Trisodium 1-(1-naphthylazo)-2-hydroxynaphthalene-4',6,8-trisulphonate

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because exposure of humans via inhalation is not likely taking into account the vapour pressure of the substance and/or the possibility of exposure to aerosols, particles or droplets of an inhalable size

Justification for type of information:

The substance has a negligible vapour pressure, thus being unlikely available for inhalation as a vapour. Based on particle size distribution, 100 % in volume of particles have diameter below 100 µm.
In general, particles of 10-100 µm size are inhalable, particles of 4-10 µm size are thoracic and of 0-4 µm are respirable. Inhalable and thoracic fractions remain in the high respiratory tract and may be cleared from this region by mucous, cough...; part of these particles become available by oral route upon swallowing. Respirable fraction may enter the deepest part of lungs, namely the non-ciliated alveoli and become systemically available upon absorption.
As for test substance, less than 14 % in volume of particles has diameter below 4 µm. In addition, test substance has a low logPow value, thus indicating a low potential for crossing biological membranes. On these bases, absorption via inhalation route possibly resulting in acute toxicity was considered as not likely to occur and inhalation route was considered not relevant for human exposure.