Hydrogen fluoride

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1987-06-23

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

Version / remarks:

1986

GLP compliance:

no

Specific details on test material used for the study:

Sodium fluoride (termed Natriumfluorid in the test report)

Analytical monitoring:

no

Remarks:

(confirmatory analysis of exposure concentrations is not a requirement of the test method)

Details on sampling:

Not relevant

Vehicle:

no

Remarks:

Appropriate quantities of the test substance were weighed directly into the corresponding test vessels.

Test organisms (species):

activated sludge

Details on inoculum:

The activated sludge inoculum was obtained from a 3L laboratory simulation unit. The report does not state whether the unit was fed with settled domestic or synthetic sewage. The dry sludge solids concentration of the inoculum was 6 g/L and the inoculum was added in 25 mL aliquots to give a dry solids concentration of 600 mg/L in the final working volume of 250 mL in each of the biotic test vessels. The inoculum was withheld from a single vessel at the highest test substance concentration and served as an abiotic control against auto-oxidation.

Test type:

static

Water media type:

other: synthetic sewage prepared according to ISO 8192-1886 (E), section 4.2

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

After the 3h exposure and aeration phase, oxygen consumption was measured during intervals of between 1.0 and 10 minutes, depending on the rate of decline.

Hardness:

Not reported. Hardness was a function of the mineral composition of the synthetic sewage used in the test.

Test temperature:

20.4 to 21.4°C

pH:

7.9 to 8.3

Dissolved oxygen:

2.40 to 8.70 mg O2/L (at the start of respiration rate measurements)

Salinity:

Not relevant

Conductivity:

Not reported

Nominal and measured concentrations:

The nominal test substance concentrations were 0 (control), 1000, 1800, 3200, 5600 and 10000 mg NaF/L.

Details on test conditions:

3 hour incubation with activated sludge

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (3,5-DCP)

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

2 930 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: Equivalent to 1324 mg F/L.

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

1 127 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: Equivalent to 510 mg F/L

Details on results:

An EC10 of 1127 mg NaF/L is reported, equivalent to 509 mg fluoride/L.

Results with reference substance (positive control):

0% inhibition at 1 mg 3,5-DCP/L
75% inhibition at 20 mg 3,5-DCP/L

Reported statistics and error estimates:

The following values were determined by probit analysis:
EC05: 859 mg NaF/L (95% CL: 365 - 1289 mg NaF/L)
EC10: 1127 mg NaF/L (95% CL: 562 - 1586 mg NaF/L)
EC50: 2930 mg NaF/L (95% CL: 2270 - 3715 mg NaF/L)
EC90: 7620 mg NaF/L (95% CL: 5532 - 14444 mg NaF/L)
EC95: 9993 mg NaF/L (95% CL: 6821 - 22165 mg NaF/L)

0%, 37.5%, 50.0%, 75.0% and 100% respiration inhibition was recorded at nominal concentrations of 1000, 1800, 3200, 5600 and 10000 mg NaF/L, respectively. 

Validity criteria fulfilled:

yes

Conclusions:

An EC10 of 1127 mg NaF/L (510 mg fluoride-equivalent/L) is reported in a guideline-compliant ASRIT.

Executive summary:

In an activated sludge respiration inhibition study performed according to ISO 8192-1986 (E) (analogous to OECD 209), the 3h EC10 of sodium fluoride was 1127 mg/L, equivalent to 510 mg fluoride/L.

Reference 2

Endpoint:

toxicity to microorganisms, other

Remarks:

Various endpoints investigating toxicity to microorganisms

Type of information:

other: review

Adequacy of study:

weight of evidence

Study period:

16 to 72 hours

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

The EU RAR summarises and reviews the available data on the toxicity of fluoride to aquatic microorganisms. 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 suitabley reliable.

Qualifier:

no guideline followed

Principles of method if other than guideline:

The EU RAR summairses a number of non-Guideline studies

GLP compliance:

no

Analytical monitoring:

not specified

Test organisms (species):

other: various

Test type:

static

Water media type:

freshwater

Remarks on exposure duration:

see details

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

83 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Chilomonas paramaecium

Remarks:

(Bringmann and Kühn, 1981)

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

101 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Entosiphon sulcatum

Remarks:

(Bringmann and Kühn, 1981)

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

180 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: inhibition of acid formation from glucose

Remarks on result:

other: Eschericia coli

Remarks:

(Bringmann and Kühn, 1981)

Duration:

20 h

Dose descriptor:

NOEC

Effect conc.:

7.1 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Uronema parduczi

Remarks:

(Bringmann and Kühn, 1981)

Duration:

28 h

Dose descriptor:

NOEC

Effect conc.:

226 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: Inhibition of feed uptake

Remarks on result:

other: Microregma heterotoma

Remarks:

(Bringmann and Kühn, 1981)

Duration:

16 h

Dose descriptor:

NOEC

Effect conc.:

231 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Pseudomonas putida

Remarks:

(Bringmann and Kühn, 1981)

The EU RAR reports NOEC values of between 7.1 -226 mg/L.

Validity criteria fulfilled:

not specified

Conclusions:

NOEC values of between 7.1 -226 mg/L are reported.

Executive summary:

The EU RAR summarises and reviews the available data on the toxicity of fluoride to aquatic microorganisms; NOEC values of between 7.1 -226 mg/L are reported.

Reference 3

Endpoint:

toxicity to microorganisms, other

Remarks:

Various endpoints investigating toxicity to microorganisms

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

It is considered appropriate to address the toxicity to microorganisms data requirement for hydrogen fluoride (HF) by read-across to available data on sodium fluoride (NaF).

In water, HF (as hydrofluoric acid when in water) dissociates rapidly to form hydrogen (H+) and fluoride (F−) ions, whereas NaF (the highly soluble sodium salt of fluoride) will be fully hydrated in water as separate sodium (Na+) and F- ions. Both HF and NaF (as well as other fluorides) will therefore dissociate rapidly to form F- ions in the aquatic environment, with any effects observed being directly attributable to the F- ion. The Na+ ion is naturally occurring and regulated by organisms (i.e. by homeostatic mechanisms) and consequently is not considered to have an impact on the read-across of ecotoxicological data. On this basis, the profile of HF is comparable to that of NaF with respect to the environment.

Reason / purpose for cross-reference:

read-across source

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

83 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Chlomonas paramaecium

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

101 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Entosiphon sulcatum

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

180 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: inhibition of acid formation from glucose

Remarks on result:

other: Eschericia coli

Duration:

20 h

Dose descriptor:

NOEC

Effect conc.:

7.1 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Uronema parduczi

Duration:

28 h

Dose descriptor:

NOEC

Effect conc.:

226 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: Inhibition of feed uptake

Remarks on result:

other: Microregma heterotoma

Duration:

16 h

Dose descriptor:

NOEC

Effect conc.:

231 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Pseudomonas putida

The EU RAR reports NOEC values of between 7.1 -226 mg/L.

Validity criteria fulfilled:

not specified

Conclusions:

NOEC values of between 7.1 -226 mg/L are reported.

Executive summary:

It is considered appropriate to address the toxicity to microorganisms data requirement for hydrogen fluoride (HF) by read-across to available data on sodium fluoride (NaF). In water, HF (as hydrofluoric acid when in water) dissociates rapidly to form hydrogen (H⁺) and fluoride (F⁻) ions, whereas NaF (the highly soluble sodium salt of fluoride) will be fully hydrated in water as separate sodium (Na⁺) and F^- ions. Both HF and NaF (as well as other fluorides) will therefore dissociate rapidly to form F^- ions in the aquatic environment, with any effects observed being directly attributable to the F^- ion. The Na⁺ ion is naturally occurring and regulated by organisms (i.e. by homeostatic mechanisms) and consequently is not considered to have an impact on the read-across of ecotoxicological data. On this basis, the profile of HF is comparable to that of NaF with respect to the environment.

The EU RAR summarises and reviews the available data on the toxicity of fluoride to aquatic microorganisms; NOEC values of between 7.1 -226 mg/L are reported.

Reference 4

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

It is considered appropriate to address the toxicity to microorganisms data requirement for hydrogen fluoride (HF) by read-across to available data on sodium fluoride (NaF).

