Disodium dihydrogenpyrophosphate

Particle size distribution (Granulometry)

Link to relevant study record(s)

Reference

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Qualifier:

no guideline followed

Principles of method if other than guideline:

The samples were drawn through a Sierra 218 cascade impactor at 2.78 liters per minute. The aerodynamic particle size distribution was determined by gravimetric analysis of the amount of test material collected on the impactor stages and subsequent determination of the mass median aerodynamic diameter (MMAD), geometric standard deviation and other particle size parameters by logarithmic-probability plotting.

GLP compliance:

yes

Type of method:

cascade impaction

Type of distribution:

counted distribution

Percentile:

D50

Mean:

> 4.61 - < 4.87 µm

Remarks on result:

other: with geometric standard deviations ranging from 2.98 to 3.39(migrated from fields under 'Mass median diameter' as D50 percentile. No source field for Standard deviation.)

The MMAD represents the smallest size that could be achieved in this study. The material is hygroscopic causing the particles to agglomerate and/or adhere to surfaces inside the chamber. Several trials were initially performed with various generation schemes and the system which was ultimately chosen provided the best performance.

 

- Particle size distribution: The fraction of particles less than or equal to 1 µm in mass aerodynamic diameter, based on the log-probability graphs, ranged from 7.6 to 9.4%. The fraction of particles less than or equal to 10 µm in mass aerodynamic diameter, based on the log probability graphs, ranged from 72.3 to 76.1%. These results indicated the test material was respirable in size to the rat.

Conclusions:

The MMAD represents the smallest size that could be achieved in this study. The material is hygroscopic causing the particles to agglomerate and/or adhere to surfaces inside the chamber.
The substance tested is considered to pose an inhalation risk and be respirable in size to the rat. This study is conducted according to the appropriate method and under the conditions of GLP and therefore the study is considered to be acceptable and to adequately satisfy both the guideline requirement and the regulatory requirement as a key study for this endpoint.         

Description of key information

The data concludes that disodium dihydrogenpyrophosphate presents an inhalation risk. 

Additional information

The MMAD (>4.61 < 4.87 µm) represents the smallest size that could be achieved in this study. The material is hygroscopic causing the particles to agglomerate and/or adhere to surfaces inside the chamber.

Particle size distribution: The fraction of particles less than or equal to 1 µm in mass aerodynamic diameter, based on the log-probability graphs, ranged from 7.6 to 9.4%. The fraction of particles less than or equal to 10 µm in mass aerodynamic diameter, based on the log probability graphs, ranged from 72.3 to 76.1%. These results indicated the test material was respirable in size to the rat.

In addition, data provided by registrants supports the assertion that disodium dihydrogenpyrophosphate is inhalable (>90% of particles were <100 µm)