Potassium tetrahydroborate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Materials and methods are described in detail. Peer-reviewed publication that meets basic scientific principles.

Qualifier:

no guideline available

Principles of method if other than guideline:

Materials and methods are described in detail. Peer-reviewed publication that meets basic scientific principles.

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

other: Several organisms cultures of 19 species were chosen at random from 10 classes of algae. See results and discussion for more information.

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

10 d

Test temperature:

16 - 20 °C

pH:

7.6 - 8.0

Salinity:

3 %

Nominal and measured concentrations:

Nominal concentrations : 0, 5, 10, 50, 100 mg/L boric acid

Reference substance (positive control):

not specified

Key result

Duration:

10 d

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: NOEC for 18 out of 19 species, the growth rate monallantus salina was already reduced at this concentration

Key result

Duration:

10 d

Dose descriptor:

LOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: LOEC for Monallantus salina

Key result

Duration:

10 d

Dose descriptor:

EC50

Effect conc.:

> 50 - < 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: The EC50 was determined to be between 50 and 100 mg/L based on the average growth rates over all tested species.

Table 1: Summary of boron concentration effects on phytoplankter growth.

		% growth rate*	% growth rate*	% growth rate*	% growth rate*
class	species	0 - 5 mg/L boric acid	10 mg/L boric acid	50 mg/L boric acid	100 mg/L boric acid
Chlorophyceae	Dunaliella tertiolecta	100	100	100	82
Prasinophyceae	Tetraselmis maculata	100	100	42	43
Haptophyceae	Emiliania huxleyi	100	-	32	0
Haptophyceae	Isochrysis galbana	100	100	0	0
Chrysophyceae	Monochrysis lutheri	100	105	62	33
Eustigmatophyceae	Nannochloris oculata	100	96	85	86
Eustigmatophyceae	Monallantus salina	100	88	77	65
Bacillariophyceae (diatoms)	Phaodactylum tricornutum	100	96	46	46
Bacillariophyceae (diatoms)	Thalassiosira fluviatilis	100	100	100	0
Bacillariophyceae (diatoms)	Thalassiosira pseudonana	100	100	100	100
Bacillariophyceae (diatoms)	Cyclotella cryptica	100	100	86	0
Bacillariophyceae (diatoms)	Skeletonema costatum	100	129	79	0
Bacillariophyceae (diatoms)	Bellerochea polymorpha	100	100	92	46
Cryptophyceae	Chroomonas salina	100	100	71	0
Cryptophyceae	Rhodomonas lens	100	125	31	0
Dinophyceae	Amphidinium carteri	100	100	72	0
Rhodophyceae	Porphyridium cruentum	100	100	105	82
Cyanophyceae	Agmenellum quadruplicatum	100	100	100	100
Cyanophyceae	Anacystis marina	100	123	118	95

*Maximum (exponential) growth rate expressed as percent of that obtained in control with no added boron.

The growth rate was determined by measuring the optical density.

Validity criteria fulfilled:

yes

Conclusions:

It can be stated that the NOEC is 10 mg/L boric acid for almost all species. Monallantus salina was the only species showing a significant (< 95% growth rate) at this concentration. For this species 10 mg/L boric acid is the LOEC.
The EC50 was determined to be between 50 and 100 mg/L based on the average growth rates over all tested species.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Under standard ecological conditions, potassium tetrahydroborate decomposes to boric acid and borate salts, respectively. Thus the aquatic toxicity of boric acid should be determined to evaluate the toxicity of potassium tetrahydroborate.

Reason / purpose for cross-reference:

read-across source

Qualifier:

no guideline available

Principles of method if other than guideline:

Materials and methods are described in detail. Peer-reviewed publication that meets basic scientific principles.

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

other: Several organisms cultures of 19 species were chosen at random from 10 classes of algae. See results and discussion for more information.

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

10 d

Test temperature:

16 - 20 °C

pH:

7.6 - 8.0

Salinity:

3 %

Nominal and measured concentrations:

Nominal concentrations : 0, 5, 10, 50, 100 mg/L boric acid

Reference substance (positive control):

not specified

Key result

Duration:

10 d

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: NOEC for 18 out of 19 species, the growth rate monallantus salina was already reduced at this concentration

Key result

Duration:

10 d

Dose descriptor:

LOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: LOEC for Monallantus salina

Key result

Duration:

10 d

Dose descriptor:

EC50

Effect conc.:

> 50 - < 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: The EC50 was determined to be between 50 and 100 mg/L based on the average growth rates over all tested species.

Table 1: Summary of boron concentration effects on phytoplankter growth.

		% growth rate*	% growth rate*	% growth rate*	% growth rate*
class	species	0 - 5 mg/L boric acid	10 mg/L boric acid	50 mg/L boric acid	100 mg/L boric acid
Chlorophyceae	Dunaliella tertiolecta	100	100	100	82
Prasinophyceae	Tetraselmis maculata	100	100	42	43
Haptophyceae	Emiliania huxleyi	100	-	32	0
Haptophyceae	Isochrysis galbana	100	100	0	0
Chrysophyceae	Monochrysis lutheri	100	105	62	33
Eustigmatophyceae	Nannochloris oculata	100	96	85	86
Eustigmatophyceae	Monallantus salina	100	88	77	65
Bacillariophyceae (diatoms)	Phaodactylum tricornutum	100	96	46	46
Bacillariophyceae (diatoms)	Thalassiosira fluviatilis	100	100	100	0
Bacillariophyceae (diatoms)	Thalassiosira pseudonana	100	100	100	100
Bacillariophyceae (diatoms)	Cyclotella cryptica	100	100	86	0
Bacillariophyceae (diatoms)	Skeletonema costatum	100	129	79	0
Bacillariophyceae (diatoms)	Bellerochea polymorpha	100	100	92	46
Cryptophyceae	Chroomonas salina	100	100	71	0
Cryptophyceae	Rhodomonas lens	100	125	31	0
Dinophyceae	Amphidinium carteri	100	100	72	0
Rhodophyceae	Porphyridium cruentum	100	100	105	82
Cyanophyceae	Agmenellum quadruplicatum	100	100	100	100
Cyanophyceae	Anacystis marina	100	123	118	95

*Maximum (exponential) growth rate expressed as percent of that obtained in control with no added boron.

The growth rate was determined by measuring the optical density.

Validity criteria fulfilled:

yes

Conclusions:

It can be stated that the NOEC is 10 mg/L boric acid for almost all species. Monallantus salina was the only species showing a significant (< 95% growth rate) at this concentration. For this species 10 mg/L boric acid is the LOEC.
The EC50 was determined to be between 50 and 100 mg/L based on the average growth rates over all tested species.
As boric acid is the decompositon product of potassium tetrahydroborate, the same values can be stated for potassium tetrahydroborate.

Description of key information

19 different algea species were choosen for the test.

It can be stated that the NOEC is 10 mg/L boric acid for almost all species. Monallantus salina was the only species showing a significant (< 95% growth rate) at this concentration. For this species 10 mg/L boric acid is the LOEC.

The EC50 was determined to be between 50 and 100 mg/L based on the average growth rates over all tested species.

As boric acid is the decompositon product of potassium tetrahydroborate, the same values can be stated for potassium tetrahydroborate.

Key value for chemical safety assessment

EC50 for marine water algae:

50 mg/L

EC10 or NOEC for marine water algae:

10 mg/L