Sulfaguanidine

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:

comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EPA OTS 797.1050 (Algal Toxicity, Tiers I and II)

Version / remarks:

2005

GLP compliance:

not specified

Specific details on test material used for the study:

Sulfaguanidine was purchased from Sigma–Aldrich with minimum purity of 99%.

Analytical monitoring:

yes

Details on sampling:

To check for the stability of the compounds, samples of freshly prepared and 96-h-old test solutions (with/without test organisms) were collected. As the media did not interfere with the analysis, extraction and purification were unnecessary. Samples were simply filtered through Phenex- PTFE 0.45 lm (Phenomenex, Castelmaggiore, Italy) and then analyzed by means of HPLC, with UV detector set at 268 nm.

Vehicle:

no

Details on test solutions:

For the preparation of the BBM medium (bold basal medium) all the ingredients used were of analytical quality and purchased from Sigma–Aldrich (Milano, Italy). Fresh stock solutions were prepared just before each experiment by diluting in the proper medium (BBM) the compound to be tested. Where necessary, the solubilization was achieved by bringing back the pH of the medium to the original value using 1 M NaOH. The pH was measured using a BASIC 20 pH meter (CRISON, Carpi, Italy). All working solutions used in tests were prepared by appropriately diluting the stock solution with medium to the requested concentration.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

The algae used for the tests was from axenic cultures of P. subcapitata (strain UTEX 1648) in mid exponential phase. The culture was maintained at 24 ± 1 °C in bold basal medium (BBM; Nichols, 1973) with continuously bubbling air, and kept under continuous illumination (90 ± 10% µE/s/m²).

Test type:

static

Water media type:

other: BBM media

Total exposure duration:

96 h

Test temperature:

24 ± 1 °C

pH:

No significant pH variations were recorded during the 96-h incubation period.

Nominal and measured concentrations:

As the concentrations of the tested substance were maintained within ±20% of the initial concentration, test results were based on nominal values. The range of nominal values was 5-80 mg/L.

Details on test conditions:

Algal inocula corresponding to 10 000 cells/mL were grown in 125 mL Erlenmeyer flasks containing 50 mL of either BBM alone (controls) or BBM and sulfaguanidine. Based on preliminary results, five (or more) different concentrations in a geometric series with a factor of 2 were tested. The tests were carried out in triplicate and in axenic conditions. The flasks were incubated on a shaking ( ̴100 RPM) apparatus at the same conditions (continuous illumination 90 ± 10% µE/s/m² and 24 ± 1 °C temperature). After 96 h the algal growth was measured by counting the cells in a Burker chamber. At end the of each test, algistatic effect was differentiated from algicidal effect by subculturing in BBM a 0.5 mL aliquot of test solution containing growth-inhibited algae.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

20 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

LOEC

Effect conc.:

40 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC20

Effect conc.:

27.415 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

43.559 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

CONFIDENCE INTERVALS (95% confidence level):
EC20: 25.446 - 29.380 mg/L
EC50: 38.255 - 49.373 mg/L

Results with reference substance (positive control):

None

Validity criteria fulfilled:

not specified

Conclusions:

Sulfaguanidine toxicity on the algae P. subcapitata was determined in a 96h study in axenic conditions, resulting in a 96-hour LOEC of 40 mg/L and NOEC of 20 mg/L.
EC20 was calculated to be 27.415 mg/L while EC50 was calculated to be 43.559 mg/L.

Executive summary:

The toxicity of sulfaguanidine (SGD) to the freshwater green algae P. subcapitata was evaluated in a 96h test in acenic conditions (797.1050-algal acute toxicity test CFR US-EPA, 2005).

Based on results from statistical analysis, sulfaguanidine toxicity on the algae P. subcapitata resulted in a 96 -hour LOEC of 40mg/L and NOEC of 20mg/L.

EC20 was calculated to be 27.415 mg/L while EC50 was calculated to be 43.559 mg/L.

Reference 2

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:

comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EPA OTS 797.1050 (Algal Toxicity, Tiers I and II)

Version / remarks:

2005

GLP compliance:

not specified

Specific details on test material used for the study:

Sulfaguanidine was purchased from Sigma–Aldrich with minimum purity of 99%.

Analytical monitoring:

yes

Details on sampling:

To check for the stability of the compounds, samples of freshly prepared 96-h-old test solutions (with/without test organisms) were collected. As the media did not interfere with the analysis, extraction and purification were unnecessary. Samples were simply filtered through Phenex- PTFE 0.45 µm (Phenomenex, Castelmaggiore, Italy) and then analyzed by means of HPLC, with UV detector set at 268 nm.

Vehicle:

no

Details on test solutions:

For the preparation of the BBM medium (bold basal medium) all the ingredients used were of analytical quality and purchased from Sigma–Aldrich (Milano, Italy). Fresh stock solutions were prepared just before each experiment by diluting in the proper medium (BBM) the compound to be tested. Where necessary, the solubilization was achieved by bringing back the pH of the medium to the original value using 1 M NaOH. The pH was measured using a BASIC 20 pH meter (CRISON, Carpi, Italy). All working solutions used in tests were prepared by appropriately diluting the stock solution with medium to the requested concentration.

Test organisms (species):

other: Scenedesmus dimorphus

Details on test organisms:

The algae used for the tests were from axenic culture of S. dimorphus (strain ACUF 231) in mid exponential phase. The culture was maintained at 24 ± 1 °C in bold basal medium (BBM; Nichols, 1973, Growth media-freshwater. In: Stein, J.R. (Ed.), Handbook of Phycological Methods. Cambridge University Press, Cambridge, pp. 7–24.) with continuously bubbling air, and kept under continuous illumination (90 ± 10% µE/s/m²).

Test type:

static

Water media type:

other: BBM media

Total exposure duration:

96 h

Test temperature:

24 ± 1 °C

pH:

No significant pH variations were recorded during the 96-h incubation period.

Nominal and measured concentrations:

As the concentrations of the tested substance were maintained within ±20% of the initial concentration, test results were based on nominal values. The range of nominal values was 0.61-10mg/L.

Details on test conditions:

Algal inocula corresponding to 10 000 cells/mL were grown in 125 mL Erlenmeyer flasks containing 50 mL of either BBM alone (controls) or BBM and sulfaguanidine. Based on preliminary results, five (or more) different concentrations in a geometric series with a factor of 2 were tested. The tests were carried out in triplicate and in axenic conditions. The flasks were incubated on a shaking ( ̴100 RPM) apparatus at the same conditions (continuous illumination 90 ± 10% µE/s/m² and 24 ± 1 °C temperature). After 96 h the algal growth was measured by counting the cells in a Burker chamber. At end the of each test, algistatic effect was differentiated from algicidal effect by subculturing in BBM a 0.5 mL aliquot of test solution containing growth-inhibited algae.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

1.25 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

LOEC

Effect conc.:

2.5 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC20

Effect conc.:

1.656 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

3.4 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

CONFIDENCE INTERVALS (95% confidence level):
EC20: 0.780 - 1.969 mg/L
EC50: 3.134 - 3.673 mg/L

Results with reference substance (positive control):

None

Validity criteria fulfilled:

not specified

Conclusions:

Sulfaguanidine toxicity on the algae S.dimorphus was determined in a 96h study in axenic conditions, resulting in a 96-hour LOEC of 2.5 mg/L and NOEC of 1.25 mg/L.
EC20 was calculated to be 1.656 mg/L while EC50 was calculated to be 3.4 mg/L.

Executive summary:

The toxicity of sulfaguanidine (SGD) to the freshwater green algae S. dimorphus was evaluated in a 96h test in axenic conditions (797.1050-algal acute toxicity test CFR US-EPA, 2005).

Based on results from statistical analysis, sulfaguanidine toxicity on the algae S. dimorphus resulted in a 96 -hour LOEC of 2.5 mg/L and NOEC of 1.25 mg/L.

EC20 was calculated to be 1.656 mg/L while EC50 was calculated to be 3.4 mg/L.

Reference 3

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:

comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EPA OTS 797.1050 (Algal Toxicity, Tiers I and II)

Version / remarks:

2005

GLP compliance:

not specified

Specific details on test material used for the study:

Sulfaguanidine was purchased from Sigma–Aldrich with minimum purity of 99%.

Analytical monitoring:

yes

Details on sampling:

To check for the stability of the compounds, samples of freshly prepared and 96-h-old test solutions (with/without test organisms) were collected. As the media did not interfere with the analysis, extraction and purification were unnecessary. Samples were simply filtered through Phenex- PTFE 0.45 lm (Phenomenex, Castelmaggiore, Italy) and then analyzed by means of HPLC, with UV detector set at 268 nm.

Vehicle:

no

Details on test solutions:

For the preparation of the BBM medium (bold basal medium) all the ingredients used were of analytical quality and purchased from Sigma–Aldrich (Milano, Italy). Fresh stock solutions were prepared just before each experiment by diluting in the proper medium (BBM) the compound to be tested. Where necessary, the solubilization was achieved by bringing back the pH of the medium to the original value using 1 M NaOH. The pH was measured using a BASIC 20 pH meter (CRISON, Carpi, Italy). All working solutions used in tests were prepared by appropriately diluting the stock solution with medium to the requested concentration.

Test organisms (species):

other: Synecoccus leopoliensis

Details on test organisms:

The cyanobacteria used for the test was from axenic culture of S. leopoliensis (strain UTEX 625) in mid exponential phase. The culture was maintained at 24 ± 1 °C in bold basal medium (BBM; Nichols, 1973) with continuously bubbling air, and kept under continuous illumination (90 ± 10% µE/s/m²).

Test type:

static

Water media type:

other: BBM media

Total exposure duration:

96 h

Test temperature:

24 ± 1 °C

pH:

No significant pH variations were recorded during the 96-h incubation period.

Nominal and measured concentrations:

As the concentrations of the tested substance were maintained within ±20% of the initial concentration, test results were based on nominal values. The range of nominal values was 2.5-40 mg/L.

Details on test conditions:

Algal inocula corresponding to 10 000 cells/mL were grown in 125 mL Erlenmeyer flasks containing 50 mL of either BBM alone (controls) or BBM and the assayed compound. Based on preliminary results, five (or more) different concentrations in a geometric series with a factor of 2 were tested. The tests were carried out in triplicate and in axenic conditions. The flasks were incubated on a shaking ( ̴100 RPM) apparatus at the same conditions (continuous illumination 90 ± 10% µE/s/m² and 24 ± 1 °C temperature). After 96 h the algal growth was measured by using in vivo fluorimetric detection of chlorophyll with a Turner Aquafluor TM fluorimeter. At end the of each test, algistatic effect was differentiated from algicidal effect by subculturing in BBM a 0.5 mL aliquot of test solution containing growth-inhibited cyanobacteria.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

5 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

LOEC

Effect conc.:

10 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC20

Effect conc.:

8.789 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

16.594 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

CONFIDENCE INTERVALS (95% confidence level):
EC20: 7.847 - 10.464 mg/L
EC50: 15.440 - 17.552 mg/L

Results with reference substance (positive control):

None

Validity criteria fulfilled:

not specified

Conclusions:

Sulfaguanidine toxicity on the cyanobacteria S. leopoliensis was determined in a 96h study in axenic conditions, resulting in a 96-hour LOEC of 10 mg/L and NOEC of 5 mg/L.
EC20 was calculated to be 8.789 mg/L while EC50 was calculated to be 16.594 mg/L.

Executive summary:

The toxicity of sulfaguanidine (SGD) to the freshwater cyanobacteria S. leopoliensis was evaluated in a 96h test in axenic conditions (797.1050-algal acute toxicity test CFR US-EPA, 2005).

Based on results from statistical analysis, sulfaguanidine towicity on the cyanobacteria S. leopoliensis resulted in a 96-hour LOEC of 10 mg/L and NOEC of 5 mg/L.

EC20 was calculated to be 8.789 mg/L while EC50 was calculated to be 16.594 mg/L.

Description of key information

The toxicity of sulfaguanidine (SGD) to the freshwater green algae P. subcapitata and S. dimorphus and to the cyanobacterium S. leopoliensis, was evaluated using the 797.1050-algal acute toxicity test (CFR US-EPA, 2005).

From this growth inhibition toxicity test, the 96-h NOEC of SGD to algae P. subcapitata and S. dimorphus and to the cyanobacterium S. leopoliensis were determined to be 20, 1.25 and 5mg/L, respectively.

The EC50 values were 3.400 mg/L for S. dimorphus, 43.559 mg/L for P. subcapitata and 16.594 mg/L for S. leopoliensis.

Key value for chemical safety assessment

EC50 for freshwater algae:

3.4 mg/L

EC10 or NOEC for freshwater algae:

1.25 mg/L