Cross-sectional risk assessment of various nano materials and production stages

To better estimate the potential risk of nano materials, correspondence relationships were investigated between material properties and many kinds of biomarkers indicating adverse effects on humans. Nano materials have a variety of properties such as solubility, iso-electric point, crystal shape (coordination number), BET specific surface area and so on for each material. To the best of the authors' knowledge, no research has yet been carried out to determine which kinds of material properties have effects on biomarkers indicating adverse effects on humans. The purpose of our work was to predict a relationship between material properties and hazard data by undertaking a bibliographical survey. Various keyword searches related to nano risk were performed on the internet. Keywords on health effects were included in the searches to check for any possible risks of environmental emissions. Biomarker values were carefully selected from a large number of tables and figures appearing in various articles. However, except for data on size, such as for diameter and aspect ratio, toxicological reports contained a scarcity of data on nano materials compared with data for biomarkers. Additional data on nano materials were found by searching nano material handbooks and manufacturers' catalogs. Results of our investigation were as follows. With respect to cytotoxicity, it probably depends mainly on the particle volume dose and to a certain degree on particle solubility. It can be concluded from these results that there is a relationship between material properties and hazard data. Many activities involving nano risk are occurring all over the world. However, a major obstacle to the identification of specific risks is that at present nano materials are often very broadly categorized and named based upon their basic material composition or product shape - e.g., “titanium,” “carbon black,” “nano tubes,” etc. Such rough, imprecise categorization serves little or no useful purpose when attempting risk assessments for particular types of nano materials since materials with the same name can possess differing particle-level properties indicating differing degrees of hazard.