Reaction mass of 3-(3,3-dimethyl-2,3-dihydro-1H-inden-5-yl)propanal and 3-(1,1-dimethyl-2,3-dihydro-1H-inden-5-yl)propanal and 3-(1,1-dimethyl-2,3-dihydro-1H-inden-4-yl)propanal

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:

2000-03-16

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

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 1999-09-22. Date of signature: 1999-12-21

Specific details on test material used for the study:

No additional information

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)

- Method: 100mg/l test solution was prepared by direct addition of the test substance in the test vessel with a micropipette

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Preparation of inoculum for exposure: the inoculum was left to settle and the supernatant rejected. It was then filtered (to remove the biggest particles) and washed with dechlorinated water. The concentration of sludge (6.56g/l) was then adjusted to 4 g/l by addition of the appropriate volume of dechlorinated water.

Test type:

static

Water media type:

freshwater

Total exposure duration:

3 h

Post exposure observation period:

The oxygen concentration was determined for a period of approximately 10 minutes

Details on test conditions:

TEST SYSTEM
- Test vessel: test flasks

- Aeration: air was bubbled through each solution at the rate of 0.5 to 1 l/min until the start of oxygen concentration measurements

- No. of vessels per concentration (replicates): 1

- No. of vessels per control (replicates): 1


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: dechlorinated tap water

TEST CONCENTRATIONS

- Test concentrations: 1, 3.16, 10, 31.6, 100mg/l

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.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

The difference between the two controls was below 15%; the validity criteria of the guideline were fulfilled.

Results with reference substance (positive control):

The EC50 of the reference substance 15 mg/l. The EC50 was between 5 and 30mg/l; the validity criteria of the guideline were fulfilled.

Table 1: Respiration rate

	Concentration (mg/l)	Respiratory rate (mg O2l^-1h^-1)	Percent inhibition (%)
Control 1	0	42
Control 2	0	44
Reference Substance	4	42	2.3
	12	21	51.2
	36	9	79.1
Test Substance	1	Not determined
	3.16	Not determined
	10	Not determined
	31.6	Not determined
	100	44	0

Validity criteria fulfilled:

yes

Conclusions:

A 3 hour EC50 of >100 mg/l was determined in a well conducted study according to an appropriate test protocol and in compliance with GLP.

Executive summary:

The effect of test substance on the respiration rate of activated sludge was investigated after a contact time of 3 h,according to OECD Guideline 209 with GLP statement.

Group of test and reference solutions and controls were set up as follows:

- two controls containing inoculum at 1.6 g/L,

- five test concentrations containing the test substance at 1, 3.16, 10, 31.6 and 100 mg/L and inoculum at 1.6 g/L,

- three reference concentrations containing the reference substance (3,5 -Dichlorophenol) at 4, 12 and 36 mg/L and inoculum at 1.6 g/L.

The respiration rate of the test solution at the highest concentration (100 mg/L) was equivalent to the respiration rate of the first control (i.e. these rates were within 15% of each other). Therefore, the oxygen consumption rate of the four other test solutions (1 to 31.6 mg/L) was not determined. Also, as the difference between the two controls was below 15% and the EC50 of the reference substance was between 5 and 30 mg/L (determined at 15 mg/L, 95% CL = 13 -18 mg/L), the test was considered valid.

In conclusion, under the experimental conditions, the 3h-EC50 of the test substance is > 100 mg/L for activated sludge. The test substance should be considered as non-toxic for the microorganisms in a water treatment plant.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
[further information is included as attachment to Iuclid section 13]

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar physicochemical, (eco)toxicological and environmental fate properties because of their composition similarity.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The target and the source substances are reaction mass, composed of three and two dimethylindanylpropanal isomers, respectively.

3. ANALOGUE APPROACH JUSTIFICATION
In the present case, the stereoisomerism is not expected to significantly influence the ecotoxicity of both substances. This statement is supported by the fact that no existing QSAR models differentiate both isomers for the endpoint of concern. Hence, it is considered suitable and scientifically justified to read-across the data between the two substances to fill the toxicity to microorganisms endpoint in the present dossier. Therefore, based on the considerations above, it can be concluded that the result of the ASRIT study conducted with the source substance is likely to predict the properties of the target substance and is considered as adequate to fulfil the information requirement of Annex VIII, 6.1.7.

4. DATA MATRIX
See attached document in Iuclid section 13.

Reason / purpose for cross-reference:

read-across source

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

Validity criteria fulfilled:

not applicable

Conclusions:

According to the experimental study performed on the source substance, the target substance is expected to have a 3h-EC50 value >100 mg/L for activated sludge. The target substance is considered non-toxic for the microorganisms in a water treatment plant.

Executive summary:

No activated sludge respiration inhibition test is available on the target substance, therefore good quality data for a related source substance have been read across for this endpoint. The target substance is a Reaction mass of 3 -(3,3-dimethyl-2,3-dihydro-1H-inden-5-yl)propanal and 3-(1,1-dimethyl-2,3-dihydro-1H-inden-5-yl)propanal and 3-(1,1-dimethyl-2,3-dihydro-1H-inden-4-yl)propanal. Similarly, the source substance is mainly a combinaison of 3-(3,3-dimethyl-2,3-dihydro-1H-inden-5-yl)propanal and 3-(1,1-dimethyl-2,3-dihydro-1Hinden-5-yl)propanal. Both substances are multi-constituent substances containing isomers of alkyl indane naphthenic aromatic ring. The absence of the 3-(1,1-dimethyl-2,3-dihydro-1H-inden-4-yl)propanal isomer from the reaction mass in the source study is not expected to affect the outcome of the result for the target material. It's therefore considered appropriate to read-across available data to the target/registered substance.

According to the experimental study performed on the source substance, the target substance is expected to have a 3h-EC50 value >100 mg/L for activated sludge. The target substance is considered non-toxic for the microorganisms in a water treatment plant.

Description of key information

Read-across, OECD Guideline 209, GLP, key study, validity 1:

3h-EC50 > 100 mg/L for activated sludge

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

Additional information

No activated sludge respiration inhibition test is available on the target substance, therefore good quality data for a related source substance have been read across for this endpoint. The target substance is a Reaction mass of 3 -(3,3-dimethyl-2,3-dihydro-1H-inden-5-yl)propanal and 3-(1,1-dimethyl-2,3-dihydro-1H-inden-5-yl)propanal and 3-(1,1-dimethyl-2,3-dihydro-1H-inden-4-yl)propanal. Similarly, the source substance is mainly a combinaison of 3-(3,3-dimethyl-2,3-dihydro-1H-inden-5-yl)propanal and 3-(1,1-dimethyl-2,3-dihydro-1Hinden-5-yl)propanal. Both substances are multi-constituent substances containing isomers of alkyl indane naphthenic aromatic ring. The absence of the 3-(1,1-dimethyl-2,3-dihydro-1H-inden-4-yl)propanal isomer from the reaction mass in the source study is not expected to affect the outcome of the result for the target material. It's therefore considered appropriate to read-across available data to the target/registered substance.

According to the experimental study performed according to the OECD Guideline 209 with GLP statement on the source substance, the target substance is expected to have a 3h-EC50 value >100 mg/L for activated sludge. The target substance is considered non-toxic for the microorganisms in a water treatment plant.