In FY13, recruitment efforts continued to identify and enroll companies producing or using CNTs or CNFs. A total of six exposure assessment and epidemiologic surveys, including sputum collection procedures, were conducted at 3 primary producers and 3 downstream users of CNTs and CNFs. These included three small to medium scale downstream users. All three downstream companies focused on the creation of resin/CNT, specifically MWCNT, formulations for the creation of advanced composite materials for military and industrial uses. The three primary manufacturers visited produced multi-walled CNT in varying lengths and diameters while one of the three companies involved in primary production focused mainly on the production of single-walled CNT. Respirable and inhalable air samples were collected for chemical analyses. Based on the preliminary EC results, exposures at the respirable size fraction were found, among some workers, to be above the finalized NIOSH REL of 1 ?g/m3 and the presence of airborne CNTs was confirmed by electron microscopy. However, a great majority of the EC samples were well below the respirable NIOSH REL. Bulk samples of the materials, when provided, were collected and will be used to measure concentrations of polycyclic aromatic hydrocarbons and residual metals. All samples have been submitted for analysis and company reports are currently being drafted. Dermal samples were collected from the hands and wrists of workers enrolled in the study. These samples were analyzed by scanning electron microscopy. In addition, induced sputum was collected from participating workers who met certain health criteria. These specimens are being analyzed by enhanced dark field microscopy, which will provide visual evidence of exposure to CNTs within the airways and lower regions of the lung.
