Pent-1-ene

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

Study period:

01 June 2017 to 31 July October 2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)

GLP compliance:

not specified

Specific details on test material used for the study:

EAG test substance NO. 13777

Inoculum or test system:

activated sludge (adaptation not specified)

Duration of test (contact time):

21 d

Initial conc.:

17 mg/L

Based on:

other: C

Parameter followed for biodegradation estimation:

inorg. C analysis

Details on study design:

1. Test vessels: 160 mL glass serum bottles filled with 107 mL test medium containing 4 mg/L inoculum.
2. Test substance dosing: Preliminary work showed that pentene-1 is miscible with silicone oil AR20 and not from the solution in a closed container. For ready biodegradability test, pentene-1 was mixed with silicone oil AR 20 (2) as the dosing stock solution. Specifically, 1.8303 g silicone oil was mixed with 60 µL pentene 1 in a 2.0 mL HPLC glass vial and the vial was immediately capped. Then 100 µL of the mixed stock was dosed to each serum bottle to give a final concentration of ~17 mg C/L. The sample bottles were immediately crimp-sealed and the solution was rigorously mixed by hand shaking.
3. Reference dosing: A 3.5 µL aliquot of pure 1-octanol was directly added to each serum bottle to give a final concentration of ~20 mg C/L. The bottles were immediately crimp-sealed and the solution was rigorously mixed by hand shaking.
4. Control: A 100 µL aliquot of pure silicone oil AR20 was directly added to each serum bottle to serve as the background control. The bottles were immediately crimp-sealed and the solution was rigorously mixed by hand shaking.
5. Incubation: The sample bottles were laid horizontally and placed on a platform shaker with constant oscillation at ~ 120 rpm.
6. Sampling: On Days 7, 15, and 21, sample bottles were injected with 1 mL of 7 N NaOH, respectively and were further processed for IC analysis.

Reference substance:

other: 1-octanol

Key result

Parameter:

% degradation (O2 consumption)

Value:

0.6

Sampling time:

21 d

Details on results:

No biodegradation was observed for pentene-1 under the test conditions. This is likely due to that petene-1 was not bioavailable for microbes presented in activated sludge inoculum. Pentene-1 is extremely volatile and water insoluble, it could migrate to the headspace of the sample bottles even under constant agitation of the test medium.

Results with reference substance:

For reference material, more than 70% of 1-octanol was degraded in 15 days, indicating that the test system was biologically viable.

Validity criteria fulfilled:

not applicable

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Under the test conditions in accordance with OECD 310 guideline and using silicone oil AR 20 to facilitate dispersion of the test material, pentene-1 still was not biodegraded in test medium containing activated sludge inoculum.

Executive summary:

The feasibility of testing pentene-1 in sealed vessels (headspace test) following OECD 310 study guideline was studied in a preliminary work. For reference material, more than 70% of 1-octanol was degraded in 15 days, indicating that the test system was biologically viable. No biodegradation was observed for pentene-1 under the test conditions. This is likely due to that pentene-1 was not bioavailable for microbes presented in activated sludge inoculum. Pentene-1 is extremely volatile, it could migrate to the headspace of the sample bottles even under constant agitation of the test medium.

Under the test conditions in accordance with OECD 310 guideline and using silicone oil AR 20 to facilitate dispersion of the test material, pentene-1 still was not biodegraded in test medium containing activated sludge inoculum.

As no biodegradation of pent-1 -ene was observed in this preliminary work, no further study was performed. This study is therefore considered valid with restrictions despite the fact that it was not carried out under GLP after REACH came into force. The substance is considered as not readily biodegradable.

Description of key information

Study similar to OECD 310, non-GLP, key study, validity 2:

0.6% of biodegradation after 21 days (inoculum: activated sludge)

Under test conditions, the percentage biodegradation of the test item did not reach 60% in 10 day-window, so the substance can not be considered as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

One valid key study is available (EAG, 2017) to assess the readily biodegradation of the registered substance as a preliminary test.This study was performed to determine any potential for biodegradability of the test item using a method designed for highly volatile substances: the sealed vessels (headspace test) following OECD 310 study guideline.

For reference material, more than 70% of 1-octanol was degraded in 15 days, indicating that the test system was biologically viable. No biodegradation was observed for pentene-1 under the test conditions. This is likely due to that pentene-1 was not bioavailable for microbes presented in activated sludge inoculum. Pentene-1 is extremely volatile, it could migrate to the headspace of the sample bottles even under constant agitation of the test medium.

Under the test conditions in accordance with OECD 310 guideline and using silicone oil AR 20 to facilitate dispersion of the test material, pentene-1 still was not biodegraded in test medium containing activated sludge inoculum.

As no biodegradation of pent-1 -ene was observed throughout this preliminary work, it was not considered useful to perform a definitive study under GLP as no degradation would be expected. This study is therefore considered valid with restrictions despite the fact that it was not carried out under GLP after REACH came into force. The substance is considered as not readily biodegradable.