Decanoic acid, mixed diesters with octanoic acid and propylene glycol

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:

11 Jul - 10 Aug 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

yes

Remarks:

Temperature exceeded 24 °C on one day of the test

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: obtained from sewage treatment plant 'Marl Ost', Germany (11 Jul 1995)
- Initial cell/biomass concentration: 102*10^4 colony-forming units/mL
- Other: dry weight of inoculum: 4.2 g/L

Duration of test (contact time):

29 d

Initial conc.:

21.2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium according to guideline 92/69/EWG C.4-C
- Test temperature: 22.2 - 24.2 °C
- pH: 7.6 - 7.7 after 28 d
- Suspended solids concentration: 28.0 mg/L

TEST SYSTEM
- Culturing apparatus: 5 L glass vessels
- Number of culture flasks/concentration: 2
- Measuring equipment: TAC analyser (Shimadzu)
- Details of trap for CO2 and volatile organics if used: sodium hydroxide solution
- Other: 2.4 L of constantly aerated mineral medium was added to each vessel, incoulated and filled-up to a final volume of 3 L. The test vessels were acidified to eliminate the remaining dissolved CO2 on day 28. The bacteria were crucified and the degradation was stopped. The biodegradation rate obtained on day 29 was allocated to the result on day 28.

SAMPLING
- Sampling frequency: days 0, 2, 5, 8, 14, 19, 23, 28, 29

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates
- Other: positive control: sodium benzoate, 1 bottle

Reference substance:

benzoic acid, sodium salt

Remarks:

concentration: 25 mg/L

Parameter:

% degradation (CO2 evolution)

Value:

82

Sampling time:

28 d

Details on results:

Within the 10-day window the 60% level was passed. Therefore, the test substance is regarded as readily biodegradable.

Results with reference substance:

The reference substance is degraded by 89% after 28 days and it meets the 10-day window requirement.

The temperature exceeded 24 °C on one day of the test. This has not affected the outcome of the study since the biodegradation of the reference substance was normal.

Table 1: Biodegradation (%) of test substance (TS) and reference substance (RS)

Day	TS I	TS II	TS Mean	RS
0	0	0	0	0
2	22	16	19	45
5	57	53	55	70
8	59	68	69	80
14	78	78	78	85
19	80	81	81	85
23	81	79	80	88
28	82	81	82	88
29	83	82	83	89

Table 2: Validity criteria for OECD 301B.

Criterion from the guideline	Outcome	Validity criterion fulfilled
Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.	Difference of extremes of replicate values of the removal of the test chemical were less than 20% at all times.	yes
Percentage degradation of the reference compound reached the pass level by day 14 (≥ 60%).	85%degradation of the reference compound by day 14.	yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	no toxicity control performed	-
The IC content of the test substance suspension in the mineral medium at the beginning of the test must be less than 5% of the TC.	TC was not determined.	-
The total CO2 evolution in the inoculum blank at the end of the test should not normally exceed 40 mg/L medium.	The total CO2 evolution in the inoculum blanks at the end of the test was 14.52 and 15.20 mg/L.	yes

 

Validity criteria fulfilled:

yes

Remarks:

See Table 2 in "Any other onformation on results incl. tables".

Interpretation of results:

readily biodegradable

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

15 Apr - 13 May 1994

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

yes

Remarks:

Temperature was not in the range of 22 ± 2 °C

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: secondary effluent from activated-sludge plant

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge plant at URL North (unacclimatised)
- Pretreatment: The level of dissolved inorganic carbon (DIC) was reduced by sparging the filtered effluent with nitrogen after prior adjustment of the pH to 6.5.
- Water filtered: yes
- Type and size of filter used, if any: Whatman filter paper (541)

Duration of test (contact time):

28 d

Initial conc.:

9.99 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Test temperature: 16 - 21 °C
- pH: The pH of the inoculum was adjusted to 6.5
- pH adjusted: yes

TEST SYSTEM
- Culturing apparatus: 160 mL hypovials containing 100 mL mineral salts medium inoculated with secondary effluent and the respective test or reference substance. The sealed vessels were incubated at 20 °C on a rotary shaker. The headspace in each vessel has a volume of 60 mL and, when filled with air, contains approx. 6 times the mass of oxygen required for the complete oxidation of the substance.
- Number of culture flasks/concentration: multiple vessels
- Measuring equipment: Ionics 555 Inorganic Carbon Analyser to analyse the CO2/DIC in the headspace gas and the liquid medium. The total inorganic carbon in the vessel is calculated and corrected by subtracting the total inorganic carbon produced in a control.

SAMPLING
- Sampling frequency: Sampled on day 4, 7, 11, 14, 18, 21 and 28
- Sampling method: One vessel per substance and control was analysed except on day 28 when five vessels were analysed

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

Reference substance:

benzoic acid, sodium salt

Remarks:

concentration: 10 mg DOC/L

Parameter:

% degradation (CO2 evolution)

Value:

104.5

Sampling time:

28 d

Remarks on result:

other: 95% CL: 99.9 - 109.2%

Details on results:

Within the 10-day time window the 60% level was passed. Therefore, the test substance is regarded as readily biodegradable.

Results with reference substance:

Degradation: 89.8% after 28 days, 60% pass level was reached within 10 days.

Two biodegradation on day 21 and 28 were > 100%. These test vessels were probably contaminated with organic material.

Table 1: Percentage biodegradation over 28 day test period

Day No.	Control vessel µg IC	% biodegradation of test substance
4	40.6	60.4
7	58.6	89.3
11	59.7	94.7
14	81.7	101.8
18	106.9	99.3
21	71.1	105.4
28 (mean)	118.6	104.5
95% Confid. Limits	not determined	99.9 - 109.2

Table 2: Validity criteria for OECD 301B.

Criterion from the guideline	Outcome	Validity criterion fulfilled
Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.	Information on replicates is not given.	-
Percentage degradation of the reference compound reached the pass level by day 14 (≥ 60%).	>90% degradation of the reference compound by day 14.	yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	No toxicity control was performed.	-
The IC content of the test substance suspension in the mineral medium at the beginning of the test must be less than 5% of the TC.	Information on TC is not given.	-
The total CO2 evolution in the inoculum blank at the end of the test should not normally exceed 40 mg/L medium.	The total CO2 evolution in the inoculum blank at the end of the test 1.2 mg/L medium.	yes

 

Validity criteria fulfilled:

not specified

Remarks:

See Table 2 in "Any other onformation on results incl. tables".

Interpretation of results:

readily biodegradable

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

29 Jun - 27 Jul 1993

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

yes

Remarks:

Temperature was not in a range of 22 ± 2 °C

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: 10% by volume of activated sludge plant secondary effluent

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge plant at URL North, UK
- Water filtered: yes
- Type and size of filter used, if any: Whatman filter paper (541)
- Other: The level of dissolved inorganic carbon (DIC) was reduced by sparging the filtered effluent with nitrogen after prior adjustment of the pH to 6.5.

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral salts medium according to guideline OECD 301B
- Test temperature: 19 - 23 °C

TEST SYSTEM
- Culturing apparatus: 160 mL vessel (hypovials)
- Number of culture flasks/concentration: multiple vessels (one was analysed each day except on day 28 when five vessels were analysed)
- Method used to create aerobic conditions: incubated on a rotary shaker
- Measuring equipment: Ionics 555 Inorganic Carbon Analyser
- Test performed in closed vessels due to significant volatility of test substance: sealed with butyl rubber septum and aluminium crimp seal


SAMPLING
- Sampling frequency: on day 3, 7, 10, 14, 17, 21, 24 and 28
- Sampling method: Concentration of CO2 was determined in the headspace gas. The seal is then broken and the inorganic carbon concentration in the test medium is also determined.


CONTROL AND BLANK SYSTEM
- Inoculum blank: multiple vessels (one was analysed each day except on day 28 when five vessels were analysed)
- Abiotic sterile control: no
- Toxicity control: no

Reference substance:

benzoic acid, sodium salt

Remarks:

concentration: 10 mg DOC/L

Parameter:

% degradation (CO2 evolution)

Value:

107.6

Sampling time:

28 d

Remarks on result:

other: 95% CL: 99.1 - 116.1%

Details on results:

Within the 10-day time window the 60% level was passed. Therefore, the test substance is regarded as readily biodegradable.

Results with reference substance:

99.5% after 28 days, 60% pass level was reached.

Two control vessels on day 24 (one vessel) and 28 (one vessel) gave very high inorganic carbon values (IC) of 345 and 372.6 µg, respectively. These test vessels were probably contaminated with organic material. Since only one vessel was analysed on day 24, the biodegradation is lower then expected on this day. On day 28, replicates were analysed and the high IC value was excluded from calculation using Dixon’s test.

Table 1: Percentage biodegradation over 28 day test period

Day No.	Control vessel µg IC	% biodegradation of test substance
3	37.8	60.4
7	79.4	97.8
10	103.0	88.2
14	79.6	98.1
17	78.9	101.9
21	171.3	94.1
24	345.0	72.5
28 (mean)	95.9	107.6
95% Confid. Limits	not determined	99.1 – 116.1

Table 2: Validity criteria for OECD 301B.

Criterion from the guideline	Outcome	Validity criterion fulfilled
Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.	Information on replicates is not given.	-
Percentage degradation of the reference compound reached the pass level by day 14 (≥ 60%).	>90% degradation of the reference compound by day 14.	yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	No toxicity control was performed.	-
The IC content of the test substance suspension in the mineral medium at the beginning of the test must be less than 5% of the TC.	Information on TC is not given.	-
The total CO2 evolution in the inoculum blank at the end of the test should not normally exceed 40 mg/L medium.	The total CO2 evolution in the inoculum blank at the end of the test 0.95 mg/L medium.	yes

 

Validity criteria fulfilled:

not specified

Remarks:

See Table 2 in "Any other onformation on results incl. tables".

Interpretation of results:

readily biodegradable

Description of key information

Readily biodegradable: ≥ 60% in 28 days

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Three studies are available to evaluate the readily biodegradability of decanoic acid, mixed diesters with octanoic acid and propylene glycol (CAS 68583-51-7).

The first study (1995) was conducted according to the EU Method C.4-C (GLP) under aerobic conditions using domestic activated sludge as inoculum. A mean biodegradation of 82% was observed after 28 d. Since the substance reached the pass level (biodegradation is > 60% within the 10-day window) the test substance is considered to be readily biodegradable according to the OECD criteria.

This result is supported by two GLP-Guideline studies with decanoic acid, mixed diesters with octanoic acid and propylene glycol according to OECD 301B using secondary effluent from an activated-sludge plant as inoculum. A mean biodegradation of 104.5 and 107.6%, respectively, and the fulfilment of the 10-day window criterion consider the substance to be readily biodegradable.