N-(2-ethylhexyl)-8,9,10-trinorborn-5-ene-2,3-dicarboximide

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 April 2002 to 17 April 2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

7 June 1984

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

29 December 1992

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

MGK 264
Lot number: 7437
Purity: 94.5%

Analytical monitoring:

yes

Details on sampling:

At the start of the test, the measured levels of MGK 264 in samples of the test cultures ranged between 79 and 98% of their nominal values. After 72 hours, the measured levels ranged between 73 and 99% of nominal; between 91 and 102% of their initial values except at 1.03 mg/L where the measured level was 76% of initial. The overall mean measured levels of MGK 264 were 0.161, 0.370, 0.891, 2.23 and 4.38 mg/L.

Vehicle:

yes

Details on test solutions:

Acetone:
In the third test, where the test media were prepared from a series of acetone stock solutions and stirred overnight, algal cultures were exposed to the test substance at 0.5 to 10 m/l; after 72 hours, growth had been inhibited at 5 mg/I and higher concentrations and the results of chemical analysis at 0 hours indicated that the intended exposure concentrations were achieved.

Test organisms (species):

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

Details on test organisms:

Selenastrum capricomutum, Strain No. CCAP 278/4.

Axenic, uni-cellular, liquid slope cultures of algae were obtained from the Culture Collection of Algae and Protozoa, Institute of Freshwater Ecology, Cumbria, UK and arrived on 21 June 2002.

The liquid slope cultures were stored in an illuminated refrigerator. Sterile algal nutrient medium (Appendix 1) was inoculated with cells aseptically removed from the slope culture; these primary liquid cultures (50 ml) were incubated for approximately three days in an orbital incubator under continuous illumination at nominal temperatures in the range 21 to 25°C. Subsequently, appropriate volumes of these primary cultures were aseptically transferred to fresh sterile algal nutrient medium prepare secondary liquid cultures; these cultures were incubated, as stated above, for a further three days to provide an inoculum in the log phase of growth, characterised by a cell density of 1. 72 x 106 cells/ml. An aliquot of one of the secondary culture was used in the definitive test to give an initial cell density of 1 x 104 cells/ml in the control and test vessels.

Test type:

other: Gaseous exchange and suspension of the algal cells were ensured by the action of the orbital shaker, oscillating at a nominal 150 cycles per minute.

Water media type:

other: ALGAL NUTRIENT MEDIUM (OECD)

Remarks:

See Appendix 1 of attached report for details of salts utilised to make the solution.

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

N/A

Hardness:

Not Measured

Test temperature:

21 to 25°C

pH:

7.44-7.71 (0 Hour)
7.87-9.42 (72 Hour)

Dissolved oxygen:

Not Measured

Salinity:

Not Measured

Conductivity:

Not Measured

Nominal and measured concentrations:

Nominal - 0.213, measured as 0.168 and 0.154 at 0 and 72 hours respectively. Arithmetic mean concentration of 0.161 mg/L
Nominal - 0.213A, measured as 0.144 at 72 hours.
Nominal - 0.470, measured as 0.387 and 0.353 at 0 and 72 hours respectively. Arithmetic mean concentration of 0.370 mg/L
Nominal - 1.03, measured as 1.01 and 0.771 at 0 and 72 hours respectively. Arithmetic mean concentration of 0.891 mg/L
Nominal - 2.27, measured as 2.21 and 2.25 at 0 and 72 hours respectively. Arithmetic mean concentration of 2.23 mg/L
Nominal - 5, measured as 4.35 and 4.40 at 0 and 72 hours respectively. Arithmetic mean concentration of 4.38 mg/L
Nominal - 5A, measured as 4.41 at 72 hours.

Details on test conditions:

Conical flasks (250 mL) each containing 100 mL of control or test culture were placed in an illuminated orbital incubator according to a random number sequence. The cultures were incubated, without renewal of medium for 72 hours under continuous illumination of approximately 8360 lux (mean value) provided by 5 x 30 W "cool white" I metre fluorescent tubes. The temperature was maintained at nominal 23 ± 2°C. Temperature and pH of control and test flasks at the start and end of the test were recorded. Gaseous exchange and suspension of the algal cells were ensured by the action of the orbital shaker, oscillating at a nominal 150 cycles per minute. The minimum, maximum and ambient temperature and light intensity in the test area were determined each day.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

EbC50

Effect conc.:

> 1.63 - < 2.7 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: Area under the growth curve

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

ErC50

Effect conc.:

> 4.38 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

Average specific growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.891 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.891 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: Are under growth curve

Details on results:

The effect of MGK 264 on the growth of the unicellular green alga Selenastrum capricornutum was assessed under non-axenic conditions.

The measured levels of MGK 264 in samples of the test cultures ranged between 79 and 98% of their nominal values at the start of the test and between 73 and 99% of nominal after 72 hours, with overall mean measured levels of 0.161, 0.370, 0.891, 2.23 and 4.38 mg/L.

Cell numbers were counted daily to monitor growth. The test results are expressed in terms of the area under the growth curve and growth rate. The following values were derived from the data:

Area under the growth curve
EbC50 (72 h) 2.28 mg/L (95% confidence limits 1.63 & 2.70 mg/L)
No observed effect concentration (NOEC)

Average specific growth rate
ErC50 (72 h) >4.38 mg/L (32% inhibition)
No observed effect concentration (NOEC)

Results with reference substance (positive control):

N/A

Reported statistics and error estimates:

Area under the growth curve
EbC50 (72 h) 2.28 mg/L (95% confidence limits 1.63 & 2.70mg/L)
No observed effect concentration (NOEC)
Average specific growth rate
ErC50 (72 h) >4.38 mg/L (32% inhibition)
No observed effect concentration (NOEC)

Validity criteria fulfilled:

yes

Conclusions:

After 72 hours of exposure to MGK 264, the EbC50 and ErC50, respectively were 2.28 and> 4.38 mg/L.

The "no observed effect concentration" (NOEC) for both area under the growth curve and growth rate was 0. 891 mg/L.

Executive summary:

The effect of MGK 264 on the growth of the unicellular green alga Selenastrum capricornutum was assessed under non-axenic conditions.

The measured levels of MGK 264 in samples of the test cultures ranged between 79 and 98% of their nominal values at the start of the test and between 73 and 99% of nominal after 72 hours, with overall mean measured levels of 0.161, 0.370, 0.891, 2.23 and 4.38 mg/L.

Cell numbers were counted daily to monitor growth. The test results are expressed in terms of the area under the growth curve and growth rate. The following values were derived from the data:

Area under the growth curve

EbC50 (72 h) 2.28 mg/L (95% confidence limits 1.63 & 2.70mg/L)

No observed effect concentration (NOEC)

Average specific growth rate

ErC50 (72 h) >4.38 mg/L (32% inhibition)

No observed effect concentration (NOEC)

Description of key information

After 72 hours of exposure to MGK 264, the EbC50 and ErC50, respectively were 2.28 and > 4.38 mg/L.

The "no observed effect concentration" (NOEC) for both area under the growth curve and growth rate was 0. 891 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

2.28 mg/L

EC10 or NOEC for freshwater algae:

0.891 mg/L