Benzyldimethyl(octadecyl)ammonium chloride

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:

May, 2010

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

KL2 due to RA

Justification for type of information:

Refer to section 13 of IUCLID for details on the read-across justification. The study with the read across substance is considered sufficient to fulfil the information requirements as further explained in the provided endpoint summary.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

acceptable deviations

Principles of method if other than guideline:

Two minor deviations from the guidelines of the Closed Bottle test were introduced; a) ammonium chloride was omitted from the medium to prevent
oxygen consumption due to nitrification (omission does not result in nitrogen limitation as shown by the biodegradation of the reference compound), b) humic acid (4.0 mg/L) was added to reduce the toxicity of the test substance in the test.

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Details on inoculum:

River water was sampled from the Rhine near Heveadorp, The Netherlands (04-02-2010). The nearest plant (Arnhem-Zuid) treating domestic
wastewater biologically was 3 km upstream. The river water was aerated for 7 days before use to reduce the endogenous respiration (van Ginkel and
Stroo, 1992). River water without particles was used as inoculum. The particles were removed by sedimentation.

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Test bottles
The test was performed in 0.30 L BOD (biological oxygen demand) bottles with glass stoppers.

Nutrients and stock solutions
The river water used in the Closed Bottle test was spiked per liter of water with 8.5 mg KH2PO4, 21.75 mg K2HPO4, 33.3 mg Na2HPO4.2H2O, 22.5 mg MgSO4.7H2O, 27.5 mg CaCl2, 0.25 mg FeCl3.6H2O. Ammonium chloride was omitted from the medium to prevent nitrification. Sodium acetate and
the test substance were added to the bottles using stock solution and suspension of 1.0 g/L.

Test procedures
The Closed Bottle test was performed according to the study plan. The study plan was develo¬ped from ISO Test Guidelines (1994). Use was made of 10 bottles containing only river water (inoculum and medium), 10 bottles containing river water and humic acids (4 mg/L), 10 bottles containing
river water, the test substance and humic acid, and 6 bottles containing sodium acetate and river water The concentrations of the test substance
(active) and sodium acetate in the bottles were 2.0 (1.6) and 6.7 mg/L, respectively. Each of the prepared solutions was dispensed into the respective group of BOD bottles so that all bottles were completely filled without air bubbles. The zero time bottles were immediately analyzed for dissolved oxygen using an oxygen electrode. The remaining bottles were closed and incubated in the dark. Two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration at day 7, 14, 21, and 28.

Calculation of the results

Calculation of endogenous respiration
The endogenous respiration (oxygen depletion in the control) was calculated as follows;
Oxygen depletion (endogenous respiration) (mg/L) = Mc (day 0) - Mc (day 28)
Mc is the mean oxygen level in the control bottle inoculated with river water.

Calculation of the theoretical oxygen demand (ThOD)
The ThODs of the test substance, and sodium acetate were calculated from their molecular formulae and molecular weights
The calculated theoretical oxygen demand of the test substance is 2.5 mg/mg. The theoretical oxygen demand of sodium acetate is 0.8 mg/mg.
Calculation of the biochemical oxygen demand (BOD)
Provided that the oxygen concentrations in all bottles at the start of the test were equal, the amounts of oxygen consumed in test and reference
compound bottles were calculated as follows:
Oxygen consumptionn (mg/L) by test substance = Mch - Mt
Oxygen consumptionn (mg/L) by reference compound = Mc - Ma
Mc or ch = the mean oxygen level in the control bottles inoculated with river water, n days after the start of the test (c) or the control
bottles with humic acid (ch).
Mt or a = the mean oxygen concentration in the bottles containing the test substance (t) or the reference compound, sodium acetate (a),
and inoculated with river water, n-days after the start of the test.
The biological oxygen demand (BOD) mg/mg of the test substanceand sodium acetate was calculated by dividing the oxygen consumption by the
concentration of the test substance and sodium acetate in the closed bottle, respectively.

Calculation of the biodegradation percentages
The biodegradation was calculated as the ratio of the biochemical oxygen demand (BOD) to the theoretical oxygen demand (ThOD).

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

64

Sampling time:

28 d

Remarks on result:

other: tested in the presence of humic acid

Details on results:

Toxicity
Inhibition of the degradation of a well-degradable compound, e.g. sodium acetate by the test substance in the Closed Bottle test was not determined
because possible toxicity of quaternary ammonium compounds, benzyl-C16-18-alkyldimethyl, chlorides to microorganisms degrading acetate is notconsidered to be relevant. Humic acid as added to the bottles with quaternary ammonium compounds, benzyl-C16-18-alkyldimethyl, chlorides
because this substance may be toxic to the competent bacteria. Inhibition of the endogenous respiration of the inoculum by the test substance in the presence of humic acid was not detected. Inhibition is usually detected prior to the onset of the biodegradation of the test substance through
suppression of the endogenous respiration (lower oxygen consumption in the presence of a test substance as compared to the control).
The biodegradation of the test substance was already initiated at day 7. Therefore, no inhibition of the biodegradation due to the presence of the test substance is expected.

Test conditions
The pH of the media was 8.0 at the start of the test. The pH of the medium at day 28 was 7.9 (control and test), 8.0 (control with humic acid).
Temperatures were within the prescribed temperature range of 22 to 24°C.

Validity criteria fulfilled:

yes

Remarks:

Endogenous respiration of 1.4 mg/L at day 28. Differences between the replicate values at Day 28 less than 20%. 87% biodegradation of the reference compound, sodium acetate, at Day 14. Oxygen concentrations >0.5 mg/L in all bottles during the test.

Interpretation of results:

readily biodegradable

Conclusions:

Based on the results of the read across study, similar biodegrdation levels can be expected for the test substance.

Executive summary:

A study was conducted to determine the ready biodegradability of the read across substance, C16-18 ADBAC (active: 78%), in water according to OECD Guideline 301, in compliance with GLP. The test was valid as shown by an endogenous respiration of 1.4 mg/L and by the total mineralization of the reference compound, sodium acetate. Sodium acetate was degraded by 87% of its theoretical oxygen demand after 14 d. Finally, the most important criterion was met with the oxygen concentrations being > 0.5 mg/L in all bottles during the test period. Biodegradability was determined to be 64% within 28 d, therefore the substance can be considered readily biodegradable in water. Furthermore, the test substance did not cause a reduction in the endogenous respiration under the chosen test conditions; as such, it is non-inhibitory to the inoculum.The 10-day window pass criterion is not applicable for UVCB surfactant substances.Under the study conditions, the substance was considered to be readily biodegradable (64% in 28 d) under aerobic conditions (van Ginkel, 2010). Based on the results of the read across study, similar biodegradation levels can be expected for the test substance, C18 ADBAC.

Description of key information

Based on the results of the read across study, the test substance, C16-18 ADBAC, is considered to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

A study was conducted to determine the ready biodegradability of the read across substance, C16-18 ADBAC (active: 78%), in water according to OECD Guideline 301, in compliance with GLP. The test was valid as shown by an endogenous respiration of 1.4 mg/L and by the total mineralization of the reference compound, sodium acetate. Sodium acetate was degraded by 87% of its theoretical oxygen demand after 14 d. Finally, the most important criterion was met with the oxygen concentrations being > 0.5 mg/L in all bottles during the test period. Biodegradability was determined to be 64% within 28 d, therefore the substance can be considered readily biodegradable in water. Furthermore, the test substance did not cause a reduction in the endogenous respiration under the chosen test conditions; as such, it is non-inhibitory to the inoculum.The 10-day window pass criterion is not applicable for UVCB surfactant substances. Therefore, under the study conditions, the read across substance was considered to be readily biodegradable (64% in 28 d) (van Ginkel, 2010). Based on the results of the read across study, similar biodegradation levels can be expected for the test substance, C18 ADBAC.

[Type of water: freshwater]