Lynn Bergeson’s June 21, 2016 posting on Nanotechnology Now announced a newly published guidance document from the European Union’s nanoIndEx,
… The guidance document summarizes the key findings of the project, and is intended to present the state of the art in personal exposure assessment for nanomaterials. The conclusions section states: “Unfortunately, many nanotoxicological studies have used excessive, unrealistically high doses of [manufactured nanomaterials] and it is therefore debatable what their findings mean for the lower real-world exposures of humans. Moreover, it is not clear how to establish realistic exposure dose testing in toxicological studies, as available data on occupational exposure levels are still sparse.” According to the guidance document, future studies should focus on the potentially adverse effects of low-level and realistic exposure to manufactured nanomaterials, especially through the use of exposure doses similar to those identified in environmental sampling.
… While human exposure to MNMs may in principle occur during any stage of the material’s lifecycle, it is most likely in workplaces, where these materials are produced or handled in large quantities or over long periods of time. Inhalation is considered as the most critical uptake route, because the small particles are able to penetrate deep into the lung and deposit in the gas exchange region. Inhalation exposure to airborne nanomaterials therefore needs to be assessed in view of worker protection.
Exposure to airborne particles can generally best be assessed by measuring the individual exposure in the personal breathing zone (PBZ) of an individual. The PBZ is defined as a 30 cm hemisphere around mouth and nose . Measurements in the PBZ require instruments that are small and light-weight. The individual exposure specifically to MNMs [manufactured nanomaterials, sometimes also known as engineered nanomaterials or nanoparticles] has not been assessable in the past due to the lack of suitable personal samplers and/or monitors. Instead, most studies related to exposure to MNMs have been carried out using either bulky static measurement equipment or not nanospecific personal samplers. In recent years, novel samplers and monitors have been introduced that allow for an assessment of the more nanospecific personal exposure to airborne MNMs. In the terminology used in nanoIndEx, samplers are devices that collect particles on a substrate, e.g. a filter
of flat surface, for subsequent analysis, whereas monitors are real-time instruments that deliver
information on the airborne concentrations with high time resolution. Scientifically sound investigations on the accuracy, comparability and field applicability of these novel samplers and monitors had been lacking. … (p. 4 print; p. 6 PDF)
There’s also a brief description of the nanoindEX project in the Introduction,
The three-year project started on June 1st, 2013, and has been funded under the frame of SIINN, the ERA-NET [European Research Area Network] for a Safe Implementation of Innovative Nanoscience and Nanotechnology [SINN]. The aim of the project was to scrutinise the instrumentation available for personal exposure assessment concerning their field readiness and usability in order to use this information to generate reliable data on personal exposure in real workplaces and to eventually widely distribute the findings among the interested public. This Guidance Document you are holding in your hands summarises the key findings of the project. (p. 5 print; p. 7 PDF)
As I understand it, the area of most concern where nanotoxicology is concerned would be inhalation of nanoparticles into the lungs as the body has fewer protections in the respiratory tract than it has elsewhere, e.g. skin or digestive system.