7-methyl-2H-benzo-1,5-dioxepin-3(4H)-one

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

August 11 to September 12, 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

This study was performed according to OECD Guideline 301F with GLP statement. All validity criteria were fulfilled.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Swiss GLP compliance programme (inspected on March 31-April 01, 2005 / signed on June 2005)

Specific details on test material used for the study:

- Physical state: White crystals

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (City of Geneva, Peney-Dessous) was used.
The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept
aerobic until being used on the same day.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

32 d

Remarks on exposure duration:

Exposure duration of the biodegradation study

Hardness:

No data

Test temperature:

22°C

pH:

The pH is measured and if necessary adjusted to 7.4 ± 0.2 with phosphoric acid or potassium hydroxide

Dissolved oxygen:

No data

Salinity:

Not applicable

Conductivity:

No data

Nominal and measured concentrations:

100 mg/L

Details on test conditions:

The toxicity of the test substance for the inoculum was checked in the biodegradation study. A pair of flasks of the volumetric respirometer was filled with mineral medium + test substance (100 mg/I) + reference substance (Benzoic acid, sodium salt 100 mg/l) + inoculum and their respirations were recorded according to the OECD Guideline 301F. If they are lower than those of the flasks containing mineral medium + reference substance ( 100 mg/l) + inoculum, the test substance can be assumed to be inhibitory to the inoculum used.

Reference substance (positive control):

yes

Remarks:

benzoic acid, sodium salt 100 mg/L

Key result

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: O2 consumption

Details on results:

The curves obtained with the reference substance alone and with the test substance + reference substance showed no toxic effect of the test substance to the micro-organisms at the test concentration (100 mg/L).

Results with reference substance (positive control):

See table in "Any other information on results incl. tables".

Reported statistics and error estimates:

None

Table 6.1.7/1: Biodegradability of the reference substance and test substance toxicity control

	Days	5	7	14	21	28	32
BOD sludge	1st flask 2nd flask Mean	7.0 4.0 5.5	11.0 8.0 9.5	17.0 17.0 17.0	25.0 26.0 25.5	28.0 29.0 28.5	28.0 29.0 28.5
BOD reference substance	1st flask 2nd flask Mean	127.0 135.0 131.0	143.0 150.0 146.5	161.0 168.0 164.5	173.0 179.0 176.0	181.0 187.0 184.0	181.0 187.0 184.0
% biodegradation reference substance	1st flask 2nd flask Mean	73 78 75	80 84 82	86 91 89	89 92 90	92 95 93	92 95 93
BOD refer. + test substance (toxicity control)	1st flask 2nd flask Mean	148.0 162.7 155.3	157.4 172.7 165.0	168.7 186.8 177.8	176.0 197.8 186.9	182.1 205.8 193.9	183.1 206.8 194.9

BOD: Biological Oxygen Demand, mg O2/L, adjusted to nominal concentrations.

As BOD values of the toxicity control are not lower than those of the flasks containing mineral medium + reference substance ( 100 mg/l) + inoculum (BOD reference substance), the test substance can be assumed to be not toxic to the inoculum used.

Validity criteria fulfilled:

not applicable

Conclusions:

Under the test conditions, test substance should be regarded as not toxic to microorganisms up to 100 mg/L.

Executive summary:

The toxicity effect of the test substance to microorganisms has been determined in the Manometric Respirometry Test according to the OECD Guideline No. 301F, EU Method C.4 -D with GLP compliance, in a toxicity control. A nominal concentration of test substance (100 mg/L) was introduced in the system. The results obtained with the reference substance alone (benzoic acid, sodium salt) and with the test substance + reference substance show no toxic effect of the test substance to the micro-organisms at the test concentration (100 mg/L).

In conclusion, test substance should be regarded as not toxic to microorganisms up to 100 mg/L, under the test conditions.

Description of key information

OECD Guideline 301F, EU Method C.4-D, GLP, Weight of evidence, validity 1:

Not toxic to microorganisms up to 100 mg/L

Additional information

No activated sludge respiration inhibition test is available on the registered substance. However, a toxicity control was performed in the biodegradation study (Givaudan, 2005) performed on the registered substance and can be used to fulfil this endpoint.

The toxicity effect of the test substance to microorganisms has been determined in the Manometric Respirometry Test according to the OECD Guideline No. 301F, EU Method C.4 -D with GLP compliance, in a toxicity control. A nominal concentration of test substance (100 mg/L) was introduced in the system. The results obtained with the reference substance alone (benzoic acid, sodium salt) and with the test substance + reference substance shows no toxic effect of the test substance to the micro-organisms at the test concentration (100 mg/L).

In conclusion, test substance should be regarded as not toxic to microorganisms up to 100 mg/L, under the test conditions.