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

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

5 March 2002 to 16 May 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Qualifier:

according to guideline

Guideline:

other: EC Directive 88/302, 'Biodegradation - Activated Sludge Respiration Inhibition test'

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

MGK 264
Lot number: 7437
Expiry date: 22 January 2003
Purity: 94.5%

Analytical monitoring:

no

Vehicle:

no

Remarks:

dechlorinated tap water was used

Details on test solutions:

The results of preliminary solubility trials showed that MGK 264 was insufficiently soluble to allow the preparation of solutions in dechlorinated tap water or acetone. Therefore, at test initiation, dispersions were established by the addition of appropriate weights of the test substance to approximately 15 mL of dechlorinated tap water. The mixtures were ultrasound treated for 10 minutes and further additions of dechlorinated water were made.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

A sample of activated sludge was obtained the day before the start of the test from Oakley Sewage Treatment Works, which treats predominantly domestic waste. In the laboratory, the sample was maintained under aerobic conditions until required.

The concentration of suspended solids in a homogenised sample was determined on the day of collection and immediately before the start of the test.

On the day of collection, aliquots (25 ml) of the activated sludge were filtered through dried and preweighed Whatman GFC filter papers which were then dried again at approximately 105°C for at least one hour, allowed to cool in a desiccator and reweighed. The mixed liquor suspended solids (MLSS) content of the activated sludge was then calculated.

Synthetic sewage (50 ml/L) was added to the sample of activated sludge and the mixture aerated overnight.

On the day of the test, the MLSS content of the sludge was determined and adjusted to 4 g/L by the addition of dechlorinated tap water. The pH of the sludge was also measured.

Test type:

static

Water media type:

other: The water used to prepare solutions of synthetic sewage and the reference substance was tap water that had been softened and treated by reverse osmosis and then purified to give a resistivity ≥ 18 MegOhm.cm.

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

N/A

Hardness:

Not Measured

Test temperature:

Initial = 18.4-19.6 °C
Final = 17.9-19.0 °C

pH:

Initial = 7.4-7.7
Final = 8.0-8.3

Dissolved oxygen:

Initial = 4.0-9.0
Final = 2.5-5.4
mg Oxygen/l

Salinity:

Not Measured

Conductivity:

Not Measured

Nominal and measured concentrations:

Nominal only. 1, 10 & 100 mg/L

Details on test conditions:

The prepared mixtures were aerated for three hours using a Pasteur pipette connected to a laboratory supply of oil-free compressed air (1 L/min).

Following the exposure period, a well-mixed sample of each mixture was transferred to a biochemical oxygen demand (BOD) bottle (capacity; 270 mL). The rate of oxygen consumption was measured, over a period of approximately ten minutes or until the dissolved oxygen concentration fell below 2 mg oxygen per L, using a Yellow Springs Instruments (YSI) dissolved oxygen meter, with temperature probe and self-stirring bottle probe, connected to a chart recorder. The pH and temperature of the samples were measured at the start and end of the test.

Reference substance (positive control):

yes

Remarks:

3,5- DICHLOROPHENOL

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Respiration rates decreased by 11, 4 and 1 % of the mean control rate in three mixtures containing the test item at a nominal concentration of 100 mg/I. The EC20, EC50 and EC80 of the test substance could not be calculated but these must be >100 mg/I.

Basis for effect:

other:

Details on results:

MGK 264 had no biologically significant inhibitory effect on the respiration rate of activated sludge at any of the concentrations employed in the test. Sludge respiration rates were decreased by 11, 4 and 1% of the mean control rate in three mixtures containing MGK 264 at a nominal concentration of 100 mg/L. The EC20, EC50 and EC80 of the test substance could not, therefore, be calculated but these must be greater than 100 mg/L, the highest level tested.

Results with reference substance (positive control):

Sludge respiration rates were progressively reduced in the presence of increasing concentrations of 3,5-DCP. The three-hour 50% effect concentration (EC50) for 3,5-DCP was calculated by the Moving Average method to be 8.4 mg/L (95% confidence limits 6.4 - 10.7 mg/L).

The specific respiration rate of the control culture established at the end of the test (21.4 mg02/g/h) was I 04% of the rate of that established at the start (20.5 mg02/g/h).

These results show that the test was valid and that the sample of activated sludge employed was sensitive to inhibition.

Reported statistics and error estimates:

The EC20, EC50 and EC80 of the test substance could not be calculated but these must be greater than 100 mg/L, the highest level tested.

Validity criteria fulfilled:

yes

Conclusions:

MGK 264 had no biologically significant inhibitory effect on the respiration rate of activated sludge at any of the concentrations employed in the test. Sludge respiration rates were decreased by 11, 4 and 1% of the mean control rate in three mixtures containing MGK 264 at a nominal concentration of 100 mg/L. The EC20, EC50 and EC80 of the test substance could not, therefore, be calculated but these must be greater than 100 mg/L, the highest level tested.

Executive summary:

The effect of MGK 264 on the respiration rate of activated sludge was assessed by the methods detailed in EC Directive 88/302, 'Biodegradation - Activated Sludge Respiration Inhibition test' and OECD Test Guideline 209, 'Activated Sludge, Respiration Inhibition test'.

 

Samples of activated sludge (suspended solids 1.6 g/L), fed with synthetic sewage, were exposed to the test substance at nominal concentrations of 1, 10 and 100 mg/L for three hours. Single mixtures were prepared at 1 and 10 mg/L and the highest level was prepared in triplicate. Their rates of oxygen consumption were determined and compared with those of controls, containing activated sludge and synthetic sewage alone, which were established at the beginning and end of the culture series. The reference inhibitor 3,5 -dichlorophenol (3,5 -DCP) was employed at 3, 10 and 32 mg/L, as a positive control.

 

The specific respiration rate of the control culture established at the end of the test series (21.4 mg Oxygen/g/h) was 104% of the rate of that established at the start (20.5 mg oxygen /g/h).

The three-hour 50% effect concentration (EC50) for 3,5 -DCP was calculated to be 8.4 mg/L (95% confidence limits 6.4 - 10. 7 mg/L). These results show that the test was valid and that the sample of activated sludge employed was sensitive to inhibition.

 

MGK 264 Insecticide Synergist had no biologically significant inhibitory effect on the respiration rate of activated sludge at any of the concentrations employed in the test. Sludge respiration rates in mixtures exposed to MGK 264 Insecticide Synergist were decreased, at most, by 11 % in one replicate at 100 mg/I. The EC20, EC50 and EC80 of the test substance could not, therefore, be calculated but these must be greater than 100 mg/I, the highest level tested.

Description of key information

The effect of MGK 264 on the respiration rate of activated sludge was assessed by the methods detailed in EC Directive 88/302, 'Biodegradation - Activated Sludge Respiration Inhibition test' and OECD Test Guideline 209, 'Activated Sludge, Respiration Inhibition test'.

 

Samples of activated sludge (suspended solids 1.6 g/L), fed with synthetic sewage, were exposed to the test substance at nominal concentrations of 1, 10 and 100 mg/L for three hours. Single mixtures were prepared at 1 and 10 mg/L and the highest level was prepared in triplicate. Their rates of oxygen consumption were determined and compared with those of controls, containing activated sludge and synthetic sewage alone, which were established at the beginning and end of the culture series. The reference inhibitor 3,5 -dichlorophenol (3,5 -DCP) was employed at 3, 10 and 32 mg/L, as a positive control.

 

The specific respiration rate of the control culture established at the end of the test series (21.4 mg oxygen/g/h) was 104% of the rate of that established at the start (20.5 mg oxygen/g/h). The three-hour 50% effect concentration (EC50) for 3,5 -DCP was calculated to be 8.4 mg/L (95% confidence limits 6.4 - 10. 7 mg/L). These results show that the test was valid and that the sample of activated sludge employed was sensitive to inhibition.

 

MGK 264 had no biologically significant inhibitory effect on the respiration rate of activated sludge at any of the concentrations employed in the test. Sludge respiration rates in mixtures exposed to MGK 264 were decreased, at most, by 11% in one replicate at 100 mg/L. The EC20, EC50 and EC80 of the test substance could not, therefore, be calculated but these must be greater than 100 mg/L, the highest level tested.

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

EC10 or NOEC for microorganisms:

100 mg/L

Additional information

100 mg/L was the highest concentration tested. The NOEC was classed as being >100.0 mg/L.