Orthosulfamuron

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

Study period:

2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Specific details on test material used for the study:

Test material:
IR5878
Batch number: FCF/T/168-00 (20525/03/9)
Purity: 98.54 ± 0.51 %

Analytical monitoring:

yes

Details on sampling:

Duplicate samples were taken at the start of the test from the freshly prepared test media (without algae) of all test concentrations and from the control. For the determination of the stability of the test item under the test conditions respectively the maintenance of the test item concentrations during the test period, sufficient volumes of the freshly prepared test media of all test concentrations and the control were incubated under the same conditions as in the actual test (but without algae), and were sampled in duplicate at the end of the test (after the 72 hours test period).

Details on test solutions:

Groups of 3 parallel exponentially growing cultures were treated at the concentrations of 4.6, 10, 21, 46 and 100 mg/L and incubated in a water bath. Six replicates were used in the control. The initial biomass was of 10000 algal cells per mL test medium. The volumes were of 50 mL algal suspension per replicate and were continuously stirred by magnetic stirrers in 50 mL Erlenmeyer flasks. Additionally, one replicate per test concentration was prepared without algae to provide as blank for the spectrophotometrical measurements. The additional replicates were incubated under the same conditions as described above. These blank values were subtracted from the absorption measured in the samples containing algae in order to eliminate absorption caused by the test item.

Test organisms (species):

other: Scenedesmus subspicatus

Details on test organisms:

Test system:
Species and Strain: Scenedesmus subspicatus CHODAT, Strain No. 86.81 SAG
Housing: 10000 algal cells per mL test medium per test flasks (at test started).

Water media type:

freshwater

Total exposure duration:

72 h

Test temperature:

Water temperature: 23°C

pH:

pH water: 7.4 ÷ 8.1 (at test start); 8.2 ÷ 10.3 (at test end)

Nominal and measured concentrations:

Groups of 3 parallel exponentially growing cultures were treated at the concentrations of 4.6, 10, 21, 46 and 100 mg/L and incubated in a water bath. During the test period test item concentrations were measured in the range from 82 % to 90 % of the nominal values. Under the test conditions the test item was sufficiently stable during the test period of 72 hours. Therefore, all reported results are related to nominal concentrations of the test item.

Details on test conditions:

Environmental conditions:
Water temperature: 23°C; pH water: 7.4 ÷ 8.1 (at test start), 8.2 ÷ 10.3 (at test end)
Light: continuous illumination at 7980 ÷ 8780 Lux

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 41.4 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

>= 15.1 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 10 ng/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 21 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 87.1 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

>= 24.4 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 10 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 21 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Details on results:

Findings
During the test period test item concentrations were measured in the range from 82 % to 90 % of the nominal values. Under the test conditions the test item was sufficiently stable during the test period of 72 hours. Therefore, all reported results are related to nominal concentrations of the test item.
IR5878 had a statistically significant inhibitory effect on the growth of Scenedesmus subspicatus after the exposure period of 72 hours first at the nominal concentration of 21 mg/L. Thus, this test concentration was determined as the 72-hour LOEC (lowest concentration tested with toxic effects).
The 72-hour NOEC (highest concentration tested without toxic effects after a test period of 72 hours) was determined at the nominal concentration of 10 mg/L, since at this test concentration both the mean biomass and the mean growth rates of the algae were statistically not significantly lower than in the control.

During the test period test item concentrations were measured in the range of 82 -90% of the nominal values. Under the test conditions the test item was sufficiently stable during the test period of 72 hours. Therefore all reported results are related to nomical concentrations of the test item.

Validity criteria fulfilled:

yes

Conclusions:

Conclusions
The EC-values calculated for both parameters, the algal biomass b and the growth rate r after 72 hours test duration are summarised in the Table 8.4-1.

Table 8.4-1 Summary of the influence of IR5878 on the growth of Scenedesmus subspicatus
Parameter (0-72 hours) Biomass b (mg/L) Growth rate r (mg/L)
EC50 41.4 87.1
95% conf. limits 34.8 – 49.9 74.6 – 105.7
EC10 15.1 24.4
95% conf. limits 10.6 – 19.1 19.8 – 28.7
NOEC (72-h) 10 10
LOEC (72-h) 21 21

Executive summary:

A study was performed to evaluate the inhibitory effect of IR5878 on the growth of the freshwater green algal speciesScenedesmus subspicatus. Groups of 3 parallel exponentially growing cultures were treated at the concentrations of 4.6, 10, 21, 46 and 100 mg/L and incubated in a water bath.EC₅₀(biomass) was 41.4 mg/L. EC₅₀(growth rate) was 87.1 mg/L. NOEC (72-h) for biomass and growth rate was 10 mg/L. LOEC (72-h) for biomass and growth rate was 21 mg/L

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Specific details on test material used for the study:

Test material:
IR5878
Batch number: G 009/02
Purity: 98.56 ± 0.19 %

Analytical monitoring:

yes

Details on sampling:

Groups of 3 parallel exponentially growing cultures were treated at the concentrations of 0.21, 0.46, 1.0, 2.1, 4.6, 10 and 21 mg/L and incubated in a water bath. Six replicates were used in the control. The initial biomass was of 10000 algal cells per mL test medium. The volumes were of 50 mL algal suspension per replicate and were continuously stirred by magnetic stirrers in 50 mL Erlenmeyer flasks. Additionally, one replicate per test concentration was prepared without algae to provide as blank for the spectrophotometrical measurements. The additional replicates were incubated under the same conditions as described above. These blank values were subtracted from the absorption measured in the samples containing algae in order to eliminate absorption caused by test item only after 72 hours test duration. After 24 and 48 hours test duration the absorption of the blanks were not subtracted, since they were nearly 0.
The inhibition of growth in relation to control cultures was determined over a test period of 72 hours, and thus over several algal generations.
Duplicate samples were taken at the start of the test from the freshly prepared test media (without algae) of all test concentrations and from the control. For the determination of the stability of the test item under the test conditions respectively the maintenance of the test item concentrations during the test period, sufficient volumes of the freshly prepared test media of all test concentrations and the control were incubated under the same conditions as in the actual test (but without algae), and were sampled in duplicate at the end of the test (after the 72 hours test period).

Details on test solutions:

Groups of 3 parallel exponentially growing cultures were treated at the concentrations of 0.21, 0.46, 1.0, 2.1, 4.6, 10 and 21 mg/L and incubated in a water bath

Test organisms (species):

Anabaena flos-aquae

Details on test organisms:

Test system:
Species and Strain: Anabaena flos-aquae
Housing: 10000 algal cells per mL test medium per test flasks (when test started).
The algae was supplied by UTEX The Culture Collection of Algae, Molecular Cell Developmental Biology, BioLabs 311, The University of Texas at Austin, Austin, TX 78712

Water media type:

freshwater

Total exposure duration:

72 h

Test temperature:

Water temperature: 23°C

pH:

pH water: 6.3 ÷ 6.7 (at test start), 5.4 ÷ 6.4 (at test end)

Nominal and measured concentrations:

Groups of 3 parallel exponentially growing cultures were treated at the concentrations of 0.21, 0.46, 1.0, 2.1, 4.6, 10 and 21 mg/L and incubated in a water bath. In the stock solution 88% of nominal concentration was found. Since the test item was not stable during the test period of 72 hours under test conditions, the reported results are related to mean measured test concentrations. The recovery of the lowest concentration (0.21 mg/L) was determined mathematically.

Details on test conditions:

Environmental conditions:
Water temperature: 23°C; pH water: 6.3 ÷ 6.7 (at test start), 5.4 ÷ 6.4 (at test end)
Light: continuous illumination at 7420 ÷ 7820 Lux

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 1.9 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

act. ingr.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

>= 0.3 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

act. ingr.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.17 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

act. ingr.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 0.36 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

act. ingr.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 13 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

>= 1.2 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.36 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 0.79 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Details on results:

In the stock solution 88% of nominal concentration was found. Since the test item was not stable during the test period of 72 hours under test conditions, the reported results are related to mean measured test concentrations. The recovery of the lowest concentration (0.21 mg/L) was determined mathematically.

Table 8.4-2 Nominal and measured test concentrations
Nominal concentrations (mg/L) Measured concentration (mg/L) %
0.21 0.17 79
0.46 0.36 78
1.00 0.79 79
2.10 1.81 86
4.60 3.63 79
10 7.70 77
21 15.33 73

IR5878 had a statistically significant inhibitory effect on the biomass of Anabaena flos-aquae after the exposure period of 72 hours first at the nominal concentration of 0.36 mg/L (nominal 0.46 mg/L). Thus, this test concentration was determined as the 72-hour LOEC (lowest concentration tested with toxic effects).
The 72-hour NOEC (highest concentration tested without toxic effects after a test period of 72 hours) was determined at the concentration of 0.17 mg/L (nominal 0.21 mg/L), since at this test concentration the mean biomass of the algae was statistically not significantly lower than in the control. The 72-hour NOEC of the growth rate was determined to be 0.36 mg/L (nominal 0.46 mg/L).

