EPOFLOC L-1R

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:

23rd January 2014 to 13th February 2014

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

Deviations:

yes

Remarks:

- the temperature in the definitive test exceeded the required range by 0.5°C outlined in the study plan. The maximum temperature recorded was 22.5°C (required range from study plan = 20±2°C)

GLP compliance:

yes

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source: Cambridge Sewage Treatment Works, Cowley Road, Cambridge

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

10 to 15 minutes

Hardness:

No data

Test temperature:

21 - 22.5°C

pH:

7.89 was recorded for 1000 mg/l therefore no adjustment required and measurements for lower test concentrations not necessary.

Dissolved oxygen:

Controls: 0.19 - 8.37
Test 10 to 1000 mg/l: 1.04 - 9.13
(See attached report for full results)

Nominal and measured concentrations:

- Preliminary test: 0 (Control) 10, 100, 1000 mg/l
- Main test: 0 (Control), 10, 32, 100, 320, 1000 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: 500ml flasks with magnetic stirrer bars and aeration and glass BOD bottles for Dissolved Oxygen measurement
- Type: closed
- Material, size, headspace, fill volume: 300ml (final test volumes)
- Aeration: Yes
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 6 (in total)
- Amount of test substance per vessel (not controls): 3 ml of 3.2 g/l test stock
- Amount of synthetic sewage feed (all vessels): 9.6 ml
- Amount of 3.75 g/l microbial inoculum (all vessels): 120 ml

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: High purity deionised water
- See attached report for details of prepared medium

OTHER TEST CONDITIONS
- Adjustment of pH: Only required for reference stock (1.0 g/1 3,5 - Dichlorophenol) - adjusted to pH 7.37.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): 3h EC20, EC50 and EC80

PRELIMINARY TEST
- Range finding study: Yes
- Test concentrations: 0 (Control), 10, 100, 1000 mg/l
- Results used to determine the test concentrations and validate the conditions for the definitive study:
Mean control respiration rate = 29.16 mg O2/hour
Mean control respiration rate as mg O2/g dry weight activated sludge/hour = 19.44
Coefficient of variation for controls = 3.49%

MAIN TEST
- Test concentrations: 0 (Control), 10, 32, 100, 320, 1000 mg/l

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (3,5-DCP)

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

31.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 95% confidence limits: 28.5 - 56.0 mg/l

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

8.86 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 95% confidence limits: 7.07 - 12.3 mg/l

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? Yes

- Relevant effect levels:
3 hour EC20 = 1.06 mg/l (95% confidence limits: 1.05 - 1.07 mg/l)
3 hour EC50 = 4.60 mg/l (95% confidence limits: 4.52 - 4.69 mg/l)
3 hour EC80 >18 mg/l

Reported statistics and error estimates:

EC values were calculated by linear interpolation in ToxCalcTM Version 5.0.

- Test type: Activated Sludge Respiration Test

- Test period: 23 to 24 January 2014 - preliminary test

                       12 to 13 February 2014 - definitive test

- Test concentrations: 10, 100 and 1000 mg/l - preliminary test; 10, 32, 100, 320 and 1000 mg/l - definitive test (Reference substance (3,5-DCP): 2, 6 and 18 mg/l for both preliminary test and definitive test).

- Definitive test results:

 

3 hour exposure period	ECx values (mg/l)
	EC20	EC50	EC80
Test substance	8.86 (7.07 - 12.3)	31.8 (28.5 - 56.0)	>1000
3,5-DCP (Reference)	1.06 (1.05 - 1.07)	4.60 (4.52 - 4.69)	>18

Validity criteria fulfilled:

yes

Conclusions:

- Epofloc L-1R causes respiration inhibition to microorganisms although the inhibition is significantly less than the reference substance.
- The 3-hour EC50 was determined to be 31.8 mg/l during the definitive test.
- The validity criteria were all met for the definitive test.

Description of key information

The 3h EC50 was determined to be 31.8 mg/l

Key value for chemical safety assessment

EC50 for microorganisms:

31.8 mg/L