Quaternary ammonium compounds, bis(hydrogenated tallow alkyl)dimethyl, acetates

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Study period:

April 19, 1990 - February 07, 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Although this study is guideline and GLP compliant and would normally be assigned a reliability of 1 (reliable without restrictions), this study is used for read-across and therefore has been assigned a reliability of 2 (reliable with restrictions).

Justification for type of information:

The primary component of all substances provide complete coverage of 68334-33-8. 68334-33-8 shares high structural similarity with 61789-80-8, 68783-78-8, 107-64-2, and 112-02-7. As 68334-33-8 is a UVCB its components encapsulate the other substances except for the counter ion (Cl-). In solution, the counter ions will dissociate from the parent structures. Therefore, we are comparing substances of equivalent nature. CAS 107-64-2 represents the C18 boundary of the 61789-80-8. Ignoring the salt component CAS 61789-80-8 is equivalent to CAS 68334-33-8. 68783-78-8 is a worst case of both 68334-33-8 and 61789-80-8 since it is unsaturated and the SP2 carbon-carbon bonds are of higher reactivity and a more likely site of metabolic activation. The primary component of CAS 112-02-7 is a substructure of all the other substances. Additional documentation, provided within the IUCLID Assessment Reports section, supports the read-across approach.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

The oxygen depletion in the bottle without inoculation exceeds the values laid down in the guide lines slightly.

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, adapted

Details on inoculum:

Secondary activated sludge was obtained from a plant treating predominately domestic wastewater. The sludge was pre-conditioned to reduce the endogenous respiration rates. To precondition, the sludge (200 mg Dry Weight (DW)/litre) was aerated for a period of one week. The sludge was diluted to a concentration in the BOD bottles of 2 mg DW/litre. Ammonium chloride was omitted from the medium to prevent nitrification. Due to omission the pH of the medium decreased slightly.

Duration of test (contact time):

>= 0 - <= 287 d

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

BOD:ThOD ratio

Details on study design:

TEST CONDITIONS
The sodium acetate was added to the bottles using a stock solution of 1.0 g/litre. A stock suspension of the test substance of 1.0 g/litre was prepared by ultrasonic dispersion. The sludge was diluted to a concentration in the BOD bottles of 2 mg DW/litre. Ammonium chloride was omitted from the medium to prevent nitrification. Due to omission the pH of the medium decreased slightly.

TEST SYSTEM
- Culturing apparatus: The test was performed in 280 ml BOD (Biological Oxygen Demand) bottles.

STATISTICAL METHODS:
The biodegradation was calculated as the ratio of the biochemical oxygen demand (BOD) to the theoretical oxygen demand (ThOD). The ThOD of the test compound is 2.6 g O2/g test substance. The BOD of the test substance and sodium acetate were calculated from the oxygen concentrations in the bottles without and with test substance (B, C) and the bottles without and with sodium acetate (B, D).

Reference substance:

acetic acid, sodium salt

Remarks:

Lot number: B02099

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

38 d

Parameter:

% degradation (O2 consumption)

Value:

68

Sampling time:

287 d

Details on results:

DHTDMAC A4M is not biodegraded in the closed bottle test (28 days). However, in the prolonged closed bottle test DHTDMAC A4 M is biodegraded 68 % at Day 287. The pH of the medium at day 28 is 6.9.

Results with reference substance:

The validity of the test is shown by the oxygen consumption in the control bottle with sodium acetate and an endogenous respiration of 0.4 g/L.

DHTDMAC A4M is not biodegraded in the closed bottle test (28 days). However, in the prolonged closed bottle test DHTDMAC A4 M is biodegraded 68 % at Day 287. The pH of the medium at day 28 is 6.9.

Validity criteria fulfilled:

yes

Remarks:

The test is valid as shown by an endogenous respiration of 0.4 g/L and the total mineralization of the reference compound, sodium acetate.

Interpretation of results:

other: Not readily biodegradable

Conclusions:

DHTDMAC A4M is not readily biodegradable.

Executive summary:

Secondary activated sludge was obtained from a plant treating predominately domestic wastewater. The sludge was pre-conditioned to reduce the endogenous respiration rates. To precondition, the sludge (200 mg Dry Weight (DW)/litre) was aerated for a period of one week. The sludge was diluted to a concentration in the BOD bottles of 2 mg DW/litre. Ammonium chloride was omitted from the medium to prevent nitrification. Due to omission the pH of the medium decreased slightly.

 

DHTDMAC A4M was not biodegraded in the closed bottle test after 28 days (3%). However, in the prolonged closed bottle test DHTDMAC A4 M is biodegraded 68% at Day 287. The pH of the medium at day 28 is 6.9.

Description of key information

Based on 3% degradation with the read-across substance, the test substance is predicted to be not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed