 51 1.5
D 15 80 9 0 91.7 54 1.5
Mean   85 9.25 0 94.2 54 1.5
std dev   6.4 0.2 0 3.9 16 0.1
4.7 A 15 100 9.53 0 100 55 1.5
B 15 86.7 9.31 0 92.3 53 1.5
C 15 93.3 9.29 0 100 53 1.5
D 15 100 9.4 0 93.3 51 1.5
Mean   95 9.38 0 96.4 53 1.5
std dev   6.4 0.11 0 4.2 11 0.1
Validity criteria fulfilled:
not specified
Conclusions:
The NOEC value in the FELS study is ≥ 9.9 mg/L NaF (arithmetic mean). Using the molecular weight information, this is converted to a NOEC of ≥ 9.2 mg/L CaF2.
Executive summary:

The Ministry of Environment in Japan conducted a OECD 210. Fish were administered NaF in the range of 0 to 10 mg/L NaF and a spacing factor 2. The LOEC and NOEC were determined to be > 9.9 and ≥ 9.9 mg NaF/L(measured, arithmetic) respectively. Using the molecular weight information, this is converted to a NOEC of ≥ 9.2 mg/L CaF2.

Endpoint:
long-term toxicity to fish, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
Read-across justification is provided in Section 13
Reason / purpose:
read-across source
Duration:
7 d
Dose descriptor:
IC10
Effect conc.:
>= 38 - <= 159 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
weight
Remarks on result:
other: P. promelas, fathead minnow
Duration:
7 d
Dose descriptor:
IC50
Effect conc.:
> 131.5 - <= 259 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
weight
Remarks on result:
other: P. promelas, fathead minnow
Duration:
7 d
Dose descriptor:
LC50
Effect conc.:
> 146 - <= 273 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
mortality
Remarks on result:
other: P. promelas, fathead minnow
Duration:
7 d
Dose descriptor:
IC10
Effect conc.:
>= 11.9 - <= 44.4 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
weight
Remarks on result:
other: O. mykiss, rainbow trout
Duration:
7 d
Dose descriptor:
IC50
Effect conc.:
> 131.5 - <= 259 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
weight
Remarks on result:
other: O. mykiss, rainbow trout
Duration:
7 d
Dose descriptor:
LC50
Effect conc.:
>= 23.6 - <= 84 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
mortality
Remarks on result:
other: O. mykiss, rainbow trout
Duration:
17 d
Dose descriptor:
IC50
Effect conc.:
> 275 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
larval development
Remarks:
embryo development
Remarks on result:
other: S. namacycush, lake trout
Duration:
17 d
Dose descriptor:
LC50
Effect conc.:
> 275 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
mortality
Remarks on result:
other: S. namacycush, lake trout
Duration:
17 d
Dose descriptor:
IC10
Effect conc.:
> 275 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: embryo survival
Remarks on result:
other: S. namacycush, lake trout
Details on results:
The most sensitive fish is the rainbow trout. Lake trout was insensitive to fluoride. However this difference between both species could be attributed to different life-stages in the study: the lake trout test involved an exposure of the developping eggs, while the rainbow trout test was conducted using swim-up fry.
Results of the study indicate that chloride acts as a major toxicity modifying factor for fluoride for some species, but not to others, suggesting that there may be differing uptake pathways between species.
Results with reference substance (positive control):
The toxicity tests met the criteria for acceptable control performance.

Analytical results fluoride:

Measurement of fluoride were in good agreement with target concentrations: (101 +/- 9%) of target. Fluoride levels measured at test termination were 96 +/- 10% of the concentration at test start.

Validity criteria fulfilled:
yes
Conclusions:
Chronic toxicity tests were performed to assess the effect of chloride and water hardness on the fluoride toxicity. The most sensitive fish is the rainbow trout. Lake trout was insensitive to fluoride. However this difference between both species could be attributed to different life-stages in the study. The LC 50 values in F- and as CaF2 for the different species were:
Rainbow trout: 11.5 to 40.9 mg/L F (increase in LC50 with increase in Cl content) - 23.6 to 84 mg/L CaF2
Fathead minnow: > 71.1 to 133 mg/L F (increase in LC50 with increase in Cl content) - 146 to 273 mg/L CaF2
Lake trout embryo: > 134 mg/L F - > 275 mg/L CaF2
Executive summary:

Chronic toxicity tests were performed to assess the effect of chloride and water hardness on the fluoride toxicity. 3 fish species were assessed: rainbow trout (Oncorhynchus mykiss), fathead minnow (Pimephales promelas), lake trout (Salvelinus namacycush). The first two species were assessed in a 7 -d study and effects on survival and growth were recorded. The embryo viability of lake trout was assessed in a 17 -d study.

The most sensitive fish is the rainbow trout. Lake trout was insensitive to fluoride. However this difference between both species could be attributed to different life-stages in the study: the lake trout test involved an exposure of the developping eggs, while the rainbow trout test was conducted using swim-up fry. The LC 50 values for the different species were:

Rainbow trout: 11.5 to 40.9 mg/L F (increase in LC50 with increase in Cl content)

Fathead minnow: > 71.1 to 133 mg/L F (increase in LC50 with increase in Cl content)

Lake trout embryo: > 134 mg/L F

Results of the study indicate that chloride acts as a major toxicity modifying factor for fluoride for some species, but not to others, suggesting that there may be differing uptake pathways between species.

Since fluoride is driving the toxicity of CaF2, read-across to CaF2 is possible. Using the molecular weight information the following LC50 values can be derived:

Rainbow trout: 23.6 to 84 mg/L CaF2

Fathead minnow: 146 to 273 mg/L CaF2

Lake trout embryo: > 275 mg/L CaF2

Description of key information

No studies are available for calcium fluoride. Available studies on NaF were used as read-across source.

The chosen key value was the lowest reported NOEC, among the available studies, in a 29 days test J-check 2010 study with NaF andOryzias latipes. The LOEC and NOEC are ≥ 9.9 mg/L NaF (the highest test concentration) which related to >9.2 mg/L CaF2.

RAR, ICD 1989 reported as well a 21 day test inOncorhynchus mykissperformed with sodium fluoride with a lower LC5 value of 4 mg/L for NaF, equal 8.22 mg/L CaF2, however the study was performed in very soft water, so the effective concentration could not be regarded as key value.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater fish:
9.2 mg/L

Additional information

A weight of evidence approach has been used to evaluate the long-term toxicity to fish. A number of studies have been performed with the water-soluble salt, sodium fluoride and so toxicity of CaF2 was assessed using a read-across method for analogue substance. Effective concentrations were recalculated taking in account the different molecular weight of the source and target substance.

Pearcy et al. (2015) investigated the effect of chloride and water hardness on the fluoride toxicity. The study shows a decrease in toxicity of fluoride with increasing chloride content, hence chloride is a major modifying factor. This study confirms that toxicity results should be considered together with information on the water quality.