Fructofuranosidase, β-

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data based on the inhibition control of a ready biodegradability study. This approach is in accordance with the Guidance on information requirements and chemical safety assessment (Chapter R.7b: Endpoint specific guidance, ECHA 2017).

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD 301E

GLP compliance:

yes (incl. QA statement)

Test organisms (species):

activated sludge

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Domestic waste water treatment plant : ARA Ergolz II, Füllinsdorf, Switzerland
- Preparation of inoculum for exposure: The sludge was washed three times with tap water and an amount corresponding to 4g/L dry material (± 10%) was mixed with Sörensen buffer solution pH7 and then aerated prior to incubation. An amount of 0.5 mL sludge (filtered over cotton wool) was added to 1000 mL test medium.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

28 d

Details on test conditions:

TEST CONDITIONS
- Composition of medium: according to OECD Guideline No. 301 E
- Test temperature: 19.7 - 21.5°C
- Continuous darkness: yes

SAMPLING
- Sampling frequency: day 0 (treatment day) , 7, 14, 21, 27 and 28
- Sampling method: Per sampling interval, two flasks of the samples containing the test article or the reference compound, one flask of the inoculum blank and one flask of the toxicity control were taken and analysed for DOC in triplicate.

Reference substance (positive control):

yes

Remarks:

aniline

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 45 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Result of toxicity control from ready biodegradability test

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 25.65 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Remarks:

active enzyme protein

Basis for effect:

other: Result of toxicity control from ready biodegradability test

Results with reference substance (positive control):

The reference compound aniline reached complete biodegradation during the first seven exposure days. At the end of the test, aniline was readily biodegraded by an average of 95.1%.

Description of key information

NOEC (28 d):≥25.65 mg aep/L (OECD 301F; read-across)

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

25.65 mg/L

Additional information

Studies investigating the toxicity of β-fructofuranosidase to microorganisms are not available. An inhibition of the activity of activated sludge organisms is not expected based on the readily biodegradability of the substance. The enzyme β-fructofuranosidase is expected to be readily biodegradable based on read-across data, available for the sourceα-amylase. In the available test, conducted according to OECD guideline 301F, a degradation rate of 99% after 28 days at a test substance concentration of 44 mg/L was determined. Based on the results of the ready biodegradability study, no inhibition of the activity of activated sludge microorganisms by the source substance is expected. It is assumed that these conclusions can also be applied to the target substance. Hence, based on the available information, β-fructofuranosidase is not expected to be toxic to aquatic microorganisms.

Since no studies on the toxicity to aquatic microorganisms are available, the ready biodegradability study is used to derive a NOEC for the toxicity to aquatic microorganisms. If a compound degrades well in a ready biodegradability test, or does not inhibit the degradation of a positive control at a certain concentration, this concentration can be used as a NOEC value. This approach is in accordance with the Guidance on information requirements and chemical safety assessment (Chapter R.7b: Endpoint specific guidance, ECHA 2017).

The available ready biodegradability study according to OECD 301F (read-across) includes a toxicity control, which contains 25.65 mg/L active enzyme protein and 26 mg/L of the reference material aniline. The reference compound aniline reached complete biodegradation during the first seven exposure days. At the end of the test, aniline was readily biodegraded by an average of 95.1%. The test substance was degraded by 99% after 28 days. Therefore, the substance is expected to be not toxic to aquatic microorganisms in the toxicity control and the test item concentration of 25.65 mg/L can be used as NOEC.