tert-pentylbenzene

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:

other: GLP Guideline Study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

no

Principles of method if other than guideline:

One minor deviation from OECD Guideline 301 D is that ammonium chloride is omitted from the medium to prevent nitrification.

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: RWZI Horstermeer, Nederhorst den Berg, the Netherlands. This is an activated sludge plant treating
predominantly (>85%) domestic waste water.
- Pretreatment: The sludge was preconditioned to reduce the endogenous respiration rate. The diluted sludge (50 mg dry weight/litre) was aerated for a period of one week.
- Concentration of sludge: the sludge was diluted to a concentration of 2 mg dry weight/l in the test bottles.
- Water filtered: no.

Duration of test (contact time):

28 d

Initial conc.:

8.5 mg/L

Based on:

act. ingr.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral salt solution prepared in distilled water.
- Solubilising agent (type and concentration if used): Not applicable.
- Test temperature: 20°C.
- pH: 7.0 (mineral salt solution), 7.1 (test solution)
- pH adjusted: no
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparaturs: 280 ml BOD bottles
- Number of culture flasks/concentration: 10 bottles per treatment.

SAMPLING
- Sampling frequency: on Day 0, 7, 14, 21 and 58.
- Sampling method: the oxygen content was measured in the bottle.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes

Reference substance:

acetic acid, sodium salt

Preliminary study:

Not applicable.

Parameter:

% degradation (O2 consumption)

Value:

3.9

Sampling time:

28 d

Details on results:

Tertiary-amylbenzene was not toxic to the micro-organisms, because sodium acetate was degraded in the presence of tertiary-amylbenzene for
more than 25%.

Results with reference substance:

The biodegradation of sodium acetate in the control series (group C) was used as a parameter for microbial activity of the inoculum. Within 14 days
86% of the sodium acetate was degraded. Therefore it can be concluded that the microbial activity of the inoculum was sufficient.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Under the test conditions of this study, tertiary-amylbenzene is not considered as readily biodegradable.

Executive summary:

The biodegradability of Tertiary-amylbenzene was determined following OECD guideline 301 D and according to GLP.

Tertiary-amylbenzene was added to an aqueous mineral salt medium and exposed to relatively low numbers of unadapted micro-organisms under aerobic conditions for a period of 28 days. The test compound was the only source of carbon and energy which was available to micro-organisms. To follow the biodegradation of tertiary-amylbenzene, the oxygen consumption by the micro-organisms was determined.

The reference compound sodium acetate was degraded for > 60% (86%) within 14 days. Therefore it can be concluded that the microbial activity of the inoculum was sufficient.

Sodium acetate was also degraded in the presence of tertiary-amylbenzene during the test period. This indicates that tertiary-amylbenzene is not toxic to the micro-organisms at the tested concentration of 2.0 mg/L.

Tertiary-amylbenzene was not sifnificantly degraded (<= 16% during the course of the study), therefore, the test substance is not considered as readily biodegradable according to EU criteria.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater