Lithium 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:

2004-01-28 to 2004-02-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Version / remarks:

May 1988

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

1984

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.6800 (Modified Activated Sludge, Respiration Inhibition Test for Sparingly Soluble Chemicals)

Version / remarks:

1996

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot/batch No.: 0000000162
- Expiration date of the lot/batch: October 2008
- Purity test date: 2003-09-12

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Keep container tightly closed in a dry, well-ventilated place. Do not store near acids.
- Stability under test conditions: Stable under ambient conditions

Analytical monitoring:

no

Details on sampling:

Just before the start of the test defined amounts of the test item were directly weighed into each test flask.
The test concentrations (10, 32, 100, 320 and 1000 mg/L) were chosen to permit the determination of the EC 50. Concentrations in excess of nominal 1000 mg test item/L were not tested.

Vehicle:

no

Details on test solutions:

Just before the start of the test defined amounts of the test item were directly weighed into each test flask.
The test concentrations (10, 32, 100, 320 and 1000 mg/L) were chosen to permit the determination of the EC50. Concentrations in excess of nominal 1000 mg test item/L were not tested.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Origin
The activated sludge was supplied from the sewage plant for domestic sewage in Veszprém, Hungary.

Conditioning
The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was resuspended in isotonic saline solution and again centrifuged. This procedure was repeated twice. An aliquot of the final sludge suspension was weighed, dried and a ratio of wet sludge to its dry weight determined. Based on this ratio, calculated amounts of wet sludge was suspended in isotonic saline solution to yield a concentration equivalent to 4 g per litre (on dry weight basis). During holding prior to use the sludge was fed daily with 50 mL synthetic sewage (see below) per litre and kept aerated at room temperature until use. Before use, the dry weight of the activated sludge was measured again, and the measured value of the dry weight was adequate. The pH of the activated sludge inoculum was determined to be pH 7.88.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

No post exposure period

Test temperature:

19.3 – 20.3 degree C (during the incubation) and 19.1 – 20.5 degree C (during oxygen measurement)

pH:

The pH of the activated sludge inoculum was determined to be pH 7.88.

Dissolved oxygen:

The concentration of dissolved oxygen did not drop below 2.5 mg O2/L during the incubation period, and just before the measurements of the respiration rates the oxygen concentrations were at least 6.5 mg O2/L.

Nominal and measured concentrations:

Test Solutions: Just before the start of the test defined amounts of the test item were directly weighed into each test flask.
The test concentrations (10, 32, 100, 320 and 1000 mg/L) were chosen to permit the determination of the EC50. Concentrations in excess of nominal 1000 mg test item/L were not tested.

Details on test conditions:

Test Solutions:
Just before the start of the test defined amounts of the test item were directly weighed into each test flask.
The test concentrations (10, 32, 100, 320 and 1000 mg/L) were chosen to permit the determination of the EC50. Concentrations in excess of nominal 1000 mg test item/L were not tested.

Control
Two controls (deionised water, synthetic sewage and inoculum, but without addition of the test item) were tested in parallel.

Ratio of test compounds:
One test solution with a final volume of 500 mL is tested per treatment in a glass flask. 16 mL synthetic sewage and an adequate amount of the test item or an adequate volume of the stock solutions of the reference item is filled up with deionised water to 300 mL before the start of the test. At the start of the test 200 mL activated sludge inoculum with a sludge concentration of 4 g/L (dry weight) is added, first to control 1, then in time intervals of approximately 15 minutes (an arbitrary but convenient interval) to the test solutions of the reference item and the test item and finally to an additional control.

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

79.2 mg/L

Conc. based on:

test mat.

Remarks:

LiOH anhydrous

Remarks on result:

other: calculated by linear regression

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

114.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

LiOH anhydrous

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 95% CL: 98.9 - 132.0 mg/L

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

180.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

LiOH anhydrous

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 95% CL: 160.5 - 203.7 mg/L

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

286.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

LiOH anhydrous

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 95%CL: 248.5 - 329.5 mg/L

Details on results:

Inhibition of Respiration Rate:
In comparison to the inoculum controls the respiration rate of the activated sludge was inhibited by –1.8 % at the lowest nominal concentration of 10.0 mg/L.
At the nominal concentrations of 32 and 100 mg/L, the respiration rate was inhibited by 1.8 % and 7.1 %, respectively.
At the nominal concentrations of 320 and 1000 mg test item/L, the respiration rate was inhibited by 94.6 % and 98.2 %, respectively.

