Docosyltrimethylammonium methyl sulphate

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

26 February - 14 April 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was performed acc. to OECD Guidelines and in compliance with GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Docosyltrimethylammonium chloride

EC Number:

241-327-0

EC Name:

Docosyltrimethylammonium chloride

Cas Number:

17301-53-0

IUPAC Name:

N,N,N-trimethyldocosan-1-aminium chloride

Constituent 2

Reference substance name:

Docosyl tri[14C]methylammonium chloride

IUPAC Name:

Docosyl tri[14C]methylammonium chloride

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):

Activated sludge was obtained from three locations on 26 February 2009; Totnes Sewage
Treatment Works (STW), Devon, UK, Buckland STW, Newton Abbot, Devon UK, and
Countess Weir STW, Exeter, Devon, UK. These STWs all treat sewage of predominantly
domestic origin. At the laboratory, the activated sludge was kept aerated at room temperature.

- Preparation of inoculum for exposure:

The solids concentrations of the three sludges was determined on the day of collection.
Appropriate volumes of each sludge were mixed in order to give similar concentrations of
suspended solids from each sewage treatment works in the final inoculum. The sludge was
then diluted in medium (Section 4.2) to give a total sludge solids concentration in the test of
30 mg/l. This solution was added to test vessels and aerated at test temperature for five days
until required for use.

Reference substance

Reference substance:

benzoic acid, sodium salt

Remarks:

radiolabelled

Results and discussion

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

80

Sampling time:

28 d

Remarks on result:

other: maximum degradation

BOD5 / COD results

Results with reference substance:

In the benzoic acid vessel more than 60% degradation was achieved within the 10 day window as expected for a biodegradable substance, thus confirming that the activated sludge contained viable organisms. By day 35 approximately 83% of the applied radioactivity was measured as [14C]carbon dioxide.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

[14C]C22-ATQ was shown to be readily and ultimately biodegradable, based on carbon dioxide evolution, and based on the criteria for Regulation (EC) 648/2004 (Ref 3)

Executive summary:

	[14C]C22-ATQ	[14C]C22-ATQ + LAS	Ref. substance, [14C]benzoic acid
Lag time	Days 0 to 3	Days 0 to 3	Days 0 to 1
Degradation time	Days 3 to 28	Days 3 to 28	Days 1 to 25
Maximum level of degradation	80%	75%	83%
Readily biodegradable, in compliance with criteria of Regulation (EC) 648/2004	yes	yes	yes

Substantial mineralisation of [14C]C22-ATQ was measured in all the test vessels. The addition of LAS made no discernable difference to the observed degradation. The concentration of [14C]C22-ATQ was below that which would cause inhibition to the activated sludge bacteria, so there was no amelioration of inhibition by the LAS. Benzoic acid was shown to be readily biodegradable, with at least 60% of the applied radioactivity being converted to carbon dioxide by day 7.

Mass Balance:

The mass balance was calculated using the [¹⁴C]carbon dioxide evolution values measured during the study and the additional sampling on Day 35 detailed in Section 4.6, and is shown in Table 2. The total radioactivity recovered from each vessel was between 89 and 102% of the applied radioactivity, with the exception of one of the benzoic acid vessels, where a mass balance of 136% was measured. The sodium hydroxide from this vessel¿s carbon dioxide trap had been accidentally added to the sodium hydroxide from one of the test vessels on day 21. The amount of [¹⁴C]carbon dioxide evolved from this vessel between days 14 and 21 was calculated from the difference between the measurements done on days 14 and 21, but because much more radioactivity was applied to the[¹⁴C]C22-ATQ vessels than to the benzoic acid (approximately 100 times more), this calculated value was subject to large errors. Therefore, the results from only one of the benzoic acid vessels was used for results calculations.

1.1.1                 Radioactivity measured in sludge solids

At the end of the study approximately 18% of the applied radioactivity was measured in the sludge solids from the[¹⁴C]C22-ATQ vessels, and approximately 11% in the sludge solids from the[¹⁴C]C22-ATQ plus LAS vessels.

 

In the benzoic acid reference substance vessels approximately 15% of the applied radioactivity was measured in the sludge solids.

1.1.2                 Radioactivity measured in the filtrate

At the end of the study less than 5% of the applied radioactivity was measured in the filtrate from any of the test or reference substance vessels.

 

1.1.3                 Radioactivity evolved as [¹⁴C]carbon dioxide

A significant amount of mineralisation was measured in all the vessels, as shown in Tables 2 and 3, and Figures 2 to 4.

In the benzoic acid vessel more than 60% degradationwas achieved within the 10 day window as expected for a biodegradable substance, thus confirming that the activated sludge contained viable organisms (Figure 3). By day 35 approximately 83% of the applied radioactivity was measured as[¹⁴C]carbon dioxide.

 

The following phases (approximate) were observed for benzoic acid:

 

Phase	Time period
Lag phase	days 0 to 1
Degradation phase	days 1 to 25
10-day window	days 1 to 11

 

where;

 

Lag phase	Is the period from inoculation until the degradation has increased to 10%
Degradation phase	Is the time from the end of the lag phase to the time when 90% of the maximum level of degradation has been reached
10-day window	The 10 days immediately following the attainment of 10% degradation

 

In the[¹⁴C]C22-ATQ vessels a significant amount of the applied radioactivity was evolved as[¹⁴C]carbon dioxide during the study, reaching between 75 and 80% in the vessels with and without LAS, with no discernable difference between the two treatments. Over 60% biodegradation was observed within 28 days, as shown in Figure 4, so[¹⁴C]C22-ATQ can be classified as ¿readily biodegradable¿, based on the criteria for Regulation (EC) 648/2004 (Ref 3).

 

The following phases (approximate) were observed, for[¹⁴C]C22-ATQ, with and without LAS:

 

Phase	Time period
Lag phase	days 0 to 3
Degradation phase	days 3 to 28
10-day window	days 3 to 13

Mass balance (recovered radioactivity shown as measured value (Bq) and percentage of applied)

Vessel contents	Applied radio-activity (Bq)	Recovered radioactivity
		Carbon dioxide traps		Filtrate		Sludge solids		Total
		Bq	%	Bq	%	Bq	%	Bq	%
[^14C]C22¿ATQ	3140462	2502356	79.7	124376	3.96	593141	18.9	3219873	103
	3140462	2342399	74.6	129043	4.11	565757	18.0	3037199	96.7
[^14C]C22¿ATQ plus LAS	3191703	2376303	74.5	135814	4.26	369177	11.6	2881294	90.3
	3191703	2381277	74.6	159218	4.99	301235	9.4	2841730	89.0
[^14C]Benzoic acid	40370	-^a	-^a	1652	4.09	7929	19.6	-^a	-^a
	40370	33610	83.3	1752	4.34	4553	11.3	39915	98.9

 

a      No result, due to carbon dioxide trap sampling error

Carbon dioxide evolution (% of applied radioactivity)

Vessel contents	Day 3	Day 7	Day 14	Day 21	Day 28	Day 35
[^14C]C22¿ATQ	7.1	26	48	61	72	80
	11	26	48	52	67	75
[^14C]C22¿ATQ plus LAS	8.4	27	51	54	68	74
	8.9	28	49	54	68	75
[^14C]Benzoic acid	52	65	75	107	110	112
	47	60	70	69	80	83