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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

ITC 288/S is not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Three studies are available. Two of them are ready biodegradability tests, performed according to the OECD TG 301C (Safepharm 1997) and 301D (Safepharm 1992) respectively, and the third one is a biodegradability study in sea water according to the OECD TG 306 (Safepharm 2007). All of these three studies followed the GLP.

The two ready biodegradability tests concluded that ITC 288/S is not readily biodegradable. The study performed according to the OECD TG 301D was considered as reliable with restrictions due to some lack of data on the test material and test conditions and as the substance has been tested at a higher concentration than the one recommended in the TG. It has been selected as supporting study. The study conducted according to the OECD TG 301C was considered as reliable without restrictions and selected as key study. It can be summarised as follows:

The oxygen uptake by a stirred solution of ITC 288/S in a mineral medium inoculated with a mixed population of activated sludge microorganisms from ten different sampling sites has been measured automatically. Considering a theoritical oxygen demande of 42 mg O2/L at 100 mg ITC 288/L, this oxygen uptake gave a biodegradation of 9% in 28 days.

No degradation was observed in the abiotic control and Aniline attained 42% degradation after 7 days and 79% degradation after 14 days, confirming the suitability of the inoculum and culture.

Dissolved Organic Carbon (DOC), was measured on days 0 and 28 and showed 23% of biodegradation of ITC 288/S in presence of the inoculum, no degradation of ITC 288/S in deionised water (i.e. abiotic control) and 99% of biodegradation of Aniline.

Chemical Oxyden Demand (COD) was measured on days 0 and 28 and showed 23% of biodegradation of ITC 288/S in presence of inuculum and 100% of biodegradation of Aniline.

Compound specific analysis of the test material was carried out on days 0 and 28 by ion chromatography. It gaves 2% of biodegradation of ITC 288/S in presence of the inoculum and no degradation of ITC 288/S in deionised water (i.e. abiotic control).

Based on these results, ITC 288/S was not readily biodegradable under the test conditions.

The third study on biodegradability in sea water has been considered as reliable without restriction and as supporting study. It can be summarised as follows: the biodegradability of ITC 288/S in sea water was investigated in a "Closed bottle test". In the test flasks, containing the test substance ITC 288/S at 15 mg/L and sea water (inoculum), 22% of biodegradation was observed (based on the mean oxygen consomption) within the test period of 28 days.

The oxygen depletion in the control vessels was 11% of the initial DOC and the residual oxygen concentration remained at 3.6 mg O2/L or greater in all test vessels, thereby satisfying the validation criteria for oxygen depletion.

The standard material, sodium benzoate, attained 66% degradation after 14 days and 69% degradation after 28 days thereby confirming the suitability of the test method and culture conditions.

The toxicity control attained 37% degradation in 28 day. The degradation rate in the toxicity control was lower than that expected based on the sum of the oxygen depletion values for the test and standard material. This effect was considered to be due to the marine micro-organisms present in the test medium being unable to degrade both the sodium benzoate and test material present simultaneously and hence the low degradation rate. However, the results of this and the test material vessels, clearly showed that the test material was not toxic to the micro-organisms present.

Based on these results, ITC 288/S cannot be considered to have a potential for biodegradation in the marine environment under the terms and conditions of OECD Guideline No 306.