Tierexperimentelle Untersuchungen zeigen für einige Kohlenstoffnanofasern eine kanzerogene Wirkung. Gleichzeitig wird die nanoskalige faserförmige Fraktion in den in Deutschland geltenden Regelwerken zur Bestimmung der Konzentration faserförmiger anorganischer Partikel bisher nicht berücksichtigt. Für die Überprüfung luftgetragener Anzahlkonzentrationen nano- und mikroskaliger Fasern am Arbeitsplatz wurde deshalb ein neues Mess- und Analyseverfahren entwickelt, das Fasern mit einem Durchmesser ab 20 nm mit einbezieht. Dieses neue Messverfahren wurde nun an realen Arbeitsplätzen angewandt und die Durchführbarkeit und Praktikabilität bewertet. Die durchgeführten Arbeitsplatzmessungen werden im Folgenden vorgestellt und identifizierte Probleme bei der Anwendung des Verfahrens sowie Lösungsvorschläge erläutert. Für verschiedene Tätigkeiten mit faserförmigen Nanomaterialien konnten mit dem neuen Messverfahren Faserfreisetzungen detektiert und die praktische Umsetzung für eine Nachweisgrenze von 10 000 F(20 nm)/m³ gezeigt werden.

Animal experiments show a carcinogenic effect for some carbon nanofibres. At the same time the nanoscale fibrous fraction has not yet been taken into account in the German regulations for determining concentrations of fibrous inorganic particles. For the assessment of airborne number concentrations of nano- and microscale fibres at the workplace a new measurement and analysis method was developed which includes fibres with a diameter of 20 nm and more. This new measurement method has now been applied to real workplaces and its feasibility and practicability evaluated.The workplace measurements performed are presented in the following and identified problems in application of the method as well as proposed solutions are explained. Fibre releases could be detected using the new measurement method for different activities with fibrous nanomaterials and the practical implementation for a detection limit of 10,000 F(20 nm)/m(3) could be demonstrated.

A methodology is presented to investigate safety aspects of processes for the manufacturing and machining of metallic fiber-reinforced composites. The aim is to establish application-safe processes by identifying risks of releasing potentially hazardous dusts at an early stage and by selecting suited protective measures. In the application investigated here, composites made of copper (Cu) with carbon nanotubes (CNT) or carbon nanofibers (CNF) are produced and processed. As electrical conductors and as thermally conductive contact materials, they benefit from the properties of the added carbon materials. On the one hand, tangled carbon nanotubes with diameters of approx. 20 nm and rigid CNFs with diameters of approx. 100 nm were used. For both types of fibers, the dust release propensity of the dry powder was first determined in the laboratory by morphologically characterizing, classifying and quantifying the dust produced in a vibrofluidization process. To assess the fiber exposure of employees, the airborne fiber number concentrations were then measured at the workplaces for producing and machining both composite materials. A new measurement protocol for aerosols containing nanoscale fibers was applied, which is currently being validated in a project funded by the German Social Accident Insurance (DGUV).

Es wird eine Methode vorgestellt, um Sicherheitsaspekte von Prozessen zu untersuchen, mit denen metallische faserverstärkte Verbundwerkstoffe hergestellt und bearbeitet werden. Ziel ist, zu anwendungssicheren Prozessen zu gelangen, indem Gefahren gesundheitsgefährdender Stäube möglichst frühzeitig identifiziert und geeignete Schutzmaßnahmen ausgewählt werden. In der hier untersuchten Anwendung wurden Komposite aus Kupfer (Cu) mit Kohlenstoffnanoröhren (carbon nanotubes, CNTs) oder Kohlenstoffnanofasern (carbon nanofibers, CNFs) hergestellt und bearbeitet. Sie profitieren als elektrische Leiter und thermisch leitfähige Kontaktmaterialien von den Eigenschaften der zugesetzten Kohlenstoffmaterialien. Es kamen zum einen verknäulte CNTs mit Durchmessern von ca. 20 nm zum Einsatz, zum anderen rigide CNFs mit Durchmessern von ca. 100 nm. Für beide Fasertypen wurde zunächst im Labor die Staubungsneigung des trockenen Pulvers bestimmt, indem der Staub, der in einem Vibro-Fluidisierungsprozess entsteht, morphologisch charakterisiert, klassifiziert und quantifiziert wurde. Zur Bestimmung der Faserexposition von Beschäftigten erfolgte im Anschluss die Messung der luftgetragenen Faseranzahlkonzentrationen an den Arbeitsplätzen. Dabei kam ein neues Messverfahren für Aerosole aus nanoskaligen Fasern zur Anwendung, das derzeit durch ein Projekt der Deutschen Gesetzlichen Unfallversicherung e. V. (DGUV) validiert wird.

The second questionnaire campaign conducted by the German Federal Institute for Occupational Safety and Health (BAuA) on the handling and production of nanomaterials in Germany accommodates the increasing importance of the nanotechnology branch. The aim was to update the first questionnaire campaign on focus point in nanotechnology and to deepen several issues from that campaign in order to be able to derive a need of action when recommending possible safety measures. The survey gives an overview of the different industry branches that produce, process and release nanomaterials. Statements are given on the amount and kind of produced and processed nanomaterials in Germany and to the safety measures applied while handling these substances. Industry mainly produces and uses the traditional materials listed on the OECD list of manufactured nanomaterials. Multi walled carbon nanotubes (MWCNT) are the most important materials for research institutions. The exposure measurements showed short-time peak concentrations in particle number concentration above the background. Future exposition measurements shall focus their causes and sources. First findings on experience and application of occupational hygiene management systems for the handling of nanomaterials in work sites were gathered and evaluated.

Measurements of the inhalative exposure to nanomaterials at the workplace require not only expert knowlegde about the application of sophisticated equipment but also an investigative approach for the detection of probable background contaminants for representative measurement results. To harmonize the measurement procedure, conventions for the detection of ultrafine aerosols/nanomaterials were taken up. A tiered approach for the measurement and assessment of nanomaterial exposure was compiled, implementing special standard operation procedures (SOPs). This paper summarizes the validation phase of the SOPs. On the one hand the measurement devices used were tested for applicability. On the other hand the approach by different institutes to the measurement strategy was compared. Based on the impressions and experience attained by applying the tiered approach different exposure assessments are discussed critically. An outlook to possible harmonized measurements of exposure is also given. Especially the determination of exposure to fibrous nanomaterials is discussed since a morphological and therefore effect based characterization of diverse carbon nanotubes (CNTs) and carbon nanofibers (CNFs) seems to be mandatory.