Pyrrolo[3,4-c]pyrrole-1,4-dione, 3,6-bis(4-chlorophenyl)-2,5-dihydro-

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1990-01-22 to 1990-02-06

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP-study without analytical monitoring

Qualifier:

according to guideline

Guideline:

other: EEC L133, page 118-122 (30. May 1988)

Deviations:

yes

Remarks:

Instead of a centrifuged sludge a settled sludge was used. In addition, the substance was given directly to the medium (no stock solution).

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Activated sludge collected from the sewage treatment plant of CH-4153 Reinach on 1990-02-05. The preparation was carried out according to the method described in the guideline. The sludge was separated from the aqueous layer by settling instead of centrifugation.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20 ± 2°C

Nominal and measured concentrations:

Nominal concentrations:
Test substance: 3.35, 4.75, 10.85, 35.5 and 103.9 mg/L
Reference substance: 3.2, 10.0, 32.0 mg/L
The sludge concentration in the test bottles was 1.7 g/L.

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 ml BOD flasks with gas inlet
- Type: closed
- No. of vessels per concentration (replicates): 1
- No. of control vessels: 2
- Water: Dechlorinated drinking water
- Duration: 3 h
Nutrient solution: 16 g Peptone, 11 g Meat extract, 3.0 g Urea, 0.7 g NaCl, 0.4 g CaCl2 x 2 H2O, 0.2 g MgSO4 x 7 H2O, 2.8 g K2HPO4 were dissolved and made up to one liter of dechlorinated drinking water.

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 100 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):

- Relevant effect levels: EC50 (3h) = 16 mg/L (graphically determined)

Validity criteria fulfilled:

yes

Conclusions:

In an respiration inhibition test with aerobic bacteria, the substance did not affect the oxygen consumption up to a concentration of 103.9 mg/L.

Executive summary:

The substance toxicity to microorganisms was investigated with a test on inhibition of respiration (oxygen consumption) of aerobic bacteria.

Five concentrations (3.35, 4.75, 10.85, 35.5, 103.9 mg/L) were tested by adding the respective amount directly to the test medium, which contained 1.7 g/L activated sludge. Oxygen consumption was not inhibited at any concentration.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1990-01-22 to 1990-02-06

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP-study without analytical monitoring

Justification for type of information:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The read-across is performed between two forms of the same substance. The identities of the two forms are describe below.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The source form is 3,6-bis(4-chlorophenyl)-2,5-dihydropyrrolo[3,4-c]pyrrol-1,4-dione (EC-no. 401-540-3), referred to here as PR254. PR254 is an organic mono-constituent substance with a typical purity of > 99.5% (w/w). It does not contain any impurity relevant for classification or labelling of the substance. The target form is the nanoform of the source substance, referred to here as PR254 nanoform. As the source form, it has a typical purity of > 99.5% (w/w) and it does not contain any impurity relevant for classification or labelling of the substance. The PR254 nanoform is spheroidal with a pure polyhedral shape and is not surface-treated.

3. ANALOGUE APPROACH JUSTIFICATION
The two analogue forms have the same structure. Under ambient atmosphere, the specific surface energy of particles increases with decreasing particle size. Therefore, particle aggregate to reach an energy minimum. The driving forces are hydrogen bonds and van der Waals forces (π-π interaction). Substantial energy is required to disperse the PR254 nanoform aggregates to particles that fall under the nanoform definition.
PR254 was been tested extensively addressing information requirements of Annexes VII to IX without identifying any biological target. PR254 nanoform could potentially have biological targets due to the different particle size distribution, which would require processes capable of dispersing the aggregates, e.g. in aqueous milieu. However, both forms have been tested according to OECD Test Guideline 318, demonstrating that PR254 nanoform cannot be dispersed under the condition of the study, i.e. immediately after sonification re-forms aggregates. Also, PR254 aggregates to a large extent, but can be more easily dispersed than the nanoform. The experiments demonstrated that exposure in aqueous milieu will be primarily to aggregates, regardless of the PR254 form.
Therefore, it is concluded that both forms will behave identically in studies, in which they are applied under atmospheric conditions and/or in aqueous milieus, so that for the PR254 nano-form no specific biological targets need to be considered.
As both forms form non-dispersible aggregates in aqueous milieu, read-across of aquatic toxicity studies from the source to the target form is scientifically justified.

4. DATA MATRIX
The data matrix is included as Annex 1 in the assessment report ‘PR254 bulk nano analogue approach 210111’ attached here below under ‘Attached justification’.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: EEC L133, page 118-122 (30. May 1988)

Deviations:

yes

Remarks:

Instead of a centrifuged sludge a settled sludge was used. In addition, the substance was given directly to the medium (no stock solution).

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Activated sludge collected from the sewage treatment plant of CH-4153 Reinach on 1990-02-05. The preparation was carried out according to the method described in the guideline. The sludge was separated from the aqueous layer by settling instead of centrifugation.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20 ± 2°C

Nominal and measured concentrations:

Nominal concentrations:
Test substance: 3.35, 4.75, 10.85, 35.5 and 103.9 mg/L
Reference substance: 3.2, 10.0, 32.0 mg/L
The sludge concentration in the test bottles was 1.7 g/L.

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 ml BOD flasks with gas inlet
- Type: closed
- No. of vessels per concentration (replicates): 1
- No. of control vessels: 2
- Water: Dechlorinated drinking water
- Duration: 3 h
Nutrient solution: 16 g Peptone, 11 g Meat extract, 3.0 g Urea, 0.7 g NaCl, 0.4 g CaCl2 x 2 H2O, 0.2 g MgSO4 x 7 H2O, 2.8 g K2HPO4 were dissolved and made up to one liter of dechlorinated drinking water.

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 100 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):

- Relevant effect levels: EC50 (3h) = 16 mg/L (graphically determined)

Validity criteria fulfilled:

yes

Conclusions:

In an respiration inhibition test with aerobic bacteria, the substance did not affect the oxygen consumption up to a concentration of 103.9 mg/L.

Executive summary:

The substance toxicity to microorganisms was investigated with a test on inhibition of respiration (oxygen consumption) of aerobic bacteria.

Five concentrations (3.35, 4.75, 10.85, 35.5, 103.9 mg/L) were tested by adding the respective amount directly to the test medium, which contained 1.7 g/L activated sludge. Oxygen consumption was not inhibited at any concentration.

Description of key information

In an respiration inhibition test with aerobic bacteria, the substance did not affect the oxygen consumption up to a concentration of 103.9 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

103.9 mg/L