Didecyldimethylammonium chloride

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:

November 18, 2004 - January 18, 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

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):Municipal Sewage treatment plant, D-31137, Hildesheim
- Pretreatment:The activated sludge was washed twice with autoclaved tap water and maintained in an aerobic condition by aeration for 4 hours and then homogenized with a mixer for 2 min. Thereafter the sludge was filtered with folded filter and aerated with CO2-free air for 3 days.50 mL/L were used to initiate the inoculum.
- Concentration of sludge:Not available
- Initial cell/biomass concentration:10E+7-10E+8 CFU/mL
- Water filtered: yes
- Type and size of filter used, if any:Folded filter

Duration of test (contact time):

ca. 28 d

Initial conc.:

10 mg/L

Based on:

act. ingr.

Initial conc.:

66.2 other: %

Based on:

other: TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:Mineral nutrient solution according to OECD 301B guideline
- Test temperature:22±2ºC
- Aeration of dilution water:30-100 mL/min
- Continuous darkness: Low light due to brown glass vessels

TEST SYSTEM
- Culturing apparatus:5000 mL brown glass vessels
- Number of culture flasks/concentration:Two
- Method used to create aerobic conditions:External aeration source at 30-100 mL/min
- Details of trap for CO2 and volatile organics if used:The air outlets of the incubation vessels with the test substance were connected to the CO2 adsorption vessels via a series of 3 gas wash bottles, each containing 100 mL of a 0.0125 mol/L Ba(OH)2 solution. Back titration of the residual Ba(OH)2 was carried out with 0.5 N HCl.

SAMPLING
- Sampling frequency:Days 1, 3, 7, 10, 13, 15, 17, 21, 24, 28 and 29.

CONTROL AND BLANK SYSTEM
- Inoculum blank:Duplicate nutrient solutions
- Toxicity control:Single vessel with the test substance and the reference substance in test concentration

Reference substance:

acetic acid, sodium salt

Remarks:

at 35 mg/L

Preliminary study:

Not applicable

Test performance:

The test was performed without any deviations from the guideline and the study plan.

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 71

Sampling time:

28 d

Remarks on result:

other: for replicate 1

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 67

Sampling time:

28 d

Remarks on result:

other: for replicate 2

Details on results:

The 10% level (beginning of biodegradation) was achieved after 5 days in both the replicates of the test vessel. One replicate reached the pass level of 60% after 15 days, the other repicate reached the pass level after 16 days. The % biodegradation was 72 and 67% for replicate 1 and 2 respectively.

Results with reference substance:

The adaptation phase of the functional control changed after 1 day into the degradation phase (i.e., degradation ≥10%). The course of the degradation phase was rapid and reached a degradation rate of >60% on Day 8. The validity criterion for degradation ≥60% after 14 days is fulfilled.

In the control, a maximum of 46.5 mg CO2/L was formed after 28 days (validity criterion is <70 mg CO2/L after 28 days). In the toxicity control, 57% biodegradation occurred within 13 days and came to a maximum of 76% after 28 days. The biodegradation of the reference was not inhibited by the test substance.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test substance must be regarded as readily biodegradable in the 10-day window and after 28 days.

Executive summary:

A study was carried out to determine the biodegradability of the test substance according to OECD guideline 301B, modified Sturm test. The test substance was tested at 10 mg/L in duplicate vessels, corresponding to a TOC of 6.62 mg/L in the test vessels. The biodegradation of the test substance was followed by titrimetric analysis of the quantity of the CO2 produced by the respiration of the bacteria. The %CO2 production was calculated in relation to the theoretical CO2 of the test substance. The biodegradation was calculated for each titration time.Sodium acetate was used as the functional control to check the activity of the test system. The 10% level (beginning of biodegradation) was achieved after 5 days in both the replicates of the test vessel. One replicate reached the pass level of 60% after 15 days, the other repicate reached the pass level after 16 days. The % biodegradation was 72 and 67% for replicate 1 and 2 respectively. The course of the degradation phase of the functional control was rapid and reached a degradation rate of >60% on Day 8. The validity criterion for degradation ≥60% after 14 days is fulfilled. In the control, a maximum of 46.5 mg CO2/L was formed after 28 days (validity criterion is <70 mg CO2/L after 28 days). In the toxicity control, 57% biodegradation occurred within 13 days and came to a maximum of 76% after 28 days. The biodegradation of the reference was not inhibited by the test substance. The validity criteria of the guideline is fulfilled. The test substance must be regarded as readily biodegradable in the 10-day window and after 28 days.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From Dec 13, 1995 to Jan 18, 1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Details on inoculum:

Nature: River water
Source: River IJssel, The Netherlands
Sampling site: Region of Arnhem, The Netherlands
Laboratory culture: No
Preparation of inoculum for exposure: The river water was preconditioned to reduce the endogenous respiration rates. To this end, 8 L of river
water was aerated for eight days.
Pretreatment: No pre-treatment

Duration of test (contact time):

ca. 28 d

Initial conc.:

4 mg/L

Parameter followed for biodegradation estimation:

other: BOD (biochemical oxygen demand)

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Culturing apparatus: 250 to 300 mL BOD (biological oxygen demand) bottles with glass stoppers.
Number of culture flasks/concentration: 10
Measuring equipment: Oxygen electrode, pH-meter
Test performed in closed vessels due to significant volatility of TS: No
Additional substrate: No
Test temperature: 20 – 22 °C
pH: 8.5 at start, 7.8 at end of test
Aeration of dilution water: No

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

ca. 69

Sampling time:

28 d

Details on results:

The test substance caused no reduction in the endogenous respiration, and is therefore considered to be non-inhibitory to the inoculum. The calculated chemical oxygen demand of the test substance was found to be 1.8 mg/mg. Didecyldimethylammonium chloride was biodegraded 69% at day 28. Hence this compound should be classified as readily biodegradable.

Kinetic of test substance (in %):
= 0 after 0 day(s)
= 36 after 7 day(s)
= 51 after 14 day(s)
= 65 after 21 day(s)
= 69 after 28 day(s)

Kinetic of control substance (in %):
= 77 after 7 day(s)
= 85 after 14 day(s)

Results with reference substance:

Controls with reference substance were carried out:
10 bottles containing sodium acetate (6.7 mg/L) and inoculum.
Inhibition of the degradation of a well degradable compound, e.g. sodium acetate by the test compound in the Closed Bottle Test was not determined because possible toxicity of DDAC to microorganisms degrading acetate is not relevant. Inhibition of the endogenous respiration of the inoculum by the test substance was not detected. Therefore, no inhibition of the biodegradation due to the “high” initial concentration of the test compound is expected.

None

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

DDAC should be classified as readily biodegradable.

Executive summary:

The ready biodegradability of the test substance was determined in a Closed Bottle test according to the slightly modified OECD, EEC and ISO test guidelines under GLP conditions. The test substance caused no reduction in the endogenous respiration in the closed bottles. Hence, it should be regarded as non-inhibitory to the inoculum. The test substance was biodegraded 69% at Day 28, and hence it should be classifed as readily biodegradable. The test was considered as valid as shown by the endogenous respiration at 2.5 mg/L and by the total mineralisation of the reference substance, sodium acetate. The reference substance was degraded 85% after 14 days. Lastly, the oxygen concentrations in all the bottles were >0.5 mg/L during the test period.

Reference 3

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Jul 1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

EU Method C.9 (Biodegradation: Zahn-Wellens Test)

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

other: DIN 38 412 Part 25

Deviations:

not specified

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

Activated slidge from the waste water treatement plant of ARA Kelsterbach/ARA Hoechst 70:30

Duration of test (contact time):

ca. 28 d

Initial conc.:

162 mg/L

Based on:

DOC

Initial conc.:

712 mg/L

Based on:

other: O2 (CSB)

Key result

Parameter:

% degradation (DOC removal)

Value:

ca. 80

Sampling time:

28 d

Remarks on result:

other: > 15 d adaptation time, afterwards rapid degradation. At the beginning, only adsorption to the sludge.

Details on results:

> 15 d adaptation time, afterwards rapid degradation. At the beginning, only adsorption to the sludge.

Interpretation of results:

inherently biodegradable

Conclusions:

Under the test conditions, the test substance was inherently biodegradable.

Executive summary:

A study was conducted to determine the inherent biodegradability of DDAC in a Zahn Wellens test. The substance required over 15 days of adaptation time, after which degradation was rapid (80% after 28 days). At test start, only adsorption to sludge occurred.

Description of key information

Based on the study results, the test substance is considered to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The ready biodegradability of the test substance was determined according to OECD Guideline 301 D (Closed Bottle test) and 301 B (Sturm test) in compliance with GLP. In both studies, the substance was found to be readily biodegradable (Van Ginkel and Pomper, 1996 and Fiebig, 2000). Another study was conducted to determine inherent biodegradability in a Zahn Wellens test (EU Method C.9). The substance required over 15 days of adaptation time, after which degradation was rapid (80% after 28 days). At test start, only adsorption to sludge occurred (Voelkskow, 1989).

Biodegradation mechanism

The pathway of dialkyldimethylammonium salts has been studied with pure cultures. The pure culture, strain DD1, capable of growing on didecyldimethylammonium salt as sole carbon and energy source was isolated from activated sludge. Decyldimethylamine, decanoate, and acetate also served as growth substrates. Dimethylamine was stoichiometrically accumulated during growth on didecyldimethylammonium chloride. These results strongly indicate that the alkyl chains are metabolized sequentially (van Ginkel et al, 2003). Another bacterium is required to degrade the dimethylamine formed (Large, 1971). Nishihara et al (2000) isolated aPseudomonas fluorescensstrain TN4 with didecyldimethylammonium chloride as carbon and energy source. Decyldimethylamine and dimethylamine were identified as intermediates in the biodegradation pathway. Both pure culture studies demonstrate that the degradation of the alkyl chains of dialkyldimethylammonium salts precedes the breakdown of the dimethylamine (Figure). Pseudomonas fluorescensstrain TN4 also degraded other quaternary ammonium salts i.e., alkyltrimethylammonium salts and alkylbenzyldimethylammonium compounds (Nishihara et al, 2000). Strain DD1 was also capable of growing on didodecyldimethylammonium and tetradecyldimethylammonium salts showing broad substrate specificity towards the alkyl chain lengths (van Ginkel et al, 2003). Broad substrate specificities with respect to alkyl chain were demonstrated more comprehensively for other fatty amine derivatives (van Ginkel, 2007[SM1] ).

The Figure 1 in the CSR shows the ability of microorganisms to catalyze C-alkyl-N fissions, thereby forming alkanals that can enter the common pathways of metabolism via β-oxidation (van Ginkel, 2004).

 

Overall, based on the available information, DDAC is considered to be completely mineralised and therefore does notpersist or present a risk to the environment.