Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Adsorption to organic particles:
In view of the adsorption/desorption screening test,
adsorption coefficients on soil for both components of the substance  are:
Koc = 3200 (log Koc = 3,5) for 6PPD
Koc= 25000 (log Koc = 4,4) for p-cumyl-6PPD.
The substance is expected to be immobile in soil [Mensik et al 1995]
Based on the Log Kow, transport of the compound from water to soil/sediment is expected. The values of water solubility
and vapour pressure indicate that the transport from water to air is of low relevance.
Chemical degradation:
The notified substance is an antioxidant and antiozonant and as such necessarily reacts very quickly with oxygen.
Therefore fast oxidation in diluted solution, where oxygen is readily available, is to be expected. Based on the results of modified test of hydrolysis as function of pH it is possible to state that Dusantox L in the aqueous medium is subject to hydrolysis, which is depended on pH and temperature. In buffered aerobic solution at pH 7 and 25°C, the half lives of the two main components 6PPD and cumyl 6PPD are 3,3 and 9 h, respectively, which increased to 4,9 h and 10,2 h at 15°C. The half lives at pH 10 and 25°C are 6,4 and 16,7 which increased to 13,7 h and 31,5 h at 15°C.

As the biodegradation tests clearly show, Dusantox L is not readily biodegradable. The three tests on ready biodegradation ( OECD 301 B, 301 D, 301 F) indicates 46%, 33%, and 9% degradation after 28 days. The used substance concentration 18,2 mg/l and 100 mg/L could not have inhibiting activity on the microbial polulation, since the EC 50 for activated sludge was determined to > 2000 mg/L.