Hexahydro-1,3,5-trimethyl-1,3,5-triazine

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:

02 March 2007 to 15 May 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted in accordance with international guidelines in a GLP laboratory. All relevant validity criteria were met.

Qualifier:

according to guideline

Guideline:

OECD Guideline 306 (Biodegradability in Seawater)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water: marine

Details on inoculum:

Seawater was collected from the Burnham-on-Crouch estuary at high water. The Crouch estuary has no industrial and no river inputs. Suspended solids were removed from the raw seawater using a hydro-clone and settlement.Date of collection: 04 April 2007Storage conditions prior to test: Dark, ambient temperatureSalinity at start of test: 31 pptTemperature at start of test: 21.8 °CPre-treatment: Settled, decanted

Duration of test (contact time):

28 d

Initial conc.:

3.04 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Replicate standard BOD bottles were filled with the test concentration, prepared by addition of a sample stock solution to dilution water. A series of test bottles was prepared with dilution water only for the determination of "blank losses". To check the integrity of the test procedure, a readily biodegradable reference material, sodium acetate, was also tested.Initial dissolved oxygen concentrations were measured using a dissolved oxygen meter. The bottles were then incubated in the dark at 20 +/- 1 °C for the test duration. Further measurements of dissolved oxygen concentration were made on bottles removed after 8, 14, 21 and 28 days.

Reference substance:

acetic acid, sodium salt

Remarks:

reported as "sodium acetate"

Preliminary study:

Not applicable

Test performance:

The guideline requires that a the reference material degrades by at least 60 % of it's ThOD, and that the blank dissolved oxygen loss should not exceed 30 % of the initial oxygen concentration. Both of these criteria were satisfied for this test; a maximum value of 79 % was achieved for the reference material and the blank dissolved oxygen loss was 15.9 %.

Key result

Parameter:

% degradation (O2 consumption)

Value:

65

Sampling time:

8 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

73

Sampling time:

14 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

66

Sampling time:

21 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

64

Sampling time:

28 d

Details on results:

The calculated ThOD of the test item was 819 mg O2/g.

Table 1. Dissolved oxygen measurements and calculated BOD values for the test substance and reference material

	Incubation period (days)
	0	8		14		21			28
Incubator temperature (°C)	20.0	21.0		22.0		21.5			21.0
Average blank DO (mg/L)	6.74	6.19		6.46		5.94			5.67
Replicate	1	1	2	1	2	1	2	3	1	2	3
Test substance – DO (mg/L)	6.74	4.56	4.59	4.58	4.52	4.23	4.35	4.33	4.11	4.02	4.07
Test substance – BOD (mg O2/g)	-	536	526	586	605	563	523	530	513	543	526
Reference material – DO (mg/L)	6.77	3.63	3.63	3.25	3.32	3.12	3.06	2.95	2.62	2.74	2.74
Reference material – BOD (mg O2/g)	-	515	515	624	610	567	579	600	612	588	588

Table 2. % Degradation for the test substance and reference substance

	Incubation period (days)
	8		14		21			28
Replicate	1	2	1	2	1	2	3	1	2	3
Test Substance (%)	65	64	71	74	69	64	65	63	66	64
Average Degradation (%)	65		73		66			64
Reference Material (%)	66	66	80	78	73	74	77	79	75	75
Average Degradation (%)	66		79		75			76

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test substance was determined to be radily biodegradable, achieving >60 % biodegradation within 8 days of study initiation and achieving a maximum biodegradation value of 73 % over a 28-day period.

Executive summary:

A study was performed in accordance with OECD Guideline 306 “Biodegradability in Seawater” (Section 5.2.2.) using the closed bottle method. The test item was added to the test vessels from a stock solution and the vessels were filled with seawater with added minerals, and closed ensuring that there was no air filled head space in the vessel. Test vessels containing seawater only (blanks), and vessels containing reference item were also prepared. Initial dissolved oxygen concentrations were measured and the test vessels were then stored in the dark at 20°C for the duration of the test. Further measurements of dissolved oxygen were made after 8, 14, 21 and 28 days.

Hexahydro-1,3,5-trimethyl-1,3,4-triazine achieved 65 % biodegradation by day 8 of the study and a maximum biodegradation of 73 % by day 14. The reference material and blanks were within guideline requirements during the test confirming the validity of the study.

Based on these results, hexahydro-1,3,5-trimethyl-1,3,4-triazine is considered to be equivalent to the category of “readily biodegradable” as described in OECD 301.

Description of key information

Ready Biodegradability = Readily biodegradable, OECD 306, Drake (2007) - See Section 5.2.2.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

marine water

Additional information

A study was performed in accordance with OECD Guideline 306 “Biodegradability in Seawater” (Section 5.2.2.) using the closed bottle method. The test item was added to the test vessels from a stock solution and the vessels were filled with seawater with added minerals, and closed ensuring that there was no air filled head space in the vessel. Test vessels containing seawater only (blanks), and vessels containing reference item were also prepared. Initial dissolved oxygen concentrations were measured and the test vessels were then stored in the dark at 20°C for the duration of the test. Further measurements of dissolved oxygen were made after 8, 14, 21 and 28 days.

Hexahydro-1,3,5-trimethyl-1,3,4-triazine achieved 65 % biodegradation by day 8 of the study and a maximum biodegradation of 73 % by day 14. The reference material and blanks were within guideline requirements during the test confirming the validity of the study.

Based on these results, hexahydro-1,3,5-trimethyl-1,3,4-triazine is considered to be equivalent to the category of “readily biodegradable” as described in OECD 301.