English to Russian Science Chemistry; Chem Sci/Eng

Помогите, пожалуйста, перевести фразу expressed as a function of surface area (выдержка из документа OECD guidance on sample preparation and dosimetry for the safety testing of manufactured nanomaterials):

Dosimetry should always report mass concentration, but for nanomaterials, the results may be better expressed as a function of surface area or particle number because particle size and specific area may play a major role in determining the toxicity of nanomaterials