Dichlorotricyclo[8.2.2.24,7]hexadeca-1(12),4,6,10,13,15-hexaene, mixed isomers

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Inoculum or test system:

other: The Secondary effluent of the JRF Sewage Treatment Plant was used as inoculum

Duration of test (contact time):

28 d

Reference substance:

other: Potassium hydrogen phthalate

Parameter:

other: % degradation (based on ThOD)

Value:

3.19

Sampling time:

28 d

Details on results:

The biodegradability of DPX-C (Di-cloro-Di-p-Xililene) was 2.05, 2.05, 2.28 and 3.19% (based on ThOD, i.e., 2.194 mg O2/mg) on day 7, 14, 21, and 28, respectively. After 28 day of analysis, oxygen depletion was < 1.5 mg/L in the inoculum blank. The percent biodegradation data revealed that the DPX-C (Di-cloro-Di-p-Xililene) was not readily biodegradable.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The biodegradability of DPX-C (Di-cloro-Di-p-Xililene) was 2.05, 2.05, 2.28 and 3.19% (based on ThOD, i.e., 2.194 mg O2/mg) on day 7, 14, 21, and 28, respectively. After 28 day of analysis, oxygen depletion was < 1.5 mg/L in the inoculum blank. The percent biodegradation data revealed that the DPX-C (Di-cloro-Di-p-Xililene) was not readily biodegradable. Even though the maximum degradation was 3.19%, whereas the reference substance exhibited a normal pattern of degradation (up to 90.21%) within 28 days. The DPX-C (Di-cloro-Di-p-Xililene) did not inhibit degradation of the reference substance by more than 25% after 14 days. Therefore, DPX-C (Di-cloro-Di-p-Xililene) is not readily biodegradable and nontoxic to microorganisms in the inoculum.

Executive summary:

The ready biodegradability ofDPX-C (Di-cloro-Di-p-Xililene)was determined at a concentration of 2 mg/L in mineral medium inoculated with secondary effluent of a treatment plant (1 mL/L). Potassium hydrogen phthalate was used as a reference substance to check the validity of the method. Mineral medium inoculated with inoculum (1 mL/L) withoutDPX-C (Di-cloro-Di-p-Xililene)and potassium hydrogen phthalate served as inoculum blank. Separate test solutions were maintained contemporaneously (in duplicate) for test, reference and control samples for observation on day 0, 7, 14, 21, and 28.

The value of oxygen depletion was < 1.5 mg/L after 28 day of analysis in the inoculum blank.

During the experiment, the residual concentrations of oxygen in the test bottles on day 28 was 7.78 mg/L (guideline limits > 0.5 mg/L at any time). 

Treatment	% Degradation (Based on ThOD) on days
	7	14	21	28
Test Solution	2.05	2.05	2.28	3.19
Procedure Control	72.77	79.15	83.4	90.21

The value of ThOD for test and reference item was 2.194 mg O₂/mg and 1.175 mg O₂/mg, respectively.

Description of key information

The biodegradability of DPX-C (Di-cloro-Di-p-Xililene) was 2.05, 2.05, 2.28 and 3.19% (based on ThOD, i.e., 2.194 mg O₂/mg) on day 7, 14, 21, and 28, respectively. After 28 day of analysis, oxygen depletion was < 1.5 mg/L in the inoculum blank. The percent biodegradation data revealed that the DPX-C (Di-cloro-Di-p-Xililene) was not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed