Potassium 1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulphonate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20 Jan - 20 Feb2003

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

EU Method C.4-B (Determination of the "Ready" Biodegradability - Modified OECD Screening Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Batch No.of test material: K100
- Sample no./year: 1069024/2002
- Purity test date: 10 Oct 2002
- Purity: 98.7%
- Expiration date of the lot/batch: August 12, 2004

Oxygen conditions:

aerobic

Inoculum or test system:

other: Secondary effluent of a treatment plant receiving predominantly domestic sewage

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Secondary effluent of a domestic sewage treatment plant (Wupper area water authority) treatment plant.
- Storage length: ca. 3 days based on collection date, test interval, and duration
- Pretreatment: separation of coarse particles by filtration

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Parameter followed for biodegradation estimation:

TOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium (per test guideline)
- Additional substrate: No
- Solubilising agent: None
- Test temperature: 22 ± 2 °C
- Inoculum concentration: 0.5mL/L
- Continuous darkness: yes

SAMPLING
- Sampling frequency: Initial time, Days 7, 14, 21, 27 and 28.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Duplicate
- Procedural control: Duplicate

Reference substance:

benzoic acid, sodium salt

Remarks:

20 mg DOC/L

Key result

Parameter:

% degradation (DOC removal)

Value:

14

Sampling time:

28 d

Table 1, DOC measurements during the biodegradation test

Condition	Replicate	Measurement	DOC (mg/L), Day 0	Day 7	Day 14	Day 21	Day 27	Day 28
Test item plus inoculum	A	1	22.0	22.0	20.0	20.0	19.0	19.0
		2	23.0	22.0	21.0	21.0	20.0	20.0
		mean	22.5	22.0	20.5	20.5	19.5	19.5
	B	1	22.0	22.0	30.0	19.0	19.0	19.0
		2	22.0	23.0	21.0	20.0	20.0	20.0
		mean	22.0	22.5	25.5	19.5	19.5	19.5
Blank inoculum	A	1	3.0	2.0	1.0	2.0	2.0	3.0
		2	3.0	2.0	1.0	2.0	2.0	3.0
		mean	3.0	2.0	1.0	2.0	2.0	3.0
	B	1	3.0	2.0	1.0	2.0	2.0	3.0
		2	3.0	2.0	1.0	2.0	2.0	3.0
		mean	3.0	2.0	1.0	2.0	2.0	3.0
	mean of blanks		3.0	2.0	1.0	2.0	2.0	3.0
Reference substance plus inoculum	A	1	23.0	3.0	3.0	3.0	3.0	3.0
		2	23.0	3.0	3.0	3.0	3.0	3.0
		mean	23.0	3.0	3.0	3.0	3.0	3.0
	B	1	23.0	3.0	3.0	3.0	3.0	2.0
		2	24.0	3.0	3.0	3.0	3.0	3.0
		mean	23.5	3.0	3.0	3.0	3.0	2.5

Table 2, percent biodegradation

Condition	Replicate	% biodeg, Day 0	Day 7	Day 14	Day 21	Day 27	Day 28
Test item plus inoculum	A	0	0	0	5	10	15
	B	0	0	0	8	8	13
	mean	0	0	0	7	9	14
Reference substance plus inoculum	A	0	95	90	95	95	100
	B	0	95	90	95	95	100
	mean	0	95	90	95	95	100

Validity criteria fulfilled:

yes

Remarks:

difference of replicate values <20% (2%), reference substance at pass level by day 14 (day 7)

Interpretation of results:

not readily biodegradable

Conclusions:

PFBS K-salt is not readily biodegradable (14% DOC removal, EU method C.4-B)

Executive summary:

Ready biodegradability of PFBSK+ was assessed according to EU method C.4-B (modified OECD screening method, equivalent to OECD guideline 301E). Sodium benzoate was used as reference.  PFBSK+ degraded 14% during the test period.  PFBSK+ is not readily biodegradable.

The study was conducted in accord with internationally accepted guidelines under GLP criteria.  Details are lacking about the conduct of the study, in particular regarding the inoculum, however the validity criteria were met. The study is considered reliable with restriction and is suitable for use in Risk Assessment, Classification & Labelling, and PBT Analysis.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2008

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

Stated results contradicted by Figure

Justification for type of information:

Study is of the free acid form of PFBS. In buffered solution, biodegradation testing on the acid is equivalent to testing on the potassium salt.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Automated test using OxiTop

Deviations:

not specified

GLP compliance:

no

Specific details on test material used for the study:

PFBS standard (98%) was obtained from Sigma–Aldrich (Germany)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Aeration tank of a sewage treatment plant in Darmstadt, Germany
- Preparation of inoculum for exposure: aeration in a secondary effluent for 7 days at the test temperature. Coarse particles were removed by filtration

Duration of test (contact time):

40 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: As per OECD 301
- Additional substrate: No
- Solubilising agent: None
- Test temperature: 20 ± 0.2 °C
- Suspended solids concentration: 10 mL sludge suspension/L

TEST SYSTEM
- Culturing apparatus: 164-mL glass bottles containing a magnetic stir-bar and filled to top with mineral medium. Bottles were closed with rubber sleeve holding NaOH pellets to absorb evolved CO2, and capped with WTW OxiTop measuring devices to record pressure. Bottles were stirred in an incubation cabinet during the experiment.
- Number of culture flasks/concentration: Duplicate

SAMPLING
- Sampling frequency: Daily
- Sampling method: Automated data logging

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

< 1

Sampling time:

28 d

Remarks on result:

other: PFBS was observed to biodegrade <1% of the total biodegradation within the experimental duration of 40 days.

