5-methylheptan-3-one oxime

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15.10.1996 to 13.11.1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

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:

not specified

Principles of method if other than guideline:

Inhibition control in Ready Biodegradability test.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Lot No.: 263992
Purity: 96.3% (GC, sum of 2 isomers)

Analytical monitoring:

not required

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (City of Geneva, Aire) 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:

28 d

Nominal and measured concentrations:

100 mg/L

Reference substance (positive control):

yes

Remarks:

Aniline

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Comparison of respiration of flasks containing test chemical + positive control and flasks containing positive control only

Details on results:

The curves obtained with Aniline alone and with STEMONE+Aniline show no significant toxic effect of STEMONE on the microorganisms at the test concentration (100mg/L) - see illustration section.

RESULTS

 Oxygen uptakes, as read on the SAPROMAT meters, are corrected:

-         By deducting the basic oxygen uptake of sludge (flasks 2/5 and 2/6)

-         proportionally to account for the differences between actual and measured concentrations of the test and reference substances.

 

In flasks containing aniline alone, pH remained roughly at the same level: this suggests that the final form of nitrogen is partly one of the acid forms NO2or NO3 –and partly the alkaline ion NH4 +.The Theoretical Oxygen Demand (ThOD) corresponding to NO3 -was used for the calculation of the biodegradation rates of aniline. Using the ThOD corresponding to NH4+would lead to higher degradation rates. In both case, degradation of Aniline exceeds 40% after 7 days and 65 % after 14 days: the activity of the inoculum is thus verified and the test is considered as valid.

 

COMMENTS AND CONCLUSIONS

STEMONE undergoes almost no (1%) biodegradation after 28 days in the test conditions.

Thus, STEMONE should be regarded as not readily biodegradable according to this test.

The curves obtained with Aniline alone and with STEMONE+Aniline show no significant toxic effect of STEMONE on the microorganisms at the test concentration.

Validity criteria fulfilled:

not applicable

Conclusions:

The toxicity of STEMONE to microorganisms was assessed in an inhibition control of a standardised ready test performed according to OECD 301F. The curves obtained with Aniline alone and with STEMONE+Aniline show no significant toxic effect of STEMONE on the microorganisms at the test concentration of 100mg/L. This concentration can be considered the NOEC for the toxicity to STP microorganisms.

Executive summary:

The method used is basically the one described under No. 301 F in the OECD Guidelines for Testing of Chemicals. A measured volume of inoculated mineral medium, containing a known concentration of test substance (100 mg/l) as the nominal sole source of organic carbon, is stirred in a closed flask at a constant temperature (± 1°C) for up to 28 days. The consumption of oxygen is determined by measuring the quantity of oxygen (produced electrolytically) required to maintain constant the gas volume in the respirometer flask. Evolved carbon dioxide is absorbed in soda lime pellets. The amount of oxygen taken up by the microbial population during biodegradation of the test chemical (corrected for uptake by blank inoculum, run in parallel) is expressed as a percentage of ThOD (Theoretical Oxygen Demand, calculated from the elemental composition, assuming that carbon is oxidized to carbon dioxide and hydrogen to water) .

STEMONE undergoes almost no (1%) biodegradation after 28 days in the test conditions.

Thus, STEMONE should be regarded as not readily biodegradable according to this test.

The curves obtained with Aniline alone and with STEMONE+Aniline show no significant toxic effect of STEMONE on the microorganisms at the test concentration of 100 mg/L

Description of key information

In a standardised ready biodegradability screening study (Rudio 1996), no toxicity was observed in an inhibition control at a test concentration of 100 mg/L. This concentration can be considered as a NOEC for the toxicity to STP microorganisms.

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

Additional information

In the Biodegradation study, the curves obtained with Aniline alone and with STEMONE+Aniline show no significant toxic effect of STEMONE on the microorganisms at the test concentration of 100mg/L.