1,3,5-tris(3-mercaptopropyl)-1,3,5-triazinane-2,4,6-trione

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:

2017-11-15 to 2018-07-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

July 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The activated sludge derived from a sewage treatment plant to the east of Suzhou city (a conventional treatment plant for domestic waste)
- Sampling date of activated sludge: 2017-11-17
- Concentration of sludge: 30 mg dry solids per litre. The dry solids content of the activated sludge was 4.0 g/L. It was determined by weight measurements after drying at 105°C for 2 hours (mean of 4 replicate measurements).

Duration of test (contact time):

28 d

Initial conc.:

32 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of mineral medium:
a) 8.5051 g KH2PO4, 28.5096 g K2HPO4*3H2O, 67.1801 g Na2HPO4 * 12 H2O, 0.5007 NH4Cl were dissolved in purified water and made up to 1 litre.
b) 18.2010 g CaCl2 * 2H2O was dissolved in purified water and filled up to 0.5 litre.
c) 11.2509 g MgSO4 * 7H2O was dissolved in purified water and filled up to 0.5 litre.
d) 0.125 g FeCl3 * 6H2O was dissolved in purified water, stabilised with one drop of concentrated HCl and filled up to 0.5 litre

For preparation of the mineral medium 80 mL of solution (A) is mixed with purified water, 8 mL each of solutions (B), (C) and (D) are added and the volume is made up to 8 litre with purified water.
The pH was measured to be 7.67 then adjusted to 7.41 with HCl.

- Test temperature: 22 +/- 1 °C
- pH: 7.27-7.50
- Suspended solids concentration: 30 mg/L

TEST SYSTEM
- Test system: OxiTop®- Control from WTW
- Preparation of Test flask: test item was added directly into the test vessels

SAMPLING
- Sampling frequency: at least once a day

CONTROL AND BLANK SYSTEM
- Inoculum blank: 4 replicates
- Abiotic control: 1 replicate
- Toxicity control: 1 replicate
- Reference compound: 1 replicate

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

1.3

Sampling time:

28 d

Results with reference substance:

In the procedure control, the biodegradation percentage of reference item by day 10 was 85.6 %, which was more than 60 %. After 28 days 102.6 % degradation was reached.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The mean biodegradation percentage of test item on day 28 was 1.3 % (calculated based on ThODNH3). Therefore the test item did not reach the pass level for ready biodegradability (60% ThOD within 28 days and 10 d-window). Thus, in this study, the test item 1,3,5-Tris-(3-mercaptopropyl)isocyanurate was not readily biodegradable.

Executive summary:

The biodegradation of 1,3,5-Tris-(3-mercaptopropyl)isocyanurate was studied in a suspension in mineral medium inoculated with activated sludge (30 mg suspended solids/L). The experiment was conducted in accordance with the OECD test guideline 301 F "Manometric Respirometry Test" and in compliance with the OECD-GLP standards.

The system OxiTop®- Control from WTW, Weilheim and the Sensomat-System from Aqualytic GmbH & Co., Langen were used as test systems. 1,3,5-Tris-(3-mercaptopropyl)isocyanurate never reached the pass level for ready biodegradability (60% ThOD in a 10-day window, which begins when the degree of biodegradation reaches 10%). The mean biodegradation percentage of test item on day 28 was 1.3% (calculated based on ThODNH3) Therefore, In this study, the test item 1,3,5-Tris-(3-mercaptopropyl)isocyanurate was not readily biodegradable.

The biodegradation percentage of toxicity control was 28.9% (calculated based on ThOD_NH3) by day 14 (more than 25%), which indicated the test item had toxic inhibition to the inoculum, but the validity criteria of the test at exposure concentration was satisfied.

Description of key information

The mean biodegradation percentage of test item on day 28 was 1.3 % (calculated based on ThODNH3). Therefore the test item did not reach the pass level for ready biodegradability (60% ThOD within 28 days and 10 d-window). Thus, in this study, the test item 1,3,5-Tris-(3-mercaptopropyl)isocyanurate was not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater