Distillates (Fischer-Tropsch), C8-26-branched and linear

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

This endpoint has been reviewed, assessed and accepted by UK-HSE as competent authority for the notification of a new substance [EC number 481-740-5; Data from UK-Notification Dossier by Shell U.K. Limited in accordance with Directive 92/32/EEC (Articles 7/8/9/12) O.J.L 154, Volume 35, 5 June 1992; Notification Report 06-31-0127-00 from 1st Nov, 2006]. Restriction: non-GLP, but in accordance with OECD 301F, validity criteria fulfilled.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Distillates (Fischer-Tropsch), C8-26, branched and linear

Cas Number:

848301-67-7

Molecular formula:

main general molecular formula: CnH(2n+2)

IUPAC Name:

Distillates (Fischer-Tropsch), C8-26, branched and linear

Details on test material:

- Name of test material (as cited in study report): SMDS gas oil [Shell Middle Distillate Synthesis] from Fisher-Tropsch synthesis
- Lot/batch No.: SMDS 1 (SPL 5757/94) and SMDS 2 (SPL 34112/00)

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

The sludge used as inoculum was collected from a sewage treatment plant (Welch Water, Sealand Road, Chester)
In order to reduce background oxygen consumption, the activated sludge was washed and and then aerated with moist air for 24 hours
at the test temperature prior to use. The sludge was used at a final concentration of 30 mg/dry solids/litres.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

30 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

75

Sampling time:

28 d

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

58 - 60

Sampling time:

10 d

Remarks on result:

other: "pass" criterion for ready biodegradability: >60% degradation within 10 days

Details on results:

Results from study of the biodegradability of samples of Distillates, (Fischer-Tropsch), C8-26 - branched and linear have been reported by
Battersby and Bumpus (2001). They reported that 74-75% degradation (measured as percentage of the theoretical oxygen demand) of two Shell
Middle Distillate Synthesis (SMDS) samples was achieved in 28 days using a method consistent with OECD Guideline 301 F (manometric respirometer). One sample just met the stringent 10-day window-criterion, and the second just failed to meet it. Albertus and Phillips (2005) have reported similar
results (>75% degradation in 28 days) from a test carried out in accordance with the same guideline on a sample of SASOL SPD Diesel. The study
result met the 10-day window criterion.
Predicted biodegradability: The biodegradability of the chemical components of Distillates, (Fischer-Tropsch), C8-26 - branched and linear has also
been predicted in accordance with the methods described by Peter Fisk Associates (2006). The results of applying these methods to a typical
composition show that 30% of its mass would be considered readily biodegradable passing the 10-day window (RB10), 68% would be readily
biodegradable not passing the 10-day window (RBN) and 2% would be inherently biodegradable (INH). No fraction would be inherently biodegradable, not meeting the criteria (INHN).

BOD5 / COD results

Results with reference substance:

benzoic acid salt: biodegradation > 80% within 10 days

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

In OECD 301F the pass level for "ready biodegradability" is >= 60% ThOD und must be reached 10 days after biodegradation has first passed the 10%ThOD (10 day window). This is a stringent "pass" criterion and its applicability to poorly soluble substances has been criticised. The test substance has shown 58-60% biodegradability within the 10 day window, so the criterion was almost fulfilled. The test substance SMDS Diesel is considered readily biodegradable.
Biodegradability conclusion: A reasonable conclusion that can be drawn is that, Distillates (Fischer-Tropsch), C8-26 - branched and linear should also be considered to be readily biodegradable. The test data also support the view that the substance passes the 10-day window criterion for ready biodegradability.