Benzyltriphenylphosphonium chloride

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:

From September 7th, 2017 to December 4th, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

Medium was prepared before the Study Plan was officially signed by the Study Director. This has no impact on the validity or integrity of the study.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Analytical purity: >=99.5%
- Purity test date: 02 March 2017
- Lot/batch No.: 180739
- Expiration date of the lot/batch: Not specified
- Appearance: Off-white powder
- Storage: At room temperature

Oxygen conditions:

aerobic

Inoculum or test system:

other: secondary effluent from a municipal sewage treatment plan receiving predominantly domestic sewage

Details on inoculum:

- Source: Waterschap Aa en Maas, 's-Hertogenbosch, The Netherlands
- Treatment: filtered through a coarse filter paper (irst 200 mL discarded) and kept aerated until inoculation.
- Inoculation: 4 mL filtrate of secondary effluent per litre of final volume

Duration of test (contact time):

28 d

Initial conc.:

1 mg/L

Based on:

test mat.

Remarks:

no correction was made for the purity/composition of the test item

Initial conc.:

3 mg/L

Based on:

test mat.

Remarks:

no correction was made for the purity/composition of the test item

Parameter followed for biodegradation estimation:

O2 consumption

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Remarks on result:

other: test item

Remarks:

1 mg/L

Key result

Parameter:

% degradation (O2 consumption)

Value:

1

Sampling time:

28 d

Remarks on result:

other: test item

Remarks:

3 mg/L

Results with reference substance:

In the procedure control, sodium acetate was degraded by at least 60% (72%) within 14 days (79% and 72% on day 7 and 14 respectively).

Theoretical Oxygen Demand

The ThOD of benzyltriphenylphosphonium chloride (test item) was calculated to be 2.59 mg O2 per mg.

The ThOD of sodium acetate (reference item) was calculated to be 0.78 mg O2/mg.

Biodegradation

The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed no biologically relevant biodegradation of benzyltriphenylphosphonium chloride at both concentrations. In the toxicity control less than 25% biodegradation occurred within 14 days (29% and 21% on day 7 and 14 respectively, based on ThOD). However, in the toxicity control the contribution of the ThOD of the reference and test item differs significantly (1.56 mg O2/L for the reference item versus 2.59 mg O2/L for the test item). Therefore, evaluation of the toxicity control based on ThOD is not the most appropriate method, as the ThOD is overestimated due to the higher ThOD of the test item. Results on day 14 showed that in the toxicity control an oxygen depletion of 0.84 mg O2/L was observed, compared to 1.12 mg O2/L for the reference item, while there was no oxygen depletion observed for the test item. This means the reference item was degraded >50% in the toxicity control and that sufficient microbial activity was present for biodegradation, i.e. no inhibitory effects.

Test Conditions

The pH at the start of the test was 7.4 in all vessels. The temperature recorded in a vessel with water in the same room varied between 22 and 23°C.

Acceptability of the Test

1. Oxygen depletion in the inoculum blank was less than 1.5 mg O2/L after 28 days (0.27 mg O2/L).

2. The residual concentration of oxygen in the test bottles was > 0.5 mg/L at any time.

3. All differences of duplicate biodegradation values expressed as mg O2/L were less than 20% (1-10%).

4. In the procedure control, sodium acetate was degraded by at least 60% (72%) within 14 days (79% and 72% on day 7 and 14 respectively).

Since all criteria for acceptability of the test were met, this study was considered to be valid.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item was not readily biodegradable under the conditions of the closed bottle test performed.

Executive summary:

The aerobic biodegradability of the test item was investigated in a GLP-compliant ready biodegradability study performed in accordance with OECD Guideline No. 301 D. The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed no biologically relevant biodegradation of the test item. The reference item was degraded >50% in the toxicity control (no inhibitory effects). The test item was not readily biodegradable under the conditions of the closed bottle test performed.

Description of key information

The aerobic biodegradability of the test item was investigated in a GLP-compliant ready biodegradability study performed in accordance with OECD Guideline No. 301 D. The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed no biologically relevant biodegradation of the test item. The reference item was degraded >50% in the toxicity control (no inhibitory effects). The test item was not readily biodegradable under the conditions of the closed bottle test performed.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

The aerobic biodegradability of the test item was investigated in a GLP-compliant ready biodegradability study performed in accordance with standard methods, without deviations. The study is considered as reliable (Klimisch 1) and is selected as a key study for the endpoint.