Results with reference substance (positive control):

Inhibition of Respiration Rate:
The following nominal concentrations of the positive control 3,5-Dichlorophenol were tested on the same activated sludge and under identical conditions as the test item: 32, 10 and 3.2 mg/L.
In comparison to the controls the respiration rate of the activated sludge was inhibited by 23.2 % at the lowest nominal concentration of 3.2 mg/L.
At the nominal concentrations of 10 and 32 mg/L, the respiration rate was inhibited by 64.3 % and 85.7 %, respectively.
3-hour EC 20, EC 50 and EC 80 of reference item:
The 3-hour EC 50 of 3,5-Dichlorophenol was calculated to be 7.5 mg/L with 95 % confidence limits of 6.1 to 9.2 mg/L.

Reported statistics and error estimates:

Based on measured inhibition rates, the 3-hour EC 20, EC 50 and EC 80 and their 95 %-confidence limits were calculated by Probit analysis using TOXSTAT software.

Table 1: Influence of test item on oxygen consumption of activated sludge

 

Flask No.	Identification	Concentration	Oxygen consumption	Inhibition	pH-values		Oxygen concentration (mg O2/L)
		(mg/L)	(mg O2/L/min)	%	start *	end *	start *	end *
1	Control	-	0.570	-	7.74	7.89	7.5	8.3
10	Control	-	0.550	-	7.70	7.86	7.6	8.7
	mean	-	0.560	-	-	-	-	-
	% deviation	-	3.5	-	-	-	-	-
5	Test item	10	0.570	-1.8	8.38	8.54	7.5	8.4
6	Test item	32	0.550	1.8	8.76	8.97	7.6	8.4
7	Test item	100	0.520	7.1	9.62	9.79	7.7	8.3
8	Test item	320	0.030	94.6	11.53	11.72	7.8	9.3
9	Test item	1000	0.010	98.2	12.30	12.51	7.6	9.4

*   start and end of 3-hour aeration

Table 2: Influence of reference item on oxygen consumption of activated sludge

 

Flask No.	Identification	Concentration	Oxygen consumption	Inhibition	pH-values		Oxygen concentration (mg O2/L)
		(mg/L)	(mg O2/L/min)	%	start *	end *	start *	end *
1	Control	-	0.570	-	7.74	7.89	7.5	8.3
10	Control	-	0.550	-	7.70	7.86	7.6	8.7
	mean	-	0.560	-	-	-	-	-
	% deviation	-	3.5	-	-	-	-	-
2	3,5-DCP	3.2	0.430	23.2	7.79	7.92	7.6	8.3
3	3,5-DCP	10.0	0.200	64.3	7.89	8.07	7.6	8.7
4	3,5-DCP	32.0	0.080	85.7	7.92	8.16	7.6	9.2

*   start and end of 3-hour aeration

3,5-DCP: 3,5-Dichlorophenol

Validity criteria fulfilled:

yes

Conclusions:

The 3 hours EC20, EC50, and EC80 values for the test substance lithium hydroxide in the Activated Sludge Respiration Inhibition Test were 114.3, 180.8, and 286.1 mg/L (based on measured inhibition rates), respectively. The EC10 value was calculated by linear regression to be 79.2 mg/L for lithium hydroxide anhydrous.

Executive summary:

The influence of the test item lithium hydroxide on the activity of activated sludge by measuring the respiration rate was evaluated according to OECD Guideline 209 and EU method C.11. The respiration rate (oxygen consumption) of an aerobic activated sludge fed with a standard amount of synthetic sewage was measured in the presence of various concentrations of the test item after an incubation period of 3 hours. The inhibitory effect of the test item at the particular concentrations was expressed as percentage of the mean respiration rate of two controls. Following test concentrations were used: 10, 32, 100, 320 and 1000 mg lithium hydroxide/L; 3.2, 10 and 32 mg 3,5-Dichlorophenol/L and two inoculum controls. In comparison to the inoculum controls the respiration rate of the activated sludge was inhibited between –1.8% and 98.2 % up to the highest nominal test concentration of 1000 mg/L. Concentrations exceeding 1000 mg/L nominal were not tested. The 3-hour EC 50 for the positive control 3,5-Dichlorophenol, which was tested in the same way as the test item, was found to be 7.5 mg/L and is within the range of 5 – 30 mg/L recommended by the test guidelines; thus, confirming suitability of the activated sludge.

The 3 hours EC20, EC50, and EC80 values for the test substance lithium hydroxide in the Activated Sludge Respiration Inhibition Test were 114.3, 180.8, and 286.1 mg/L (based on measured inhibition rates), respectively. The EC10 value was calculated by linear regression to be 79.2 mg/L for lithium hydroxide anhydrous.

Reference 2

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

no guideline followed

Principles of method if other than guideline:

The EU RAR summarises the results of a number of studies. No details about method and guidelines are given.

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

other: various

Test type:

static

Water media type:

freshwater

Remarks on exposure duration:

The exposure time varies from 3 h to 72 hours.

Reference substance (positive control):

not specified

Key result

Duration:

16 h

Dose descriptor:

NOEC

Effect conc.:

231 mg/L

Nominal / measured:

not specified

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

not specified

Remarks on result:

other: Pseudomonas putida (Bringmann & Kühn 1981)

Duration:

20 h

Dose descriptor:

NOEC

Effect conc.:

7.1 mg/L

Nominal / measured:

not specified

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

not specified

Remarks on result:

other: Uronema parduczi (Bringmann & Kühn 1981)

Duration:

28 h

Dose descriptor:

NOEC

Effect conc.:

226 mg/L

Nominal / measured:

not specified

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

not specified

Remarks on result:

other: Microregma heterotoma (Bringmann & Kühn 1981)

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

83 mg/L

Nominal / measured:

not specified

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

not specified

Remarks on result:

other: Chlomonas paramaecium (Bringmann & Kühn 1981)

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

180 mg/L

Nominal / measured:

not specified

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

not specified

Remarks on result:

other: Eschericia coli (Bringmann & Kühn 1981)

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

101 mg/L

Nominal / measured:

not specified

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

not specified

Remarks on result:

other: Entosiphon sulcatum (Bringmann & Kühn 1981)

The EU RAR reports NOEC values between 7.1 and 231 mg F/L.

Validity criteria fulfilled:

not specified

Conclusions:

The EU RAR reports NOEC values between 7.1 and 231 mg F/L.

Executive summary:

The EU RAR summarizes and reviews the available data on the toxicity of fluoride to aquatic microorganisms. Expressed in terms of fluoride ion (F-), NOEC values between 7.1 and 231 mg F/L were reported.

Description of key information

In an Activated Sludge Respiration Inhibition Test with lithium hydroxide, the 3 hours EC20, EC50, and EC80 values were 114.3, 180.8, and 286.1 mg LiOH/L (based on measured inhibition rates), respectively (LAB 2004). The EC10 value was calculated by linear regression to be 79.2 mg /L for lithium hydroxide. After recalculation of the 3 hours EC10, EC20, EC50 and EC80 values for lithium fluoride the following values were determined: 85.78, 156.07, 195.82 and 390.64 mg LiF/L, respectively.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

85.78 mg/L

Additional information

A microorganism toxicity test with lithium fluoride is not available. Consequently, read-across was applied using study results obtained from lithium hydroxide and sodium fluoride.

 

Read-across with lithium hydroxide (LAB 2004):

The influence of the test item lithium hydroxide on the activity of activated sludge by measuring the respiration rate was evaluated according to OECD guideline 209 and EU method C.11. Aerobic activated sludge fed with a standard amount of synthetic sewage was exposed to 0, 10, 32, 100, 320 and 1000 mg lithium hydroxide/L. In comparison to the inoculum controls the respiration rate of the activated sludge was inhibited between –1.8 % and 98.2 % up to the highest nominal test concentration of 1000 mg/L. The 3 hours EC20, EC50, and EC80 values for the test substance, lithium hydroxide, in the Activated Sludge Respiration Inhibition Test were 114.3, 180.8, and 286.1 mg/L (based on measured inhibition rates), respectively. The EC10 value was calculated by linear regression to be 79.2 mg/L for lithium hydroxide anhydrous.

After recalculation of the 3 hours EC10, EC20, EC50 and EC80 values for lithium fluoride the following values were determined: 85.78, 156.07, 195.82 and 390.64 mg LiF/L, respectively.

 

Read-across with sodium fluoride (EU-RAR 2001):

The EU-RAR summarizes and reviews the available data on the toxicity of fluoride to aquatic microorganisms. Expressed in terms of fluoride ion (F-), NOEC values between 7.1 and 231 mg F/L were reported. Based on these data, the recalculated NOEC values for lithium fluoride were between 9.69 and 315.41 mg/L, respectively. The tests were performed with various species and exposed for various periods of time. Therefore, the results of the EU-RAR review were not chosen as key value for chemical safety assessment.

 

Conclusion:

The results of the Activated Sludge Respiration Inhibition Test (LAB 2004), performed according to OECD 209, seems to be the most reliable data source. Therefore, the EC10 value of 85.78 mg LiF/L is chosen as key value for chemical safety assessment.