Quaternary ammonium compounds, coco alkyltrimethyl, chlorides

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:

From 26 November, 1988 to 29 December, 1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

Deviations: -Instead of an effluent/extract/mixture, activated sludge was used as an inoculums -ammonium chloride was omitted from the medium to prevent nitrification -the course of the oxygen decrease was measured in one bottle using a special funnel

Qualifier:

according to guideline

Guideline:

other: EEC, 1984: “Official Journal of the European communities” L251, 1984.09.19. Part C. Methods for the determination of ecotoxicity, C Degradation biotic degradation: Closed bottle test.

GLP compliance:

no

Remarks:

No, although the study was not performed under GLP it was performed in a GLP lab by the same people with the GLP experience and equipment under the same circumstances as the GLP studies

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Secondary activated sludge was obtained from the RZWI Nieuwgraaf at duiven (1988.11.26). The RZWI Nieuwgraaf is an activated sludge plant treating predominantly domestic waste water.

Duration of test (contact time):

ca. 28 d

Initial conc.:

3 mg/L

Based on:

act. ingr.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

The test was performed in 250 to 300 mL BOD bottles. The test substance was added to an aqueous solution of mineral salts and exposed to relatively low number of microorganisms under aerobic conditions for a period of 28 days.The dissolved oxygen concentration were determined electrochemically using an oxygen electrode and meter.

Reference substance:

acetic acid, sodium salt

Remarks:

at 5 mg/L

Parameter:

% degradation (O2 consumption)

Value:

59

Sampling time:

5 d

Parameter:

% degradation (O2 consumption)

Value:

74

Sampling time:

17 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

75

Sampling time:

28 d

Details on results:

As evident from the biodegradation of 59% at Day 5 and 74% at Day 17, the plateau for ready biodegradability of the test substance was reached within 14 d of time point when 10 % degradation occurred. The 14 d window was therefore achieved.

Results with reference substance:

For the reference substance, the biodegradation was 82% after 28 d.

Oxygen consumption in the presence of the test substance and sodium acetate:

Time (days)	5	15	28
Test substance (mg O2/L)	4.9	6.1	6.2
Sodium acetate (mg O2/L)	3	3.2	3.2

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under the test conditions, the test substance showed 75% degradation in 28 d and was considered to be readily biodegradable.

Executive summary:

A study was conducted to determine the ready biodegradability of the test substance, TMAC C, according to OECD 301D and EEC Guidelines using a closed bottle test. The test substance at 3 mg/L was incubated with sludge from an activated sludge plant treating predominantly domestic waste and O2 consumption was determined for 28 d. The biodegradation was calculated as the ratio of the biochemical oxygen demand to the theoretical oxygen demand. The test substance reached a biodegradation of 75% on Day 28. As evident from the biodegradation of 59% at Day 5 and 74% at Day 17, the plateau for ready biodegradability of the test substance was reached within 14 d of the time point when 10% degradation occurred. Under the test conditions, the test substance is readily biodegradable (van Ginkel, 1989).

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 12 December, 1986 to 4 February, 1987

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

The method was modified acording to the recommendations of ECETOC (1985) or Blok et al. (1985).

Deviations:

not specified

Principles of method if other than guideline:

The solution of the test substance in mineral medium, usually at 2-5 mg/l, was inoculated with a relatively small number of micro-organisms from a mixed population and kept in completely full, closed bottles in the dark at constant temperature. Degradation was followed by analysis of dissolved oxygen over a 28-d period. The amount of oxygen taken up by the microbial population during biodegradation of the test substance, corrected for uptake by the blank inoculum run in parallel, was expressed as a percentage of ThOD or, less satisfactorily COD.

