1,3,4-thiadiazole-2,5-dithiol

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

Study period:

2017-10-16 - 2017-05-18

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions) - Method B: Fibre Length and Diameter Distributions

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

other: fractionated by a 100 µm sieve and tested by scanning electron microscopy (SEM).

Type of particle tested:

primary particle

Type of distribution:

mass based distribution

Specific details on test material used for the study:

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing:
The sample was fractionated by 100 µm sieve and tested by scanning electron microscopy. The fraction < 100 µm was gushed to carbon pads and sputtered with gold.

Mass median aerodynamic diameter:

19.7 µm

Remarks on result:

other: Mass Median Aerodynamic Diameter of the fraction < 100µm, which is 5.17% of the test item (sieve mass fraction <100µm)

Key result

Percentile:

other: 5.17%

Mean:

< 100 µm

Remarks on result:

other: sieve mass fraction

Key result

Percentile:

other: 5.14%

Mean:

>= 10 - <= 100 µm

Remarks on result:

other: sieve mass fraction

Remarks:

inhalable fraction

Key result

Percentile:

other: 0.03%

Mean:

>= 4 - <= 10 µm

Remarks on result:

other: sieve mass fraction

Remarks:

thoracic fraction

Key result

Percentile:

other: 0.00%

Mean:

<= 4 µm

Remarks on result:

other: sieve mass fraction

Remarks:

respirable fraction

Conclusions:

The study was performed according to OECD 110 (method B) under GLP on the substance to be registered itself, the test procedure is well documented and therefore reliability of Klimisch 1 has been assigned. First, the sample was fractionated by a 100 µm sieve, resulting in a sieve mass fraction <100 µm of 5.17%, clearly indicating that the substance has a very low potential to be inhaled. This small portion was further examined by scanning electron microscopy, revealing the following distribution, fraction according their biological relevance (spherical volume): 5.14% 10-100 µm (inhalable), 0.03% 4-10 µm (thoracic), and 0.00% <4 µm (respirable), clearly showing that, if the substance is inhaled at all, it will be practically in total retained in the upper respiratory tract, where it is subject to ciliary cleaning mechanisms.

Executive summary:

The particle size distribution of 2,5-Dimercapto-1,3,4-thiadiazole (DMTD) was determined by scanning electron microscopy after the sample was fractionated by a 100 µm sieve in an OECD 110 (method B) guideline study under GLP. The results are:

 

Sieve Fraction:

weighted sample: 0.996 g

weight fraction <100 µm: 0.0515 g

Sieve mass fraction <100 µm: 5.17%

 

Mass Fraction

Sieve Fraction nominal < 100 µm

Particle Size	Spherical Volume	Cubical Volume
< 4 µm (respirable)	0.00 %	0.00 %
4-10 µm (thoracic)	0.65 %	0.96 %
10-100 µm (inhalable)	99.35 %	99.04 %
>100 µm	0.00 %	0.00 %
Median (diameter)	19.70 µm	19.08 µm

 

The MMAD (Mass Median Aerodynamic Diameter < 100 µm) has a value of 19.70 µm as spherical particles.

Accounting based on the total sample weight
	Particle Size [µm]	Spherical Volume [%]
Mass Fraction	> 100	94.83
Sieve Fraction	> 100	0.00
Total (> 100 µm)		94.83
Sieve Fraction	10-100 (inhalable)	5.14
Sieve Fraction	4-10 (thoracic)	0.03
Sieve Fraction	< 4 (respirable)	0.00

Description of key information

Particle size distribution (sieve fractioned, SEM, OECD 110, method B, GLP): sieve mass fraction < 100 µm: 5.17%, MMAD (<100µm) = 19.70 µm, 5.14% 10-100 µm (inhalable), 0.03% µm 4-10 (thoracic), and 0.00% <4 µm (respirable)