Registration Dossier

Physical & Chemical properties

Particle size distribution (Granulometry)

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Amorphous Boron Powder Grade I has a median diameter of 1.78 µm. This is the boron powder on the market with the smallest size. At the same time, this grade also has the highest market share in terms of tonnage.

Note that approx. 96% of the registered tonnage of boron is placed on the EU market in the form of alloys, and only ca. 4 % in the form of pure boron. Detailed, but confidential information on particle size grades of boron and their tonnages has been submitted to ECHA on 27 June 2017, in a response to communication CCH-D-2114358633-45-01/D. The tonnage information is not repeated here for confidentiality reasons, but some data on other boron powder size grades is included in individual endpoint study records in the technical dossier.

Amorphous Boron Powder Grade I shows a high dustiness (45 and 34%) with a high MMAD (122 and 92 μm). According to the MPPD-model, only about 1.2 % or less of inhaled material are predicted to deposit in the pulmonary region. Therefore, inhalation is not a relevant route of exposure for boron. See also "Attached Justification" for data waiving for repeated dose toxicity studies (technical dossier IUCLID sections 7.5.2).

For details on the calculations of MMADs and fractional deposition in the respiratory tract with the MPPD-Model, please refer to the endpoint study records titled "k_Parr, Grewe...". These include details on the calculations, including MPPD model parameters, in particular in the fields "any additional information on methods" and "... results".

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