Registration Dossier

Environmental fate & pathways

Phototransformation in air

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

The test substance is covered by the category approach of methylenediphenyl diisocyanates (MDI).

Hence, data of the category substances can be used to cover this endpoint. The read-across category justification document is attached in IUCLID section 13. It is important to note that the MDI category approach for read-across of environmental and human hazards between the MDI substances belonging to the MDI category is work in progress under REACH. Therefore, the document should be considered a draft.

The half-life of 4,4'-MDI/DPG in the atmosphere has been estimated using data from the read-across substance 4,4'-MDI. The AOPWIN (TM)(v1.92) model estimated a half-life of 0.92 days (Pemberton and Tury, 2008).

Key value for chemical safety assessment

Half-life in air:
1 d

Additional information

There are no measured phototransformation data in air for the test substance. The estimated dissipation half-life has been rounded off to 1 day. The exactly calculated value is 0.92 days.

This result was corroborated with a phototransformation analysis of a structural analogue 4-tolylisocyanate (PTI). The phototransformation was determined using the relative rate method where the rates of consumption of PTI relative to a reference compound with a known OH radical rate constant were measured in the presence of OH radical source. The environmental chamber system employed was the Dividable Teflon Chamber. This gave a phototransformation half-life of 0.89 days.