[No public or meaningful name is available]

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

other: Assessment based on available information for constituents

Adequacy of study:

weight of evidence

Study period:

2022

Reliability:

other: Assessment

Rationale for reliability incl. deficiencies:

other: Assessment based on the available information for the constituents.

Data source

Reference

Reference Type:

other: Assessment report

Title:

Unnamed

Year:

2022

Report date:

2022

Materials and methods

Principles of method if other than guideline:

An assessment of acute inhalation endpoint of the registered substance was performed based on the information available on the constituents (see attachment for full details).

Test type:

other: Assessment based on the information available for the constituents.

Test material

Test material information

Constituent 1

Reference substance name:

Unknown

Cas Number:

Unknown

IUPAC Name:

Unknown

Constituent 2

Reference substance name:

Calcium oxide

EC Number:

215-138-9

EC Name:

Calcium oxide

Cas Number:

1305-78-8

Molecular formula:

CaO

IUPAC Name:

oxocalcium

Constituent 3

Reference substance name:

Quartz (SiO2)

EC Number:

238-878-4

EC Name:

Quartz (SiO2)

Cas Number:

14808-60-7

Molecular formula:

SiO2

IUPAC Name:

Quartz

Constituent 4

Reference substance name:

Zinc sulphide

EC Number:

215-251-3

EC Name:

Zinc sulphide

Cas Number:

1314-98-3

Molecular formula:

SZn

IUPAC Name:

thioxozinc

Constituent 5

Reference substance name:

Silicon dioxide

EC Number:

231-545-4

EC Name:

Silicon dioxide

Cas Number:

7631-86-9

Molecular formula:

O2Si

IUPAC Name:

Silicon dioxide

Constituent 6

Reference substance name:

Carbon

EC Number:

231-153-3

EC Name:

Carbon

Cas Number:

7440-44-0

Molecular formula:

C

IUPAC Name:

Carbon

Test material form:

solid: nanoform

Remarks:

Fine black powder

Details on test material:

- State of aggregation:
spherical particles clustered together to form loose aggregates in organic media.

- Particle size distribution:
median (d(50)) size of 27.51 nm at the major axis and 23.62 nm at the minor axis.

- Shape of particles:
Spheroid

- Surface area of particles:
136.368 m2 cm-3

- Coating:
none

Results and discussion

Effect levels

Key result

Remarks on result:

other: It is not possible to quantitatively derive the registered substance’s LC50. However, based on the available data on the constituents, acute hazard from the relevant constituents is not expected and the CLP classification criteria not met.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Due to the lack of defined LC50 values for the majority of the constituents (LC50 higher than the tested doses), it is not possible to quantitatively derive the registered substance’s LC50. However, based on the available data on the constituents, acute hazard from the relevant constituents is not expected and the registered substance does not meet the criteria for the classification as per the CLP regulation (See attachment for full assessment).

Executive summary:

A constituent-based approach for the read across was applied for the substance.

 

Toxicity data available for the known constituents (except quartz) showed that these constituents did not cause lethality in test animals up to the highest inhalation concentrations tested; however, data on several main constituents come from studies where highest concentrations used were far below the limit concentrations typically suggested by regulatory guidelines; therefore, hazard at higher doses cannot be ruled out. Nonetheless, it is noteworthy that these major constituents in the test substance usually exist in in the powder forms and at the highest testing concentrations which are recommended by regulatory acute inhalation studies (up to 5 mg/L), dry powder aerosols of poorly soluble substances tend to form conglomerates causing physical obstruction of the animals’ airways and impaired respiration and suffocation. Death caused via this mode of action should not be misdiagnosed as toxic effect (see also OECD Guidance #39 on Inhalation Toxicity Studies 2018, section 69). This appears to be the reason why the data available in the literature for these constituents is usually at low concentrations. 

 

For quartz, no acute inhalation toxicity data is available. Silicosis is one of the oldest known occupational diseases. It has only been observed following occupational exposure to respirable crystalline silica and not through exposure to crystalline silica in ambient air. Long term exposure to silica is more relevant because it is potentially carcinogenic and causes progressive, irreversible, fibrotic lung disease. Although acute hazard of quartz is not known, at low concentrations available in the registered substance (~1%), acute toxicity of quartz appears to be even less relevant. For example: low-level crystalline silica exposure on beaches and in ambient air in general, there is no evidence that such low-level exposure causes health effects.

 

Among the unknown constituents (~6%), no one component is present at >1% w/w; hence, they are not relevant for the acute toxicity hazard classification as per the CLP regulation. 

 

In conclusion, due to the lack of defined LC50 values for the majority of the constituents (LC50 higher than the tested doses), it is not possible to quantitatively derive the registered substance’s LC50; however, based on the available data on the constituents, acute hazard from the relevant constituents is not expected and the registered substance does not meet the criteria for the classification as per the CLP regulation.