Diisotridecyl phenyl phosphite

Endpoint summary

Description of key information

The environmental fate properties of phenyl diisotridecyl phosphitee (PDiTDP) and related alkyl and phenyl phosphites generally include: low water solubility, low vapour pressure, and rapid hydrolysis to phosphorous acid and corresponding alcohols (in the case of PDiTDP it is isotridecanol (C13 alkyl alcohol) and phenol).

 

A biodegradation screening study, OECD 301D Closed Bottle Test, was performed by van Ginkel (2014) on TiTDP, a very close analog to PDiTDP, to evaluate the persistence of TiTDP and also to compare the rate of biodegradation of TiTDP to that of its primary hydrolysis product – isotridecyl alcohol. The results of the new OECD 301D study found 57% degradation at 28 days, with degradation continuing to 63% degradation at 42 days. Whilst these results do not fully meet the ready biodegradable standard, they demonstrate that TiTDP is inherently biodegradable and not persistent. The rate of biodegradation of TiTDP is somewhat slower than that of isotridecyl alcohol, which does meet the ready criterion. This is probably due to the additional time needed for hydrolysis to occur and also for the greater sorption potential of the phosphite vs. the alcohol, which can also delay the biodegradation process.

Bioaccumulation concentration factor (BCF) estimates for PDiTDP vary by a large range from 89.98 to 3.87e+003 L/kg wet-wt based on the BCFBAF v3.00 model. However, these estimates are not likely to be valid as they do not consider hydrolysis or biotransformation of DiTDP, both of which are expected to be great. The BCF value of the primary hydrolysis product, isotridecanol, is <100 L/kg based on test data.