In water, HF (as hydrofluoric acid when in water) dissociates rapidly to form hydrogen (H+) and fluoride (F−) ions, whereas NaF (the highly soluble sodium salt of fluoride) will be fully hydrated in water as separate sodium (Na+) and F- ions. Both HF and NaF (as well as other fluorides) will therefore dissociate rapidly to form F- ions in the aquatic environment, with any effects observed being directly attributable to the F- ion. The Na+ ion is naturally occurring and regulated by organisms (i.e. by homeostatic mechanisms) and consequently is not considered to have an impact on the read-across of ecotoxicological data. On this basis, the profile of HF is comparable to that of NaF with respect to the environment.

Reason / purpose for cross-reference:

read-across source

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

2 930 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: Equivalent to 1324 mg F/L.

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

1 127 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: Equivalent to 510 mg F/L

Details on results:

An EC10 of 1127 mg NaF/L is reported, equivalent to 509 mg fluoride/L.

Results with reference substance (positive control):

0% inhibition at 1 mg 3,5-DCP/L
75% inhibition at 20 mg 3,5-DCP/L

Reported statistics and error estimates:

The following values were determined by probit analysis:
EC05: 859 mg NaF/L (95% CL: 365 - 1289 mg NaF/L)
EC10: 1127 mg NaF/L (95% CL: 562 - 1586 mg NaF/L)
EC50: 2930 mg NaF/L (95% CL: 2270 - 3715 mg NaF/L)
EC90: 7620 mg NaF/L (95% CL: 5532 - 14444 mg NaF/L)
EC95: 9993 mg NaF/L (95% CL: 6821 - 22165 mg NaF/L)

0%, 37.5%, 50.0%, 75.0% and 100% respiration inhibition was recorded at nominal concentrations of 1000, 1800, 3200, 5600 and 10000 mg NaF/L, respectively. 

Validity criteria fulfilled:

yes

Conclusions:

An EC10 of 1127 mg NaF/L (510 mg fluoride-equivalent/L) is reported in a guideline-compliant ASRIT.

Executive summary:

It is considered appropriate to address the toxicity to microorganisms data requirement for hydrogen fluoride (HF) by read-across to available data on sodium fluoride (NaF). In water, HF (as hydrofluoric acid when in water) dissociates rapidly to form hydrogen (H⁺) and fluoride (F⁻) ions, whereas NaF (the highly soluble sodium salt of fluoride) will be fully hydrated in water as separate sodium (Na⁺) and F^- ions. Both HF and NaF (as well as other fluorides) will therefore dissociate rapidly to form F^- ions in the aquatic environment, with any effects observed being directly attributable to the F^-ion. The Na⁺ ion is naturally occurring and regulated by organisms (i.e. by homeostatic mechanisms) and consequently is not considered to have an impact on the read-across of ecotoxicological data. On this basis, the profile of HF is comparable to that of NaF with respect to the environment.

In an activated sludge respiration inhibition study performed according to ISO 8192-1986 (E) (analogous to OECD 209), the 3h EC10 of sodium fluoride was 1127 mg/L, equivalent to 510 mg fluoride/L.

Description of key information

In an activated sludge respiration inhibition study performed according to ISO 8192-1986 (E) (analogous to OECD 209), the 3h EC10 and EC50 of sodium fluoride were 1127 mg/L and 2930 mg/L respectively, equivalent to 510 and 1324 mg fluoride/L.  A number of supporting studies are reported in the EU RAR. 

Key value for chemical safety assessment

EC50 for microorganisms:

1 324 mg/L

EC10 or NOEC for microorganisms:

510 mg/L

Additional information

In an activated sludge respiration inhibition study performed according to ISO 8192-1986 (E) (analogous to OECD 209), the 3h EC10 and EC50 of sodium fluoride were 1127 mg/L and 2930 mg/L respectively, equivalent to 510 and 1324 mg fluoride/L. The EU RAR summarises and reviews the other available data on the toxicity of fluoride to aquatic microorganisms; NOEC values of between 7.1 -226 mg/L are reported.