5-bromo-1,3-dichloro-2-fluorobenzene

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

SEPA, P.R. China, the Guidelines of Chemical Testing Good Laboratory Practices (HJ/T 155-2004), China is not a member of OECD and hence there is no agreement on mutual acceptance of data

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

SEPA, P.R. China, the Guidelines of Chemical Testing Good Laboratory Practices (HJ/T 155-2004), China is not a member of OECD and hence there is no agreement on mutual acceptance of data

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

Activated sludge was collected from at least ten sites recommended by MEP of P.R. China Guidelines for the Testing of Chemicals and the OECD Guidelines for the Testing of Chemicals. Activated sludge is suggested to be derived from the areas where a variety of chemicals are used and discharged. The sources of inoculums used in this study included sewage treatment works, rivers, lakes, etc.

Duration of test (contact time):

28 d

Initial conc.:

30.44 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

TEST CONDITIONS
- Composition of medium:
- Additional substrate: a mineral medium was prepared by making up 3 mL each of stock solutions A, B, C, D to 1000 mL with deionised water, with stock solution A consisting of 0.8503 g potassium acid phosphate, 2.175 g of dipotassium hydrogen phosphate, 4.4607 g dibasic sodium phosphate dodecahydrate and 0.17 g ammonium chloride dissolved in deionised water and made up to 100 mL, stock solution B consisting of 2.25 g of magnesium sulfate heptahydrate dissolved in deionised water and made up to 100 mL, stock solution C consisting of 2.7501 g calcium chloride dissolved in deionised water and made up to 100 mL and stock solution D consisting of 0.025 g iron (III) chloride hexahydrate dissolved in deionised water and made up to 100 mL
- Test temperature: 25 ± 2 °C
- pH: 6.37 to 6.91 in inoculum controls, 6.5 to 6.57 in test suspensions, 8.4 to 8.93 in abiotic controls
- pH adjusted: pH in stock solution A of the mineral medium was adjusted with HCl from 7.63 to 7.39
- Aeration of dilution water: no
- Suspended solids concentration: 100 mg/L for test substance, 30 mg/L for reference substance sodium benzoate
- Continuous darkness: yes
- Other:

TEST SYSTEM
- Culturing apparatus: fill and draw activated sludge vessels
- Number of culture flasks/concentration: three
- Method used to create aerobic conditions: aeration of activated sludge until use
- Measuring equipment: automated respirometer
- Test performed in closed vessels due to significant volatility of test substance: yes
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: a pre-treated foam stopper was added on top of the CO2 trap cuvette to potentially trap the volatile test substance in the abiotic control and abiotic control with sterilised sludge

SAMPLING
- Sampling frequency: samples of the test vessels containing test substance, abiotic control and abiotic control with sterilised sludge were taken at the end of the 28-day incubation period
- Sampling method: not specified
- Sterility check if applicable: yes
- Sample storage before analysis: not applicable

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

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (TOC removal)

Value:

0

Sampling time:

28 d

Validity criteria fulfilled:

yes

Interpretation of results:

not inherently biodegradable

Conclusions:

The substance was found to be not inherently biodegradable.

Executive summary:

The inherent biodegradability of the test substance was studied in accordance with OECD TG 302C under Chinese GLP. The test was performed in parallel in three vessels containing about 30.4 mg/L of test substance, and 100 mg of aerated activated sewage sludge collected from ten sites in China. Sewage sludge was suspended in aerated mineral medium and fed with artificial sewage before being used in the study. The test was carried out in a closed system in the dark over a period of 28 days at a temperature of 25 ± 2 °C. A parallel study with the reference substance sodium benzoate was conducted under the same conditions, however the test concentration of sodium benzoate was 96.3 mg/L and the concentration of sludge was 30 mg/L. The oxygen consumption was measured daily using and automatic respirometer. Basel on the oxygen consumption, no degradation (0%) was observed after the incubation period of 28 days. The HPLC analysis of the residual concentration of the test substance in the test vessels showed that a large fraction was lost from the test vessels (with residual concentrations ranging from 10.1 to 17.8% of initial concentrations), presumably due to evaporation of the volatile test substance. The total residual concentration of test substance in the abiotic control vessels at the end of the 28-day incubation period was 11.6%, which is above the required threshold of 10%. This again indicates that most of the test substance was lost from the test vessel due to volatilisation. However, the pre-treated foam stoppers used in the abiotic control vessels only captured a very small amount of the test substance. The test with the reference substance resulted in 76.4% degradation after 7 and 86.4% degradation after 14 days, demonstrating the suitability of the test system and activated sewage sludge.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018-09-04 until 2018-10-02

