2,4,7,9-Tetramethyldec-5-yne-4,7-diol, ethoxylated

Toxicity to microorganisms

Link to relevant study record(s)

Reference

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

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar toxicological properties because
- they are manufactured from similar precursors under similar conditions
- they share structural similarities with common functional groups: the substances start with an acetylene group as core structure; geminal hydroxyl groups on the alpha carbon atoms; distal to the geminal hydroxyl groups is an isobutyl group (methyl isopropyl); the target substance 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (1.3) is further functionalised with ethylene oxide and has an ethoxylation degree of 1.3; the source substance 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (3.8) has an ethoxylation degree of 3.8
- they have similar physicochemical properties and thus, show a similar toxicokinetic behaviour
- they are expected to undergo similar metabolism: oxidation of the terminal methyl groups to result in alcohol, aldehyde and finally the corresponding acid

Therefore, read-across from the existing toxicity, ecotoxicity, environmental fate and physicochemical studies on the source substances is considered as an appropriate adaptation to the standard information requirements of REACH regulation.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
see “Justification for read-across” attached to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
see “Justification for read-across” attached to IUCLID section 13

4. DATA MATRIX
see “Justification for read-across” attached to IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Test organisms (species):

activated sludge

Test type:

static

Water media type:

freshwater

Total exposure duration:

3 h

Test temperature:

20 +/- 1 °C

pH:

6.7-7.1

Details on test conditions:

Type: aquatic

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

ca. 680 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Validity criteria fulfilled:

yes

Conclusions:

The mean median inhibitory concentration of the substance to activated sludge respiration was in the range of 680 to 840 ppm. Because the limits of sample solubility may have been reached or exceeded at test temperature, the lower EC 50 may be more reliable.

Description of key information

30 min EC50 = 680 mg/L (OECD TG 209, activated sludge; read-across: 2,4,7,9-Tetramethyl-5-decyne-4,7-diol)

Key value for chemical safety assessment

EC50 for microorganisms:

680 mg/L

Additional information

Experimental data on toxicity to algae of 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (1.3) are not available. However, studies were conducted with the structurally related source substance 2,4,7,9-Tetramethyl-5-decyne-4,7-diol. A justification for read-across is attached to iuclid section 13.

 

In a respiration inhibition study according to OECD TG 209, the 30-minute EC50 of 2,4,7,9-Tetramethyl-5-decyne-4,7-diol to activated sludge respiration was 680 mg/L.

 

This 30 min EC50 obtained with the source substance of 2,4,7,9-Tetramethyl-5-decyne-4,7-diol is used for chemical safety assessment of the target substance 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (1.3).