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Physical & Chemical properties

Vapour pressure

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vapour pressure
Type of information:
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
See attached QMRF/QPRF
Principles of method if other than guideline:
The result was obtained using a valid read across from its parent acid.
Key result
Test no.:
25 °C
Vapour pressure:
< 0 hPa

< 1.7 x 10E-8 Pa

A vapour pressure value of <1.7E-08 Pa at 25°C was obtained using an accepted calculation method. The result is considered to be reliable.

Description of key information

Vapour pressure [HEDP (2-3Na)]: < 1.7E-08 Pa at 25°C (QSAR)

Key value for chemical safety assessment

Vapour pressure:
0 Pa
at the temperature of:
25 °C

Additional information

The vapour pressure of the sodium salt of HEDP has been read-across from the parent acid (HEDP-H). A predicted vapour pressure of 1.7E-8 Pa at 25°C was obtained for HEDP-H using an accepted calculation method (MPBPVP program, USEPA/Syracuse Research, v1.43). This predicted value is read-across to the salt, HEDP (2-3Na) as <1.7E-8 at 25°C since the vapour pressure of the salt is expected to be lower than that of the parent acid. The result (Fisk 2010) is considered to be reliable and is selected as a key study.


The minor constituents are phosphonate salts that are structurally similar to the main constituent or inorganic salts; all will have negligible vapour pressure.