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

The inoculum was taken from an activated sludge plant, the water treatment plant in Duiven (NL). The sludge was preconditioned during a week: a sludge suspension of 1 g s.s./l was aerated in the dilution water. This modification was introduced to reduce high residual respiration rates. The density of the inoculum in the test was 3 mg s.s./l. On day 0, 14, 28 and 42 the concentration of oxygen was measured. On day 28, nitrite and nitrate concentrations were measured. The dilution water was the medium as prescribed by the test guideline without ammonia. This modification was introduced to minimize the consumption of oxygen for the nitrification process.

Duration of test (contact time):

ca. 2 - ca. 6 wk

Initial conc.:

6.1 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Biodegradability test
The biodegradability test was carried out according to OECD Test Guideline 301D: Closed Bottle Test. The method was modified according to the recommendations of ECETOC (1985) or Blok et al. (1985). Modifications concern the inoculum, the composition of the dilution water and the analyses. The inoculum was taken from an activated sludge plant, the water treatment plant in Duiven (NL). The sludge was preconditioned during a week: a sludge suspension of 1 g s.s./L was aerated in the dilution water. This modification was introduced to reduce high residual respiration rates. The density of the inoculum in the test was 3 mg s.s./L. On Day 0, 14, 28 and 42 the concentration of oxygen was measured. On Day 28, nitrite and nitrate concentrations were measured. The dilution water was the medium as prescribed by the test guideline without ammonia. This modification was introduced to minimize the consumption of oxygen for the nitrification process. Dark glass bottles of about 280 mL with glass stoppers were filled completely with a suspension of preconditioned activated sludge (3 mg s.s/L) in dilution water and a concentration of the test substance equivalent to about 6 mg ThOD/L (Theoretical Oxygen Demand). The test was carried out in triplicate and at every observation time measurements of oxygen and pH were carried out in a new series of three bottles.
According to the OECD expert group on degradation accumulation (1981), a substance may be regarded as readily biodegradable if within 28 days the biodegradation, measured as BOD/ThOD has passed 60%. In this study, measured COD was used for the calculations.

Reference substance:

acetic acid, sodium salt

Parameter:

other: Percentage degradation based on BOD5/COD ratios

Value:

ca. 90 - ca. 97

Sampling time:

28 d

Remarks on result:

other:

Remarks:

readily biodegradable

Details on results:

ThOD = 0.97 mg o2/mg
COD = 0.68 mg o2 / mg
Theconcentration in the test= 6.1 mg Arquad/l,
therefore, the COD test suspension = 4.15 mg o2/l.
 
Toxicity
The oxygen consumption caused by the biodegradation of NaAc during one week was 8.68-3.92 =4.8 mg o2/l. The consumption of oxygen for the biodegradation of NaAc was not inhibited by concentrations of 6.1 and 18.3 mg/I.
 
Biodegradation
The extra consumption of oxygen as compared to the blank (Biochemical Oxygen Demand, BOD) can be attributed to the biodegradation of the test substance. The extent of biodegradation, calculated as the BOD related the COD for test substance was 90% or more after 2, 4 and 6 weeks.

Key result

Parameter:

BOD5*100/COD

Value:

ca. 90 - ca. 97

Table 1: Measurements of oxygen concentration, pH and calculated percentage of degradation

Week	Blank	Test substance	Extra O2 consumption	BOD/COD = % Biodegradation
2	8.40	4.70	3.73	3.73/4.15 = 90 %
	8.42	4.49
	8.41	4.85
Mean	8.41	4.68
pH	7.1	6.9
4	8.15	4.25	4.01	4.01/4.15 = 97 %
	8.21	4.02
	8.05	4.12
Mean	8.14	4.13
pH	7.1	7
6	7.66		4.04	4.04/4.15 = 97 %
	7.62	4
	8.22	4.05
	8	3.45
Mean	7.88	3.83
pH	6.9	6.7

After 4 weeks, the nitrite concentration was <0.1 mg/l and the nitrate concentration was <1.5 mg/l.

Table 2: Concentration of oxygen after 7 days

	Blank	NaAc	Test substance
		14.6 mg/l	6.1 mg/l	18.3 mg/l
	mg O2/l
	8.65	4.09	0.83	1.70
	8.72	3.87	0.82	*
	8.68	3.79	1.97	3.75
mean	8.68	3.92	1.21	2.73
pH	6.9	6.8	6.7	6.7

*Leaking bottle

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under study conditions, the test substance was considered to be readily biodegradable.

Executive summary:

A study was conducted to determine the biodegradability of the test substance, TMAC C (34% Coco TMAC in water), according to the OECD 310D by closed bottle test, in an aerobic activated sludge test system. The method was modified according to the recommendations of ECETOC (1985) or Blok et al. (1985). In the experiment, dark glass bottles of about 280 mL with glass stoppers were filled with a suspension of preconditioned activated sludge (3 mg s.s/L) in dilution water and a concentration of the test substance equivalent to about 6 mg ThOD/L (Theoretical Oxygen Demand). The test was carried out in triplicate and at every observation time measurements of oxygen and pH were carried out in a new series of three bottles. The percentage degradation calculated based on measured BOD/COD values at 2, 4 and 6 weeks, was found to be 90%, 97% and 97% respectively. Based on the results, it was concluded that the test substance passed the OECD criteria of 60% to classify the substance as readily biodegradable. Therefore, under the study conditions, the test substance was considered to be readily biodegradable (Balk, 1987).

Description of key information

Based on the results from the available studies, the test substance is concluded to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Study 1: A study was conducted to determine the ready biodegradability of the test substance, TMAC C, according to OECD 301D and EEC Guidelines using a closed bottle test. The test substance at 3 mg/L was incubated with sludge from an activated sludge plant treating predominantly domestic waste and O2 consumption was determined for 28 d. The biodegradation was calculated as the ratio of the biochemical oxygen demand to the theoretical oxygen demand. The test substance reached a biodegradation of 75% on Day 28. As evident from the biodegradation of 59% at Day 5 and 74% at Day 17, the plateau for ready biodegradability of the test substance was reached within 14 d of the time point when 10% degradation occurred. Under the test conditions, the test substance is readily biodegradable (van Ginkel, 1989).

 

Study 2: A study was conducted to determine the biodegradability of the test substance, TMAC C (34% TMAC C in water), according to the OECD 310D by closed bottle test, in an aerobic activated sludge test system. The method was modified according to the recommendations of ECETOC (1985) or Blok et al. (1985). In the experiment, dark glass bottles of about 280 mL with glass stoppers were filled with a suspension of preconditioned activated sludge (3 mg s.s/L) in dilution water and a concentration of the test substance equivalent to about 6 mg ThOD/L (Theoretical Oxygen Demand). The test was carried out in triplicate and at every observation time measurements of oxygen and pH were carried out in a new series of three bottles. The percentage degradation calculated based on measured BOD/COD values at 2, 4 and 6 weeks, was found to be 90%, 97% and 97% respectively. Based on the results, it was concluded that the test substance passed the OECD criteria of 60% to classify the substance as readily biodegradable. Therefore, under the study conditions, the test substance was considered to be readily biodegradable (Balk, 1987).

 

 

Based on the above studies, the Biocides assessment report on TMAC C, published by the Italian authorities in April 2016, also concluded:“Coco alkyltrimethylammonium chloride is readily biodegradable. Further studies are not necessary because it is readily biodegradable applies.”(ECHA biocides assessment report, 2016).     

Further, the results obtained with the test substance are in agreement with what is reported in the literature for other quaternary ammonium substances, as summarized below inTable 4.4.

