m-phenylenediamine

Endpoint summary

Additional information

 

Physical chemical properties, fugacity modelling, and exposure modelling (see CSR Chapter 9) show that this substance will partition primarily into water. The substance degrades primarily via abiotic processes and to a much lesser extent via biotic processes such as microbial degradation. Abiotic degradation occurs when the substance is exposed to light and oxygen.

 

Rapid photodegradation and oxidation of the substance indicate that the substance is unlikely to persist in air. In addition, the vapour pressure (3.77E-2 Pa) and the Henry's law constant (9.5E-6 Pa m3/mol) of the substance indicate that the substance is not likely to volatilize extensively from surfaces into air under dry conditions or from water. Therefore, any concentrations of the substance in air are considered negligible.

 

Degradation of the substance is also expected in aerobic aquatic environments and water bodies with penetration of natural sunlight. Exposure of the substance to sunlight in water and humic acid amended water demonstrated rapid indirect and direct photodegradation (overall, t½ = 0.51 days). In aerated well water in the absence of natural sunlight, half-lives ranged from 13.4 to 33.6 days. Hydrolysis of the substance is unlikely given the absence of hydrolysable functional groups.

 

Biodegradation is not expected to be a primary route of degradation in the environment. The substance does not readily biodegrade based on activated sludge ready biodegradation studies. Category member, p-phenylenediamine, did not readily degrade in activated sludge as indicated by 30% BOD in a OECD 301D ready biodegradation test after 28 days and no further loss was observed after extending the study to 84 days. The substance did not readily degrade in activated sludge as indicated by a 2% biological oxygen demand observed after 28 days in an OECD 301C study.

 

pKa values < 5 indicate that the substance will exist predominantly in the neutral form in the environment. Therefore, based on the log Kow value (-0.39), sorption to soil, suspended solids and sediment is minimal. Volatilisation from water and moist soil is not expected to be an important fate process for the substance based upon the Henry's Law constant. The vapour pressure indicates that the substance will not volatilise extensively from dry soil (t½= 119 days; see IUCLID 5.4.2 section), however, any substance transferred into the vapour-phase will likely undergo phototransformation.

 

As part of the water surveillance program according to DuPont Asturias IPPC permit, levels of the substance were measured in effluent from the waste water treatment plant at the Asturias S. L. site and in water, sediment, and biota from the estuary over a three year period from 2007 to 2009. No detectable levels of the substance were identified in any of the samples from all locations (see CSR Chapter 9).