Dichlorotricyclo[8.2.2.24,7]hexadeca-1(12),4,6,10,13,15-hexaene, mixed isomers

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

GLP compliance:

yes

Test material

Test material information

1

Reference substance name:

Dichlorotricyclo[8.2.2.24,7]hexadeca-1(12),4,6,10,13,15-hexaene, mixed isomers

EC Number:

249-236-8

EC Name:

Dichlorotricyclo[8.2.2.24,7]hexadeca-1(12),4,6,10,13,15-hexaene, mixed isomers

Cas Number:

28804-46-8

Molecular formula:

C16H14Cl2

IUPAC Name:

Reaction product of tricyclo[8.2.2.24,7]hexadeca-1(12),4,6,10,13,15-hexaene with chlorine

Test material form:

solid: granular

Test solutions

Vehicle:

no

Details on test solutions:

The test item concentrations were prepared by directly weighing the test item into each test flask, since the test item is not soluble in water.

Test organisms

Test organisms (species):

activated sludge

Study design

Water media type:

freshwater

Total exposure duration:

3 h

Test conditions

Reference substance (positive control):

yes

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Effect concentrations 2

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Results with reference substance (positive control):

The EC50 values of 3,5-dichlorophenol were in compliance with the validity range indicated by the reference guidelines (EC50: 2 - 25 mg/L) and it was equal to 11.5 mg/L (LCL, Lower Confidence Level: 9.7 mg/L - UCL, Upper Confidence Level: 13.1 mg/L)

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Based on the obtained results, the EC50 value after 3 hours of incubation for test item was assessed to be higher than 1000.0 mg/L and the NOEC value was calculated as equal to the nominal concentration of 1000.0 mg/L.

Executive summary:

The toxicity of test itemDPX-C (Di-Cloro-Di-p-Xililene)to activated sludge was assessed in a respiration inhibition study according to:

 

-       OECD Guideline No. 209, “Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation)”, 2010.

-       EU Commission Directive EC 440/2008, C.11.

 

For this purpose, aerobic activated sludge collected from the aeration tank of the civil wastewater treatment plant “BRIANZACQUE” was incubated for 3 hours in presence of different concentrations of test item, as provided by OECD Guideline No. 209/2010.

In addition, two untreated negative controls were incubated under the same conditions.

 

Oxygen consumption was measured using a portable oximeter and the inhibitory effect of the test item was expressed as percentage inhibition of the mean respiratory rate compared to negative controls.

 

Firstly, a range-finding test at three different concentrations of test item, namely 10.0 mg/L, 100.0 mg/L and 1000.0 mg/L as test item,were tested.

Since no significant effect was shown at the highest tested concentration of test item compared with the negative controls,a definitive test was unnecessary, buttwo additional replicates of 1000.0 mg/L were prepared, as provided by OECD Guideline No. 209/2010.

 

Results are related to the nominal concentrations ofDPX-C (Di-Cloro-Di-p-Xililene).

 

Moreover three abiotic controls were tested to measure the abiotic oxygen consumption. After 3 hours of exposure, abiotic controls did not show any significant oxygen consumption.

 

In order to check the normal sensitivity of the batch of activated sludge, 3,5-dichlorophenol was used as reference item. For this purpose three nominal concentrations were tested, 1.0 mg/L, 5.0 mg/L and 25.0 mg/L, respectively.

The EC₅₀values of 3,5-dichlorophenol were in compliance with the validity range indicated by the reference guidelines (EC₅₀: 2 - 25 mg/L) and it was equal to 11.5 mg/L (LCL, Lower Confidence Level: 9.7 mg/L - UCL, Upper Confidence Level: 13.1 mg/L).

 

Thecoefficient of variationof oxygen consumption rates in negative control replicates was 3.5% after 3 hours, thus complying with the validity criterion that requires a maximum coefficient of variation of 30% at the end of the test.

 

In the negative controls specific respiration rates (R_s) mean value was equal to 20.3 mg O₂/g sludge/h after 3 hours, greater than the minimum value provided by OECD guideline No. 209, 20 mg oxygen per one gram of activated sludge (dry weight) in an hour.

 

Based on the obtained results, the EC₅₀value after 3 hours of incubation for test item was assessed to be higher than 1000.0 mg/L and the NOEC value was calculated as equal to the nominal concentration of 1000.0 mg/L.

 

During the test period temperature was in the range 19.8 – 20.1 °C.