Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Photodegradation:

In the atmosphere rapid degradation takes place by indirect photolysis with OH radicals. The half-life is calculated to be 1.8 hours.

Stability in Water:

The stability of N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD) in aqueous test solution was determined in a hydrolysis test according to OCED Guideline 111 (Hydrolysis as a function of pH). Another test reported the key value for the half-life at environmental relevant conditions (pH7, 25°C) of 3.9 hours. The main hydrolysis product was identified as 4-hydroxydiphenylamine (CAS Nr. 122-37-2) which also was found in the oxidised form p-Benzoquinoneimine-N-phenyl. From these findings IPPD is regarded as rapidly degradable in aqueous media.

Biodegradation:

A test on ready biodegradability was conducted comparable to OECD Guideline 301 B (CO2 -Evolution Test). After 32 days, IPPD showed 18.9 % degradation. Therefore IPPD is not readily biodegradable.

Environmental fate screening (river-die-away-test) of IPPD for biological and chemical transformations was carried out in Mississippi River water (active and sterile) and purified water. The half-live for IPPD in natural water was 2.5 hours.

Bioaccumulation:

Based on the log Kow of 2.77 a BCF of 31.2 was estimated which indicates a low bioaccumulation potential. Although no experimental result for IPPD is available, the QSAR indicates that the substance does not meet the B criterion of 2000.

Due to the rapid hydrolysis of IPPD (half life 3.9 hour), also the hydrolysis product was taken into account.

The BCF of 4 -hydroxydiphenylamine and p-benzoquinoneimine-N-phenyl, the primary hydrolysis products of N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD) were determined in bioconcentrations test that corresponds to OECD Guideline 305 C. The bioconcentration factor ranges from 1.2 - 49.

Transport and distribution:

N-isopropyl-N'-phenylbenzene-1,4-diamine (IPPD) has an adsorption coefficient of LogKoc = 2.39 - 3.64, 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.

The calculated Henry's law constant of 0.000146 Pa*m³/mol indicates that the compound has a low potential for volatilization from surface waters.

The MacKay Level I distribution shows that IPPD is mainly found in the water compartment (about 88%). Low amounts (about 4% each) are distributed to soil and sediment.

A MacKay level III fugacity model (presented in the SIDS report, 2000) 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. Half-life in soil was calculated to be 28.9 hours. 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.