Parameter:

% degradation (O2 consumption)

Value:

< 1

Sampling time:

40 d

Details on results:

The test was conducted on several fluorochemical surfactants as well as PFBS. The figure shows roughly equivalent %ThOD for one surfactant (Zonyl) and PFBS. Nevertheless the report states a biodegradation of 13% for the surfactant and <1% for PFBS. Both values are contradicted by the depicted biodegradation curve, in which both materials have %ThOD values in the range 5-10%. In addition, the stated % ThOD for the reference substance, 70.4%, is not supported by the biodegradation curve. It is possible that the biodegradation curve shows results for a single run whereas numeric results are means of several runs. The conclusion that PFBS shows little biodegradation is not questioned, but the value is not known with certainty.

Validity criteria fulfilled:

not specified

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

PFBS was biodegraded <1% in an automated test conducted according to OECD 301F. Results for the free acid are directly applicable to PFBSK+.

Executive summary:

PFBS biodegradation was examined in an automated test conducted according to OECD 301F. Several fluorinated surfactants were examined in the same study. Sodium acetate was used as reference substance, and the test duration was extended to 40 days. PFBS was biodegraded <1% over the test interval. PFBS is not readily biodegradable. In buffered media, biodegradation testing on the free acid is equivalent to testing on the salt. Therefore, results for PFBS are directly applicable to PFBSK+.

The test was conducted according to internationally accepted guideline using an automated test system. However, limited details are available on the study method, and the depicted biodegradation-time curve contradicts numeric results. The central conclusion of lack of biodegradation is not disputed, but the numeric result is not considered reliable.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2008

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Justification for type of information:

Study is of the free acid form of PFBS. In buffered solution, biodegradation testing on the acid is equivalent to testing on the potassium salt.

Qualifier:

according to guideline

Guideline:

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

Deviations:

not specified

GLP compliance:

not specified

Specific details on test material used for the study:

PFBS standard (98%) was obtained from Sigma–Aldrich (Germany)

Oxygen conditions:

aerobic

Inoculum or test system:

natural water: freshwater

Remarks:

Rhine River water

Details on inoculum:

- Source of inoculum: taken at Rhine km 463.6 (Biebesheim, Germany) in spring 2008

Duration of test (contact time):

28 d

Initial conc.:

73 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: As per OECD 301
- Additional substrate: No
- Solubilising agent: None
- Test temperature: 20 ± 1 °C
- Continuous darkness: yes
- Number of culture flasks/concentration: Duplicate
- Inoculum blank: Yes
- Sampling frequency: Weekly

Reference substance:

acetic acid, sodium salt

Preliminary study:

Total organic carbon (TOC) was measured using EPA Method 415.1. The value was 0.15 mg C/mg sample. Calculated ThOD was 0.45 mg O2/mg sample

Key result

Parameter:

% degradation (O2 consumption)

Value:

< 3

Sampling time:

28 d

Details on results:

The test was conducted on several fluorochemical surfactants as well as PFBS. The degree of biodegradation was deemed not significant by study authors, with a value <3% reported. No statistics were provided or described.

Results with reference substance:

While the paper indicates that sodium acetate was used as a reference substance, no results are provided. One of the fluorinated substances attained 80% degradation within 28-days, indicating a viable inoculum.

Validity criteria fulfilled:

not specified

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

PFBS was not biodegraded in a closed bottle test (OECD 301D) conducted with a Rhine River inoculum. Results for the free acid are directly applicable to PFBSK+.

Executive summary:

PFBS biodegradation was examined in an closed bottle test conducted according to OECD 301D. Several fluorinated surfactants were examined in the same study. Sodium acetate was used as reference substance. PFBS was biodegraded <3% over the test interval. PFBS is not readily biodegradable. In buffered media, biodegradation testing on the free acid is equivalent to testing on the salt. Therefore, results for PFBS are directly applicable to PFBSK+.

The test was conducted according to an internationally accepted guideline. However, limited details are available on the study method, and the study was not done under GLP criteria. Therefore, the study is deemed reliable with restrictions and is suitable as supporting information for Risk Assessment, Classification & Labeling, and PBT Analysis.

Description of key information

PFBSK+ is not readily biodegradable.

Additional information

Ready biodegradability of PFBSK+ was examined under three test guidelines. The key study was done under EU method C.4-B (modified OECD screening method, equivalent to OECD guideline 301E) and showed 14% biodegradation during the test period. The study was GLP-compliant and is considered reliable with restrictions. The other two studies were done on the free acid (PFBS) rather than the potassium salt. However, because the test materials were tested in standard mineral medium buffered to pH ca. 7.4, testing on the free acid is equivalent to testing on the potassium salt. Both supporting studies were published in a scientific journal are not GLP-compliant and are considered reliable with restrictions. PFBS was not biodegraded (<3%) in a closed bottle test (OECD 301D) conducted using a Rhine River inoculum. Also, PFBS was not biodegraded in an automated test conducted according to OECD 301F, although the depicted biodegradation-time curve contradicts the reported numeric results. The central conclusion of lack of biodegradation is not disputed for the 301F study, but its numeric result is not considered reliable.