Registration Dossier

Ecotoxicological information

Toxicity to microorganisms

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Toxicity to microorganisms: 3hr EC50 >1000 mg/l; NOEC >=1000 mg/l (OECD 209)

Key value for chemical safety assessment

Additional information

Under the conditions of the OECD TG 209 test, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane was not toxic to waste water (activated sludge) bacteria up to and including a loading rate of 1000 mg/l (NOEC). The EC50 exceeded a loading rate of 1000 mg/l.

The registration substance has a purity of >80% Vi4-D4, with <15% 2,4,6,8,10-pentamethyl-2,4,6,8,10-pentavinylcyclopentasiloxane (Vi5-D5; CAS 17704-22-2; Impurity 1) and <10% 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane (Vi3-D3; CAS 3901-77-7; Impurity 2) present as impurities. After due consideration of the properties, the presence of these impurities is not expected to affect the overall hazard profile of the substance. Vi5-D5 and D5 are within the Reconsile Siloxane Category of substanceswithin which, in general, the substances exhibit no evidence of significant toxicity to microorganisms. Table 7.1.7 presents microorganism toxicity data available for substances within the Siloxane Category. Vi3-D3 and D3 do not fall within the Category definition, however the substances are structurally similar, and a study with D3 concludes that no evidence of significant toxicity to STP organisms.It is therefore considered valid to read-across the results for D5 and D3.Additional information is given in a supporting report (Peter Fisk Associates, 2017)attached in Section 13 of the IUCLID 6 dossier.

Read-across studies are in place as supporting studies, to consider the properties of the impurities. Data for Vi5-D5 are read-across from decamethylcyclopentasiloxane D5 (CAS 541-02-6), data for Vi3-D3 are read-across from hexamethyltrisiloxane D3 (CAS 541-05-9). An ASRI 3hr EC50of >2000 mg/l was determined for D5. An ASRI EC50>100 mg/l was determined for D3.

Table: Microorganism toxicity data available for substances within the Siloxane Category

CAS

Name

Result: E(I)C50(mg/l)

Result: NOEC (or EC10/ EC20) (mg/l)

Guideline Number

Test method

Duration

Reliability

000540-97-6

Dodecamethylcyclohexasiloxane

>100 mg/l

 

OECD 209

ASRI

3hr

1a

000541-02-6

Decamethylcyclopentasiloxane

>2000 mg/l

 

C11

ASRI

3hr

1a

000141-62-8

Decamethyltetrasiloxane

>100 mg/l

 

OECD 209

ASRI

3hr

1a

352230-22-9

Siloxanes and Silicones, di-Ph, Ph (trimethylsilyl)oxy

>1000 mg/l

≥1000 mg/l

OECD 209

ASRI

3hr

1a

002627-95-4

1,1,3,3-tetramethyl-1,3-divinyldisiloxane

>1000 mg/l

≥1000 mg/l

OECD 209

ASRI

3hr

1a

002554-06-5

2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane

>1000 mg/l

≥1000 mg/l

OECD 209

ASRI

3hr

1a

070131-69-0

Silsesquioxanes, Phenyl

>1000

≥1000

OECD 209

ASRI

3 hr

1a

099363-37-8

dimethyl, methyl(3-aminopropyl) siloxane, trimethylsiloxy-terminated

> water soluble fraction

≥ water soluble fraction

OECD 209

ASRI

3hr

1a

071750-79-3

dimethyl, (aminoethylaminopropyl)methyl siloxane, trimethylsiloxy-terminated

> water soluble fraction

≥ water soluble fraction

OECD 209

ASRI

3hr

1a