Hydrocarbons, C12-C15, n-alkanes, isoalkanes, cyclics, < 2% aromatics

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:

2013-10-16 to 2013-11-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted according to a standard guideline without deviations from the protocol, and was conducted under GLP guidelines.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

i) pH readings of the test item on day 28 was not taking due to the volatile and oily nature of test substance. (ii) Temperature of incubator for test item and control vessels at days 9, 10 and 11 exceed ±1°C (20-24°C).

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

yes

Remarks:

i) pH readings of the test item on day 28 was not taking due to the volatile and oily nature of test substance. (ii) Temperature of incubator for test item and control vessels at days 9, 10 and 11 exceed ±1°C (20-24°C).

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

yes

Remarks:

i) pH readings of the test item on day 28 was not taking due to the volatile and oily nature of test substance. (ii) Temperature of incubator for test item and control vessels at days 9, 10 and 11 exceed ±1°C (20-24°C).

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

A mixed population of sewage treatment micro-organisms was obtained on 11 October 2013 from the final effluent stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK. The site treats predominantly domestic sewage. Sample of the inoculum was filtered through a coarse filter paper (first approximate 200 ml discarded) and maintained on aeration in a temperature controlled room at 21±1°C before use.

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Reference substance:

aniline

Preliminary study:

Preliminary solubility/dispersibility study was performed in order to determine the most suitable method of preparation.

Test performance:

Deviations from study plan:
i) The pH readings of the test preparation on Day 28 was not taken due to the potentially volatile and oily nature of the test substance. It was therefore, not possible to determine whether the pH fell within the required range of 6.0 - 8.5. This deviation was considered to have no adverse effect on the integrity of the study given that >60% degradation was achieved.

ii) The incubator temperature where the test substance and toxicity control vessels were placed was observed to exceed the allowed temperature deviation of ±1°C (20-24°C) on Days 9, 10 and 11. The deviation was considered not to have any adverse effect on the outcome of the study because the temperatures were within the specification of the test guideline.

Parameter:

% degradation (O2 consumption)

Value:

13

Sampling time:

5 d

Parameter:

% degradation (O2 consumption)

Value:

34

Sampling time:

10 d

Parameter:

% degradation (O2 consumption)

Value:

50

Sampling time:

15 d

Parameter:

% degradation (O2 consumption)

Value:

60

Sampling time:

20 d

Parameter:

% degradation (O2 consumption)

Value:

71

Sampling time:

28 d

Details on results:

The test substance exhibited rapid biodegradation and assessed as readily biodegradable. By Day 28, the average percent biodegradation of the test substance was 71%. The test substance reached 13% biodegradation on approximately Day 5 and 50% biodegradation on approximately Day 15.

Biodegradation was based on oxygen consumption and the theoretical oxygen demand of the test substance was calculated using results of an elemental analysis of the test substance.

Results with reference substance:

The reference substance biodegraded to an extent of 79% at Day 28. At Day 14, 63% biodegradation was observed, at Day 20, the biodegradation was 77%.

Results:

Daily BOD values for the test substance, procedure control, toxicity control and inoculum control vessels are in Table 1. The percentage biodegradation values of the test and reference substance and toxicity controls are shown in Table 3 below. The pH results are in Table 2.

Table 3: Biodegradation values

Day	Procedure control	Test item			Toxicity control
		R1	R2	Mean
0	0	0	0	0	0
1	0	0	0	0	0
2	0	0	0	0	0
3	0	0	2	1	0
4	0	3	7	5	2
5	1	12	13	13	7
6	1	17	19	18	10
7	1	21	24	23	18
8	1	24	29	27	31
9	1	27	33	30	40
10	1	30	37	34	45
11	4	33	41	37	50
12	20	36	45	41	55
13	49	39	48	44	59
14	63	42	51	47	62
15	68	45	54	50	64
16	71	47	56	52	66
17	73	49	58	54	68
18	75	51	60	56	69
19	76	53	62	58	70
20	77	55	64	60	72
21	77	56	66	61	73
22	78	58	68	63	73
23	78	59	70	65	74
24	78	61	72	67	75
25	78	62	73	68	76
26	79	63	74	69	77
27	79	64	75	70	77
28	79	65	76	71	78

R₁, R₂= Replicates 1 and 2

Validation criteria:

The mean BOD of the inoculated mineral medium (control) was 33.72 mg O₂/L after 28 days and therefore satisfied the validation criterion of the test guideline.

The difference between extremes of replicate BOD values at the end of the test and at the end of the 10-day window was <20% and therefore satisfied the validation criterion of the test guideline.

Biodegradation:

The test item achieved 71% biodegradation after 28 days and is therefore considered readily biodegradable.

The toxicity control attained 62% biodegradation after 14 days and 78% biodegradation after 28 days, thereby confirming that the test item was not toxic to the sewage treatment micro-organisms used during the study.

Aniline (procedure control) attained 63% biodegradation after 14 days and 79% biodegradation after 28 days thereby confirming the suitability of the inoculum and test conditions.

Chemical analysis of the 100 mg/l test preparation at 0 hours, showed that a mean measured concentration of 97% of nominal was obtained. A decline in measured test concentration was observed at day 28 to 1% of nominal (96% loss over test duration).

The losses observed by chemical analysis were higher that those observed by oxygen consumption, this was considered to be due to possible losses of the test substance due to its volatility during sampling and analytical procedures.

Another factor in the apparent reduced biodegradation value based on oxygen consumption values compared to losses calculated from the chemical analysis conducted may be due to incorporation of the test substance or degradation products of the test substance into the microbial biomass. In such cases, the micro-organisms present utilise carbon originating from the test substance to increase their biomass by incorporating the carbon into new cells. This effectively removes the test substance from the aqueous phase and hence reduces the apparent biodegradation of the test item by oxygen consumption.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

A ready biodegradation value of 71% after 28 days was observed for the substance in accordance with OECD 301F and in compliance with GLP. The result is considered reliable.

Executive summary:

The test substance biodegraded to an extent of 71% after 28 days. The data support characterizing the test substance as readily biodegradable, not expected to persist in the environment under aerobic conditions. Although it did not meet the 10 -day window requirement, it is characterized as readily biodegradable because the criterium is not applied to multi-component substances when assessing their ready biodegradability.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

August to September 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to a standard guideline without deviations from the protocol and was conducted under GLP guidelines.

Justification for type of information:

A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

An un-acclimated activated sludge inoculum was used in this study. The inoculum was obtained from the Somerset Raritan Valley Sewage Authority, Bridgewater, New Jersey, USA. The treatment plant receives predominantly domestic sewage. The sewage sample was obtained one day prior to test initiation. The microbial count was 106 CFU/mL. The sludge supernatant was added at a 1% loading volume of to test medium. Test medium consisted of glass distilled water and mineral salts (phosphate buffer, ferric chloride, magnesium sulfate, calcium chloride). One liter of test medium and activated sludge, which was aerated for 24 hours with carbon dioxide free air, was added to each one liter respirometer flask.

Duration of test (contact time):

28 d

Initial conc.:

ca. 38 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Triplicate test systems were used to evaluate the biodegradability of the test substance and the positive control substance at mean concentrations of approximately 38 mg/L and 50 mg/L, respectively. Blank test systems, which did not contain the test or positive control substance, were run concurrently in triplicate. The test substance was weighed in an air tight syringe and injected into the test medium. The test system was sealed immediately after addition of the test substance. An aliquot of the positive control stock solution was added to the appropriate test flasks. All test vessels were stirred constantly using magnetic stir bars and plates. The study was conducted at a temperature of 21°C.

Reference substance:

benzoic acid, sodium salt

Preliminary study:

A preliminary study was not conducted.

Test performance:

No deviations from the protocol occurred that affected the integrity of the study data.

Parameter:

% degradation (O2 consumption)

Value:

4.8

Sampling time:

2 d

Parameter:

% degradation (O2 consumption)

Value:

12.7

Sampling time:

3 d

Parameter:

% degradation (O2 consumption)

Value:

53

Sampling time:

12 d

Parameter:

% degradation (O2 consumption)

Value:

60.2

Sampling time:

18 d

Parameter:

% degradation (O2 consumption)

Value:

67.6

Sampling time:

28 d

Remarks on result:

other: Percent biodegradation was still increasing.

Details on results:

The test substance exhibited rapid biodegradation, and assessed as readily biodegradable. The half-life was approximately 12 days. By Day 31, the average percent biodegradation of the test substance was 68.7%. The test substance reached 10% biodegradation on approximately Day 3 and 60% biodegradation on approximately Day 18.

Biodegradation was based on oxygen consumption and the theoretical oxygen demand of the test substance was calculated using results of an elemental analysis of the test substance.

Results with reference substance:

The reference substance biodegraded to an extent of 88.7% after 28 days. By Day 3, >60% biodegradation of the positive control was observed, which meets the guideline requirement.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

Hydrocarbons, C12 -C16, n-alkanes, isoalkanes, cyclics <2% aromatics is readily biodegradable.

Executive summary:

Hydrocarbons, C12 -C16, n-alkanes, isoalkanes, cyclics <2% aromatics biodegraded to an extent of 68% after 28 days and 69% after 31 days in an OECD 301F (manometric respirometry), and is therefore considered to be readily biodegradable.

Description of key information

No ready biodegradation test data are available for the registered substance Hydrocarbons, C12-C15 n-alkanes, isoalkanes, cyclics, <2% aromatics (D90), however measured data are available for two substances with carbon ranges similar to the registered substance.

Hydrocarbons, C12-C15, n-alkanes, isoalkanes, <2% aromatics (GS 215) has been tested in an OECD 301F (manometric respirometry) test conducted in compliance with GLP (Vryenhoef, 2014a).

The test substance attained 71% biodegradation in 28 days and the substance is therefore considered to be readily biodegradable.

Hydrocarbons, C12-C16, n-alkanes, isoalkanes, cyclics <2% aromatics biodegraded to an extent of 68% after 28 days and 69% after 31 days in an OECD 301F (manometric respirometry) study, and is therefore considered to be readily biodegradable (ExxonMobil, 1995).

The results from these studies are considered to be reliable and the data are read across to the registered substance Hydrocarbons, C12-C15 n-alkanes, isoalkanes, cyclics <2% aromatics (D90).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable