In FY14, recruitment efforts continued to identify and enroll companies producing or using CNTs or CNFs. A total of eight exposure assessment site visits were conducted while only six were eligible to participate as part of the epidemiologic survey which included the sputum collection procedures. Exposure assessment sampling was conducted at 4 primary producers and 4 downstream users of CNTs and CNFs. Out of the four primary manufacturers visited, two produced multi-walled CNT in varying lengths and diameters while one company each produced single-walled CNT and CNF. Two of the four primary producers were small companies (3 to 15 employees) while the other two were medium sized companies (35-60 employees). Two of the four downstream user companies visited focused on the use of aqueous single-walled CNT solutions for applications in the electronics industry. The other two companies used large quantities of multi-walled CNT with applications in the aerospace industry for advanced composite materials. One of these companies primarily received their multi-walled CNT in aqueous solution, reducing the exposure potential, while the other received the material in powder form. One of the four downstream users was considered a small company (3 to 15 employees) while another was a medium sized company (35-50 employees). The remaining two downstream users were larger companies with >500 employees site wide. Respirable and inhalable air samples were collected for chemical analyses (NMAM 5040 for elemental carbon [EC] and transmission electron microscopy). 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 on the hand and wrists of workers. 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.
