A mixture of: isomers of 2-(2H-benzotriazol-2-yl)-4-methyl-(n)-dodecylphenol; isomers of 2-(2H-benzotriazol-2-yl)-4-methyl-(n)-tetracosylphenol; isomers of 2-(2H-benzotriazol-2-yl)-4-methyl-5,6-didodecyl-phenol. n=5 or 6

Endpoint summary

Description of key information

The test item was degrdaded up to 13 - 19 % after 28 d in water during a modified storm test (OECD 301 B). It was minerlalised up to 1.8 % in a sediment water simulation study (OECD 308). The representative structures of the UVCB are not readily biodegradable. In total 126 metabolites (including the parents) at a quantity >=0.1% and a logKow of > 4 were predicted by QSAR calculations. In addition, four metabolites at a quantity >= 0.1 % have been identified in the biodegradtion study (OECD 308).

Additional information

Biodegradation in water:

According to the key study (CIBA, 1986) the ready biodegradability of the test item was assessed over a 28 day period by the modified Sturm test (OECD 301B). The nominal test concentrations were 10 and 20 mg a.s./L. The test material attained up to 13 and 19 % biodegradation after 28 days whereas the positive control substance (Aniline) was 94.4 % degraded 28 days. These results indicate that the test item cannot be classified readily biodegradable under conditions of the test.

In a supportive study (Ciba, 1986) the Chemical Oxygen Demand was determined. After an exposure of 2 h the amount of O2 was very low, indicating no degradation of the test item.

Supporting calculations with Oasis Catalogic v5.14.1.5 confirmed that the representative structures of the UVCB are not readily biodegradable. In total 126 metabolites (including the parents) at a quantity >=0.1% and a logKow of >4 could be identified.

Biodegradation in water and sediment:

According to the key study (BASF, 2020) following the OECD guideline 308, the biodegradability in a water and sediment simulation test was assessed. The biodegradation was determined by the mineralization of radioactive labelled test material in two different fresh water systems (TS1 and TS2). The results of the study showed that the behavior of the test material in the water/sediment systems is characterized by a fast dissipation from water phase to sediment due to adsorption. During the experimental exposure, no significant mineralization to CO2 was observed indicating that biodegradation of the test material is a slow environmental fate process in both types of water-sediment systems. At the end of exposure, the mean degree of degradation as mineralization was only about 1.8% TAR (total applied radioactivity) in TS1 and 0.3 % TAR in TS2. The half-life of the parent compound for the entire system was 108 d in TS1 and 6.2 d for TS2 at a temperature of 21.6 °C. No major metabolites (> 10% TAR) were identified during the experimental exposure. But, a total of 31 minor metabolites above 0.1% TAR were observed in the water as well as sediment phase of both TS1 and TS2, four of them were identified.

The biomass and the other parameters measured in the control at the end of exposure showed that the systems were stable and active during the exposure time. No inhibition effect to microorganism in the test vessels were found in the inhibition test vessels.