Reaction mass of 1,1,1,5,5,5-hexamethyl-3-phenyl-3-((trimethylsilyl)oxy)trisiloxane and 1,1,1,7,7,7-hexamethyl-3,5-diphenyl-3,5-bis[(trimethylsilyl)oxy]tetrasiloxane and 1,1,1,9,9,9-hexamethyl-3,5,7-triphenyl-3,5,7-tris((trimethylsilyl)oxy)pentasiloxane

Endpoint summary

Additional information

The distribution in a sewage treatment plant (STP) has been estimated using the SimpleTreat model (implemented in EUSES 2.1.2), see table below.

Table: Distribution modelling for STP

Fraction of emission directed to air by STP	6.04	[%]
Fraction of emission directed to water by STP	7.09	[%]
Fraction of emission directed to sludge by STP	86.9	[%]
Fraction of the emission degraded in STP	0	[%]

The constituents of phenyl silsesquioxanes are not expected to undergo any significant biodegradation, and are predicted to have high Henry’s Law constants and high log K_ow/log K_oc. Distribution modelling for STP indicates that sludge is the main compartment to which they are expected to partition in a sewage treatment plant, with partition to water and air also being significant. Sediment and soil are likely to be the main compartments to which phenyl silsesquioxanes will partition in the wider environment.