[Trends of activities in international organization and authorities in each country regarding risk management of nanomaterials].

The Organisation for Economic Co-operation and Development (OECD) estimates that in 2015 the worldwide nanotechnology-related market will reach about US$1 trillion and will create about two million additional jobs. The field began with the general technical industry, including many areas of the pharmaceutical, medical, agricultural, and environmental/energy industries, and recently has expanded to the formulation of nanotechnology. In particular, elements of nanometer-sized research and development (R & D) in the areas of drug delivery systems and nanomedicine are attracting widespread interest. On the other hand, the potential negative effects on human health and the environment of nanomaterials manufactured on the industrial scale have not been investigated in detail. Therefore, although the risks have not been fully clarified, research institutions and international organizations such as the OECD are working in earnest to elucidate them. This paper outlines the status of initiatives in industry and regulatory conditions and trends in individual countries and institutions to determine the safety of nanomaterials from the perspective of international relations.

Blood concentrations of acrylonitrile in humans after oral administration extrapolated from in vivo rat pharmacokinetics, in vitro human metabolism, and physiologically based pharmacokinetic modeling.

The present study defined a simplified physiologically based pharmacokinetic (PBPK) model for acrylonitrile in humans based on in vitro metabolic parameters determined using relevant liver microsomes, coefficients derived in silico, physiological parameters derived from the literature, and a prior previously developed PBPK model in rats. The model basically consists of a chemical absorption compartment, a metabolizing compartment, and a central compartment for acrylonitrile. Evaluation of a previous rat model was performed by comparisons with experimental pharmacokinetic values from blood and urine obtained from rats in vivo after oral treatment with acrylonitrile (30 mg/kg, a no-observed-adverse-effect level) for 14 days. Elimination rates of acrylonitrile in vitro were established using data from rat liver microsomes and from pooled human liver microsomes. Acrylonitrile was expected to be absorbed and cleared rapidly from the body in silico, as was the case for rats confirmed experimentally in vivo with repeated low-dose treatments. These results indicate that the simplified PBPK model for acrylonitrile is useful for a forward dosimetry approach in humans. This model may also be useful for simulating blood concentrations of other related compounds resulting from exposure to low chemical doses.