Hexan-4-olide

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, adapted

Details on inoculum:

Specification
Activated sludge from a biologic sewage treatment plant was used as inoculum. The cho-sen plant treats mostly domestic sewage.
Source and Pre-Treatment of inoculum
Source
The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf.
Date of collection: 12. Jan. 2018, batch no: 20180112.
Pre-Treatment
The sludge was filtrated, washed with test medium (2x) and re-suspended in test medium. It was then aerated until use. The dry matter was determined to contain 4900 mg of sus-pended solids/L.

Duration of test (contact time):

ca. 28 d

Initial conc.:

ca. 27.6 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Reference substance:

aniline

Remarks:

positive control

Test performance:

All validity parameters and values are presented in the following table:
Validity
Parameter Criterion Found Assessment
IC content of test item solution in medium ≤ 5% of TC 0 % valid
CO2 emitted by the controls < 70 mg/L 8.9 mg/L valid
Difference within replicates ≤ 20% 11.1 % valid
Degradation of positive control > 60% ≤ 14 days 9 days valid
Degradation in the toxicity flask on day 14 > 25% 83.7% non-toxic
Note: All calculations are performed with unrounded values. Therefore, re-calculation with rounded values may lead to slightly different results.

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 91

Sampling time:

29 d

Remarks on result:

other: The test item gamma-Dodecalactone is considered as “readily biodegradable“

Details on results:

The test item gamma-Dodecalactone is considered as “readily biodegradable“.
The degree of biodegradation reached 91 % after 28 days.
The 10-day-window began on day 2, at its end, 80 % degradation were reached (graphical evaluation), surpassing the pass level of 60 % given in the OECD guide-line.
The abiotic degradation reached 1.4 %.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item gamma-Dodecalactone is considered as “readily biodegradable“.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater