Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

N-isopropyl-N'-phenyl-p-phenylenediamine has an adsorption coefficient in the range of LogKoc = 2.39 to 3.64 (Allmendinger 2015a), however is the substance hydrolytically unstable (half-life 3.9 h). 4-Hydroxydiphenylamine (CAS 122-37-2) is the main hydrolysis product. The estimated LogKoc values for 4-hydroxydiphenylamine, using different accepted calculation methods are in the range of 2.41 to 3.03 (Allmendinger 2015b).

The calculated logKoc value from IPPD, is used for the calculation of PNEC concentration for sediment and soil. The lowest Log Koc of the parent substance was chosen as it represent the worst case (gives the highest PNEC in soil and sediment, calculated by EPM)

The calculated Henry's law constant of 0.000146 Pa m³/mol at 25 °C indicates that the compound has only a limited potential for volatilization from surface waters.

The distribution of N-isopropyl-N'-phenyl-p-phenylenediamine in the environment was calculated according to the Mackay fugacity model level I (Allmendinger 2015 d) based on the physico-chemical properties. The main target compartment for N-isopropyl-N'-phenyl-p-phenylenediamine is water with about 88%, followed by soil and sediment with each about 4 %.

A MacKay level III fugacity model (Robertson 2000, presented in the SIDS report) yielded a more detailed description of the substance in the different compartments: The results show that IPPD released via the water phase leads to negligible exposure of the sediment (0.1%) and to no exposure to soil. Released directly to soil will not result in any significant percentages in sediment. It should be mentioned here that direct release to water and soil are the main routes for environmental exposure, concerning manufacture and DU uses as well as the release from tyres.