Table 4.4. Compilation of ready biodegradability test results obtained with quaternary ammonium salts (adapted van Ginkel, 2007)

Substance	Test	Results at Day 28 (%)
Cocotrimethylammonium (TMAC C)	Closed bottle	>60
Hexadecyltrimethylammonium Chloride (C16 TMAC)	Headspace Carbon Dioxide	75*
Octadecyltrimethylammonium Chloride (C18 TMAC)	Sturm test	>70
Octylbenzyldimethylammonium chloride (C18 ADBAC)	MITI	>80
Tetradecylbenzyldimethylammonium Chloride (C14 ADBAC)	MITI	>80
Decylbenzyldimethylammonium Chloride (C10 ADBAC)	Closed bottle	>60

*Mean from 10 laboratories; also cited in OECD TG 310 (adopted on 23 March 2006)

Biodegradation pathways of quaternary substances

Several literature data are available to clarify the metabolic basis of degradation by micro-organisms. Bacteria identified as Pseudomonas sp capable of degrading alkyltrimethylammonium salts were isolated from activated sludge (van Ginkelet al., 1992; Takenakaet al., 2007). Alkyltrimethylammonium salts with octadecyl, hexadecyl, tetradecyl, dodecyl, decyl, octyl, hexyl and coco alkyl chains supported growth of the isolates, showing the broad substrate specificity with respect to the alkyl chain length. Alkanals, and fatty acids can also serve as a carbon and energy source (van Ginkelet al., 1992; Takenakaet al., 2007). In simultaneous adaptation studies,1H nuclear magnetic resonance spectrometry (1H-NMR) and GC-MS showed that acetate, alkanals and alkanoates are the main intermediates of alkyltrimethylammmonium salt degradation, indicating that the long alkyl chain is utilized for microbial growth (van Ginkelet al., 1992; Nishiyama and Nishihara, 2002; Takenakaet al., 2007). Trimethylamine is stoichiometrically produced by pure cultures of microorganisms growing with the alkyl chain of alkyltrimethylammonium chloride as the sole source of carbon. The cleavage of the C-alkyl-N bond of alkyltrimethylammonium salts resulting in the formation of trimethylamine is initiated by a mono-oxygenase (van Ginkelet al., 1992). Additional evidence of the cleavage of the C-alkyl-N bond as the initial degradation step of alkyltrimethylammonium salts was presented by Nishiyamaet al. (1995) and Takenakaet al. (2007).

Dehydrogenase activity present in cell-free extract of hexadecyltrimethylammonium chloride-grown cells catalysed the oxidation of alkanal to fatty acids. The route of the fatty acid degradation is by β-oxidation. Trimethylamine, a naturally occurring compound is readily biodegradable (Pitter and Chudoba 1990). Complete degradation of trimethylamine is demonstrated through the assessment of the biodegradation pathway. Trimethylamine is degraded by methylotrophic bacteria through successive cleavage of the methyl groups (Large, 1971; Meiberg and Harder, 1978). Consortia of microorganisms degrading the alkyl chain of alkyltrimethylammonium salts and trimethylamine are therefore capable of complete (ultimate) degradation of alkyltrimethylammonium salts. Complete degradation of alkyltrimethylammonium salts using a mixed culture has been demonstrated by Nishiyamaet al. (1995). More recently, Nishiyama and Nishihara (2002) have isolated aPseudomonas spcapable of degrading both the alkyl chain and trimethylamine.  Both the pure and mixed culture studies showed that the degradation of the alkyl chain of alkyltrimethylammonium salts results in the formation of water, carbon dioxide and ammonium (seeFigure 2).

 

Figure 2: Biodegradation pathway of alkyltrimethylammonium salts (van Ginkel, 2004, 2007)

Further, according to the evidence presently available on the biodegradation rate, microorganisms readily oxidize the hydrophobic alkyl chains of the cationic surfactants, which is followed by a slower oxidation of the hydrophilic moiety (the corresponding amines) (van Ginkel, 2004). The above biodegradation process for the two moieties plays a key role in the differences in the results between the different cationic surfactants. However, based on the available experimental data and literature evidence, the alkyl chains and the trimethylamine of the test substance is readily biodegradable.

Overall, considering all the above information together, the test substance is considered to be readily biodegradable undergoing complete mineralization.