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study conducted in accordance with current guidelines and GLP compliance

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

(1992)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Council Regulation (EC) No 440/2008 Version /

Version / remarks:

May 2008

Deviations:

no

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 (e.g. location, sampling depth, contamination history, procedure): sewage treatment plant Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany
- Date of sampling: 04th September 2018
- Storage conditions: No storage
- Preparation of inoculum for exposure: No washing, the concentration was adjusted to 3.8 g/L and verified by dry mass measurement.
- Pretreatment: Kept aerobic until use
- Concentration of sludge in the test: 29.6 mg dry mass/litre

Duration of test (contact time):

28 d

Initial conc.:

68 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

(53.4 mg ThOD)

Details on study design:

- The concentration in the test assays were 68 mg per litre mineral test medium (17 mg/250 mL). This amount (68 mg) test item correspond to 53.4 mg theoretical oxygen demand (ThOD). No emulsifiers or solvents were used. The required amount to ensure a final concentration of 68 mg/L (17 mg per 250 mL) was added directly on a weight basis via Teflon discs. Subsequently, the mineral medium was added to the vessels.
- The concentration in the test vessels with reference item (procedural control, toxicity control) was 100 mg per liter mineral test medium (25 mg/250 mL).
- A further solution containing both test and reference item at the same concentrations as in the ind
ividual solutions (test item 48 mg/L, reference item 100 mg/L) was prepared to determine the possible toxicity of the test item against the inoculum.
- Further flasks with mineral medium only were prepared for inoculum controls.
- Abiotic controls were also prepared to measure any possible abiotic degradation; a solution of the test item at about 68 mg/L was sterilized by the addition of 10 mL/L NaN3 (100 g/L).
- In all test assays except of the abiotic controls, 1.96 mL of the inoculum stock solution were transferred for inoculation (per 250 mL) resulting in a concentration of 29.6 mg dry mass/litre (7.4 mg dry mass/250 mL).

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

St. dev.:

0

Sampling time:

28 d

Details on results:

The average percent biodegradation of the test item in the test media was found to be below 0% since less oxygen was consumed in the test media than in the blank inoculum. No biodegradation within the 10-day-window could be calculated. Even when the start criterium of the 10-day-window (10 % degradation rate) was reached within the 28 days of incubation, the mean degradation rate at the end of the window was below 10 %.

The reference item was degraded by an average of 86% by Exposure Day 14, thus confirming suitability of the activated sludge. At the end of the test (Day 28), the reference item was degraded by an average of 90%.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test item was not readily biodegradable under the conditions of the test. This study is considered to be relevant, reliable, adequate for risk assessment, and adequate for classification purposes.

Executive summary:

The ready biodegradability of the test item was investigated according to the manometric respirometry test design and carried out according to the OECD guideline for Testing of Chemicals No. 301 F (1992), EPA OPPTS 835.3110 and the Council Regulation (EC) No 440/2008 of 30 May 2008. The ready biodegradability of the test item was investigated at a concentration of 68 mg/L in a manometric respirometry test using domestic aerobic activated sewage sludge incubated at 22°C in the dark over 28 days under continuous stirring. The biochemical oxygen demand (BOD) was measured daily and the percentage degradation was calculated from the theoretical oxygen demand (ThOD) after correcting for the BOD of inoculum controls. The average percent biodegradation of the test item in the test mediawas found to be below 0% after 28 days of incubation, since less oxygen was consumed in the test media than in the blank inoculum. No biodegradation within the 10-day-window could be calculated. Even when the start criterium of the 10-day-window (10 % degradation rate) was reached within the 28 days of incubation, the mean degradation rate at the end of the window was below 10 %. Since the threshold value of 60% was not surpassed in a 10-day-window within the 28-d period, the test item was not ready biodegradable under the test conditions. The test item had no inhibitory effect on the activity of activated sludge microorganisms at the tested concentration. In the procedural controls, the reference substance sodium benzoate was degraded by an average of 86% by exposure day 14, and reached an average biodegradation of 90% by the end of the test (day 28), thus confirming suitability of the activated sludge.

Description of key information

Ready biodegradability: not biodegradable (GLP, OECD TG 301F)

Inherent biodegradability: not biodegradable (China GLP, OECD TG 302)

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

The substance was not biodegradable in the available studies on ready or inherent biodegradability. Significant volatilisation of the substance from the test vessels was observed during the studies, and this is anticipated to be the main process of removal from water under environmental conditions.