4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disiladecane

Toxicity to microorganisms

Link to relevant study record(s)

Reference

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:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

DIN 38412-8 (Pseudomonas Zellvermehrungshemmtest)

Version / remarks:

(March 1991)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on test solutions:

Test media were prepared by vigorous stirring overnight plus two hours separation.

Test organisms (species):

Pseudomonas putida

Details on inoculum:

TEST ORGANISM

- Common name: Pseudomonas putida

- Strain: DSM 50026 (lyophilisate, obtained March 1993).

- Source: MIGULA stock culture

Stock cultures of Pseudomonas putida were streaked on nutrative media for stock cultures, incubated overnight at 25 ˚C and kept at 4 ˚C. Bacteria were transferred to fresh media on a monthly basis. These cultures were used as original cultures in the present test. Prior to the main test, the bacteria strain was adapted to liquid medium by cultivating in nutritive solution for pre-cultures. After incubating overnight at 21 ˚C, the turbidity of the bacterial suspension was measured and adjusted to TE/F 50 by addition of medium for pre-culture. This suspension was used as inoculum for the test pre-culture.

A test pre-culture with an initial turbidity of ca. TE/F 5 was prepared and incubated for 7h at 20 - 22 ˚C. The turbidity was measured and adjusted to ca. TE/F 10 by addition of test medium. This suspension was used as inoculum for the test culture.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

16 h

Test temperature:

20 - 22 ˚C

pH:

not stated.

Nominal and measured concentrations:

700, 2850, 4250, 5650, 8000 mg/l (nominal) plus control (0 mg/l)

Details on test conditions:

TEST SYSTEM

- Test vessel: 100 ml Erlenmeyer flasks

- No. of vessels per concentration (replicates): performed in triplicate

- No. of vessels per control (replicates): performed in triplicate

- No. of vessels per vehicle control (replicates): performed in triplicate

TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Purified water was used for all solutions and media

OTHER TEST CONDITIONS

- Photoperiod: none

- Light intensity: dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Turbidity

TEST CONCENTRATIONS

- Range finding study
- Test concentrations: 10 g/l, 1.0 g/l (plus Tween 80) and 100 mg/l

Reference substance (positive control):

no

Key result

Duration:

16 h

Dose descriptor:

EC50

Effect conc.:

>= 8 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: cell multiplication

Results with reference substance (positive control):

Within the last representative reference test (21-23 July 1993) with 3,5-dichlorophenol tested under the same conditions gave EC50 and EC10 values of 17.3 mg/l and 6.5 mg/l respectively. This EC50 is in keeping with the interlaboratory comparison results of 21.4 ± 4.91 mg/l though the EC10 is lower than the interlaboratory comparison of 13.7 ± 4.36 mg/l.

Validity criteria fulfilled:

yes

Remarks:

mean biomass in controls increased by more than 100-fold. A recent reference test using 3,5-dichlorophenol tested under the same conditions gave typical inhibitory EC50 results.

Conclusions:

A NOEC of ≥8000 mg/l (nominal, highest concentration tested) was obtained for inhibition of cell multiplication in a P. putida cell multiplication inhibition test according to Guideline DIN 38412 and in compliance with GLP. The result is considered reliable.

Description of key information

Short-term toxicity to microorganisms: 16 hour EC50 >8000 mg/L and NOEC ≥8000 mg/L (nominal) (highest concentration tested) (DIN 38412 part 8), based on inhibition of cell multiplication in P. putida.

Key value for chemical safety assessment

EC50 for microorganisms:

8 000 mg/L

EC10 or NOEC for microorganisms:

8 000 mg/L

Additional information

A 16-hour EC50 value of >8000 mg/L and NOEC of ≥8000 mg/L (nominal) (highest concentration tested) have been determined for the effects of 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disiladecane (CAS 16068-37-4) on cell multiplication of Pseudomonas putida. In view of the test media preparation method it is likely that the test organisms were exposed to a mixture of the parent substance and its hydrolysis products, which could have included some cross-linked products.