Reported statistics and error estimates:

Based on the calculated cell densities the EbC50 and the ErC50 (the concentrations of the test item corresponding to 50% inhibition of algal biomass respectively growth rate comared to the control.) and the corresponding EC 10 and their 95% confidence limits were calculated by Probit analysis. For the calculation of the EC values mean measured test concentrations were taken. For the determination of the LOEC and NOEC the calculated mean biomass and growth rates r at the test concentration were tested on significant differences to the control values by Dunnett-tests.

Findings

In the stock solution 88% of nominal concentration was found. Since the test item was not stable during the test period of 72 hours under test conditions, the reported results are related to mean measured test concentrations. The recovery of the lowest concentration (0.21 mg/L) was determined mathematically.

 

Table 8.4-2     Nominal and measured test concentrations

Nominal concentrations (mg/L)	Measured concentration (mg/L)	%
0.21	0.17	79
0.46	0.36	78
1.00	0.79	79
2.10	1.81	86
4.60	3.63	79
10	7.70	77
21	15.33	73

 

IR5878 had a statistically significant inhibitory effect on the biomass ofAnabaenaflos-aquaeafter the exposure period of 72 hours first at the nominal concentration ofmg/L (nominalmg/L). Thus, this test concentration was determined as the 72-hour LOEC (lowest concentration tested with toxic effects).

The 72-hour NOEC (highest concentration tested without toxic effects after a test period of 72 hours) was determined at the concentration ofmg/L (nominalmg/L), since at this test concentration the mean biomass of the algae was statistically not significantly lower than in the control. The 72-hour NOEC of the growth rate was determined to bemg/L (nominalmg/L).

 

Conclusions

The EC-values calculated for both parameters, the algal biomass b and the growth rate r after 72 hours test duration are summarised in the Table 8.4-3.

 

Table 8.4-3     Summary of the influence of IR5878 on the growth ofAnabaenaflos-aquae

Parameter (0-72 hours)	Biomass b (mg/L)	Growth rate r (mg/L)
EC50	1.9	13.0
95% conf. limits	1.7 – 2.3	12.1 – 14.1
EC10	0.3	1.2
95% conf. limits	0.2 – 0.4	1.0 – 1.3
NOEC (72-h)	0.17	0.36
LOEC (72-h)	0.36	0.79

 

 

Validity criteria fulfilled:

yes

Conclusions:

Conclusions
The EC-values calculated for both parameters, the algal biomass b and the growth rate r after 72 hours test duration are summarised in the Table 8.4-3.

Table 8.4-3 Summary of the influence of IR5878 on the growth of Anabaena flos-aquae
Parameter (0-72 hours) Biomass b (mg/L) Growth rate r (mg/L)
EC50 1.9 13.0
95% conf. limits 1.7 – 2.3 12.1 – 14.1
EC10 0.3 1.2
95% conf. limits 0.2 – 0.4 1.0 – 1.3
NOEC (72-h) 0.17 0.36
LOEC (72-h) 0.36 0.79

Executive summary:

Executive summary

A study was performed to evaluate the inhibitory effect of IR5878 on the growth of the freshwater blue algal species Anabaena flos-aquae. Groups of 3 parallel exponentially growing cultures were treated at the concentrations of 0.46, 1.0, 2.1, 4.6, 10 and 21 mg/L and incubated in a water bath.

EC₅₀(biomass) was 1.9 mg/L. EC₅₀(growth rate) was 13.0 mg/L. NOEC (72-h) for biomass was 0.17mg/L. NOEC (72-h) for growth rate was 0.36mg/L. LOEC (72-h) for biomass was 0.36mg/L. LOEC (72-h) for growth rate was 0.79 mg/L.

Description of key information

A study was performed to evaluate the inhibitory effect of IR5878 on the growth of the freshwater green algal species Scenedesmus subspicatus. Groups of 3 parallel exponentially growing cultures were treated at the concentrations of 4.6, 10, 21, 46 and 100 mg/L and incubated in a water bath. EC₅₀(biomass) was 41.4 mg/L. EC₅₀ (growth rate) was 87.1 mg/L. NOEC (72-h) for biomass and growth rate was 10 mg/L. LOEC (72-h) for biomass and growth rate was 21 mg/L.

A study was performed to evaluate the inhibitory effect of IR5878 on the growth of the freshwater blue algal speciesAnabaena flos-aquae. Groups of 3 parallel exponentially growing cultures were treated at the concentrations of 0.46, 1.0, 2.1, 4.6, 10 and 21 mg/L and incubated in a water bath.

EC₅₀(biomass) was 1.9 mg/L. EC₅₀(growth rate) was 13.0 mg/L. NOEC (72-h) for biomass was 0.17mg/L. NOEC (72-h) for growth rate was 0.36mg/L. LOEC (72-h) for biomass was 0.36mg/L. LOEC (72-h) for growth rate was 0.79 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

1.9 mg/L