The large use of nanomaterials in several industrial processes drove the attention toward the potential health issues associated to their diffusion in the environment. However, since nanomaterials are characterized by a polidisperse particle size distribution, the human health risk induced by a nanoparticle (NP) contamination cannot be assessed through the ASTM procedure commonly used for chemicals. Toxicity and environmental mobility of NP are in fact typically strongly influenced by their size. In this study, a general approach to adapt the ASTM procedure to NP contaminated aquifers is proposed. The analytical solutions used for Tier 2 risk analysis of dissolved compounds have been adapted and extended to account for NP transport mechanisms. Two applications of the proposed procedure, one theoretical and one based on experimental-modelling results, are presented, highlighting the role of particle size heterogeneity on the assessment of human health risk.

The large use of nanomaterials in several industrial processes drove the attention toward the potential health issues associated to their diffusion in the environment. However, since nanomaterials are characterized by a polidisperse particle size distribution, the human health risk induced by a nanoparticle (NP) contamination cannot be assessed through the ASTM procedure commonly used for chemicals. Toxicity and environmental mobility of NP are in fact typically strongly influenced by their size. In this study, a general approach to adapt the ASTM procedure to NP contaminated aquifers is proposed. The analytical solutions used for Tier 2 risk analysis of dissolved compounds have been adapted and extended to account for NP transport mechanisms. Two applications of the proposed procedure, one theoretical and one based on experimental-modelling results, are presented, highlighting the role of particle size heterogeneity on the assessment of human health risk.